Evaluation of the Wastewater Quality Improvement by The Channel Located Downs...
PhaseIIIAldergroveRegionalParkRestoration
1. Phase III Restoration of Aldergrove Regional Park
Project Team:
Emma de Groot
Elise Mackie
Masheed Salehomoum
Project Supervisor: Eric Anderson
Applied Research Projects (RENR 8303)
22 April 2016
A REPORT SUBMITTED IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE BACHELOR OF SCIENCE
IN
ECOLOGICAL RESTORATION
BRITISH COLUMBIA INSTITUTE OF TECHNOLOGY
2. ii
PHASE III RESTORATION OF ALDERGROVE REGIONAL PARK
By:
ELISE MACKIE
EMMA DE GROOT
MASHEED SALEHOMOUM
A REPORT SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
BACHELOR OF SCIENCE
In
ECOLOGICAL RESTORATION
RENEWABLE RESOURCES TECHNOLOGY
SCHOOL OF CONSTRUCTION AND THE ENVIRONMENT
We accept this report as conforming to the required standard
____________________
SUPERVISOR
____________________
PROGRAM HEAD
BRITISH COLUMBIA INSTITUTE OF TECHNOLOGY
April 2016
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EXECUTIVE SUMMARY
Wetlands are critical ecosystems for water purification, habitat, flood mitigation, food
production, and nutrient cycling. Due to the high soil fertility of wetlands, many were
converted into agricultural land resulting in a 70% loss of this ecosystem type in the Lower
Fraser Valley. This report is a proposed restoration plan for Phase III of a multiphase
restoration project in the southern lowlands of Aldergrove Regional Park in Langley, BC.
Phase III is an extension of a larger complex of restoration projects already underway in
the southern lowlands of the park.
The restoration of the Phase III site will consist of two main treatments (1) the creation of
an ephemeral swamp and (2) the enhancement of an agricultural pond. To construct the
ephemeral swamp, we will exaggerate existing microtopography on the site. We will create
wetted depressions surrounded by dry, elevated areas dominated by woody vegetation.
This expanded wetland complex will satisfy the goal of expanding suitable habitat for
native amphibian species in Aldergrove regional park, with special attention to the Oregon
Spotted Frog, the Red Legged Frog and the Western Toad. To enhance the agricultural pond
we will add compost amendments, increase microtopography and plant emergent
vegetation to mitigate low dissolved oxygen in the pond. To enhance the ponds suitability
for fish habitat we will regrade the steep banks making it more suitable for emergent
vegetation establishment while also expanding the wetted area. This treatment will satisfy
the goal of expanding suitable habitat for native fish species in Aldergrove Regional Park,
with special attention to the Salish Sucker, Cutthroat Trout and juvenile Coho Salmon.
Additional restoration treatments for the Phase III site include invasive removal, native
plantings, slope stabilization and the creation of a pollination garden.
The two main restoration treatments were formulated after we conducted baseline
monitoring of the site. We conducted vegetation, and water quality surveys in the fall and
winter of 2015/16). Hydrology monitoring will occur over the summer of 2016 prior
implementing treatments. We have provided methods for monitoring and maintenance of
the Phase III site to assess the success of the Phase III Restoration in Aldergrove Regional
Park.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY.....................................................................................................................................III
LIST OF FIGURES..............................................................................................................................................VIII
LIST OF TABLES................................................................................................................................................... IX
ACKNOWLEDGEMENTS .....................................................................................................................................X
1. INTRODUCTION............................................................................................................................................1
2. SITE HISTORY................................................................................................................................................4
2.1. Glaciation.....................................................................................................................................................4
2.2. Historical Human Presence..................................................................................................................4
2.3. Historical Ranges of At-risk Species.................................................................................................4
2.4. Park History ...............................................................................................................................................6
2.5. Park Restoration History ......................................................................................................................6
2.6. Phase III Site History ..............................................................................................................................7
3. CURRENT PHASE III SITE CONDITIONS..............................................................................................9
3.1. Land Use and Infrastructure................................................................................................................9
3.2. Climate ...................................................................................................................................................... 10
3.3 Topography.............................................................................................................................................. 11
3.4. Soils ............................................................................................................................................................ 11
3.5. Hydrology................................................................................................................................................. 11
3.6. Water Quality.......................................................................................................................................... 12
3.7. Vegetation................................................................................................................................................ 13
3.8. Fish and Wildlife.................................................................................................................................... 15
4. STRESSORS.................................................................................................................................................. 15
4.1 Agriculture and Hydrological Alterations .................................................................................... 15
4.2. Invasive Species..................................................................................................................................... 17
8. viii
LIST OF FIGURES
Figure 1. The southern lowland portion of Aldergrove Regional Park with key ecological
restoration and agricultural activities, in Aldergrove, BC.....................................................................2
Figure 2. Historical photos depicting the agricultural uses in the Phase III restoration site in
Aldergrove Regional Park, BC. .........................................................................................................................8
Figure 3. Map depicting current and previous site attributes including infrastructure,
topography, soil pit locations, and hydrological features, of the Phase III site located in
Aldergrove Regional Park, BC....................................................................................................................... 10
Figure 4. Dominant vegetation on Phase III Restoration Site in Aldergrove Regional Park,
BC based on aerial photos and field surveys conducted on 19 and 26 November 2015....... 14
Figure 5. Map of proposed restoration treatments and their locations. ...................................... 25
Figure 6. Schematic of the pond expansion and regrading treatment to be implemented on
the Phase III Restoration Site, at Aldergrove Regional Park BC.. .................................................... 36
Figure 7. Visualization of grade control structure that will be installed at the lower end of
the expanded pond on the Phase III site................................................................................................... 39
Figure 8. Planting zones for restoration plan.......................................................................................... 45
Figure 9. An example of a wattle fence that will be installed on the steepest part of the
northern slope situated on the Phase III Site in Aldergrove Regional Park, BC........................ 48
Figure 10. Schematic of modified brush layers that will be installed on the steepest part of
the northern slope situated on the Phase III site in Aldergrove Regional Park, BC................. 49
Figure 11. A summary of water quality data collected in the existing pond at the Phase III
Restoration Site in Aldergrove Regional Park, BC................................................................................. 54
Figure 12. Schematic of sampling design for vegetation surveys in the Aldergrove Regional
Park Phase III Restoration Site..................................................................................................................... 58
Figure 13. Mean percent cover (n = 24) of the most abundant non-native species and all
native species combined in the herb layer (A), shrub layer (B) and tree layer (C) with 95%
CIs. Vegetation surveys were conducted on 19 and 26 November 2015 in the Phase III
Restoration Site in Aldergrove Regional Park, BC................................................................................. 60
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LIST OF TABLES
Table 1. Control methods for invasive plant species pre-and post-construction of the
wetland complex and pond treatment. Two removal periods will occur pre-
construction and post-construction control is expanded in the maintenance
section (see Section 9.1 Vegetation Maintenance). ........................................................... 27
Table 2. Native wetland species to be included in the planting plan for the Phase III
Restoration Site. Plantings will occur around the Wetland Complex and Pond
treatments. ........................................................................................................................................ 41
Table 3. Timeline for restoration treatments to be implemented on the Phase III Site in
Aldergrove Regional Park, BC.................................................................................................... 50
Table 4. A comparison of nutrient levels to maximum acceptable levels that support aquatic
life (Ministry of Environment 2016). The sample was taken on 04 February 2016
from the pond on the Phase III restoration site in Aldergrove BC. ............................. 55
Table 5. Native species found on Phase III Restoration Site in Aldergrove Regional Park
during a pre-restoration baseline vegetation survey on the 19 and 26 November
2015. The species are presented in decreasing order of abundance. ........................ 61
Table 6. Proposed schedule for the Monitoring Plan of Phase III Restoration Site at
Aldergrove Regional Park in Aldergrove, BC. ...................................................................... 64
Table 7. Maintenance techniques for the re-vegetated areas surrounding the wetland
complex and pond on the Phase III site at Aldergrove Regional Park, BC................ 65
Table 8. A maintenance plan for the stabilized northern slope of the Phase III site in
Aldergrove Regional Park, BC.................................................................................................... 66
Table 9. Adaptive management plan for different hydrologic conditions that could
potentially negatively impact the wetland complex on the Phase III site in
Aldergrove Regional Park, BC.................................................................................................... 68
Table 10. A cost estimation for the Phase III Restoration at Aldergrove Regional Park, BC.69
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ACKNOWLEDGEMENTS
We would like to thank the owner of Balance Ecological Ltd., Monica Pearson, for her
enthusiasm for the project on and off the field, for sharing with us her experiences so that
we may learn from them and for providing us with the equipment; Aleesha Switzer for
showing us around site and for sharing her knowledge on the Oregon Spotted Frog; and
George Feddes for his historical knowledge of the area. We would also like to thank Eric
Anderson for his guidance on developing this report; Ken Ashley for his invaluable
knowledge on water quality issues; and Dave Harper for kindly giving us access to BCIT
equipment. Finally, we would like to thank the Metro Vancouver for giving us access to the
site and allowing us to conduct work.
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1. INTRODUCTION
Wetlands support substantial biodiversity and also provide essential ecosystem services
such as water purification, flood mitigation, food production, nutrient cycling, as well as
providing habitat for many species (MEA 2005, Zedler and Kercher 2005). In the Lower
Fraser Valley more than 70% of historical wetlands have been drained, diked, or in-filled,
leading to loss of the ecosystem services (Boyle et al. 1997). Most wetlands were lost to
agricultural conversion in Metro Vancouver, with similar losses in the Fraser Valley
Regional District (FVRD). The ultimate way to avoid continued loss of wetlands and
associated species is through conservation (Whigham 1999). However, for sites that have
already been degraded, wetland restoration and creation are increasingly common tools
for recovering some of the ecological functions associated with wetlands (Meli et al. 2014).
Aldergrove Regional Park is located in the Township of Langley, BC in the Lower Fraser
Valley. The boundary between Metro Vancouver district and FVRD bisects the park,
although Metro Vancouver is its sole owner and manager (Wilson 2010, Metro Vancouver
2013). The southern lowland portion of the park has been set aside for ecological
restoration as part of the Aldergrove Regional Park Management Plan (Fig. 1), focusing
mainly on restoring stream and wetland habitat (Metro Vancouver 2013; M. Pearson,
Balance Ecological Ltd., pers. comm. 2015).
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Figure 1. The southern lowland portion of Aldergrove Regional Park with key ecological restoration
and agricultural activities, in Aldergrove, BC. Gordon’s Brook, completed in 2010, is a constructed
side channel of Pepin Creek. Balance Ecological Ltd. is conducting a multi-phase wetland
restoration in the Phase I, II and III sites. Phase I was completed in 2013 and consists of a
constructed wetland. The restoration of the Phase II site was undertaken by BCIT/SFU Ecological
Restoration MSc students and is still in its planning stage. The Phase III site is the focus of this
restoration plan. Basemap: adapted from ArcGIS 2012 aerial photography, Inset: adapted from
Google Earth 2014 satellite imagery.
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Two restoration projects have already been initiated in the southern lowlands of
Aldergrove Regional Park. The first was the construction of Gordon’s Brook which is a
stream and wetland complex completed in 2010 (Fig. 1). The second is a three-phase
wetland restoration project led by Monica Pearson of Balance Ecological Ltd. Phase I was
completed in 2013, and entailed the construction of Pepin Marsh for the primary purpose
of providing habitat for the Oregon Spotted Frog (Rana pretiosa). More information
concerning Gordon’s Brook and the Phase I restoration is provided in Section 2.5.
MSc students in the joint British Columbia Institute of Technology and Simon Fraser
University Ecological Restoration program developed a restoration plan for Phase II. The
plan entailed wetland creation and two experimental treatments for controlling reed
canarygrass (Phalaris arundinacea). Planning for the Phase II site is still underway and a
start date for construction has not yet been established.
Phase III is the focus of this restoration plan which we are developing in collaboration with
Balance Ecological Ltd. The Phase III restoration site is located above the Abbotsford-
Sumas aquifer in the Bertrand watershed, 500 m east of Gordon’s Brook (Fig. 1; Mitchell et
al. 2003, Helfield and Lundgren 2012). The overarching goal of the Phase III Restoration
Project is to increase native biodiversity by expanding aquatic and wetland habitat. We
anticipate the Phase III wetland complex will be an expansion of the restoration work in
the Phase I and II sites, which will improve habitat value by increasing landscape
connectivity.
The Society for Ecological Restoration International (SERI) defines restoration as returning
a degraded, damaged or destroyed ecosystem to its historic trajectory and thereby
assisting in its recovery (SERI 2004). Historical conditions of the Phase III site are not
known, and thus this restoration project will entail enhancing the ecological conditions of
this site. Although this plan may not be considered restoration according to the SERI
definition it will be referred to as such throughout this report.
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2. SITE HISTORY
2.1. Glaciation
The Lower Fraser River drainage area was almost entirely covered by ice 15,000 yrs. BP
during the Fraser glacial period. The glacier retreated 13,000 yrs. BP to the eastern Fraser
Valley (Armstrong 1981). After deglaciation sea levels rose 175 m above today's level,
submerging the entire Lower Fraser Valley. This is evidenced by marine deposits
throughout the region (Mathewes et al. 1970). The minor Sumas glaciation event occurred
in the central Fraser Valley 11,500 yrs. BP and retreated around 9,000 yrs. BP (Saunders et
al. 1987). The drainage patterns produced by its retreat are similar to those present today
(Mackie et al. 2011).
2.2. Historical Human Presence
The Matsqui First Nation, a band of the Stó:lo-, is currently the only First Nation whose
traditional territory includes Aldergrove Regional Park (Metro Vancouver 2015). The
traditional territory of the Stó:lo- First Nation extends from Mud Bay in Tsawwassen to the
Fraser River east of Mission, and encompasses Stave Lake (CEAA 2014). Human presence
in the Lower Fraser Valley has been recorded in the Stave Watershed which contains the
Phase III site. Archeological remains found in the area were radiocarbon dated to 10,000
yrs. BP (McLaren et al. 2008). European contact in the Lower Mainland occurred in the late
1790s through explorations led by Captain George Vancouver (Thom 1999). Throughout
the 1800s the Lower Fraser Valley was heavily settled by people from southern Ontario
and the United States of America (USA). By 1941 more than 50% total land area in the
Lower Fraser Valley had been cleared for agriculture (Demeritt 1995).
2.3. Historical Ranges of At-risk Species
The northernmost extension of the Oregon Spotted Frog and Red-legged Frog (R. rana)
ranges occur in the southwestern corner of BC (Environment Canada 2014, COSEWIC
2002a). The Oregon Spotted Frog was listed as Endangered in 2000 by the Committee on
the Status of Endangered Wildlife in Canada (COSEWIC) and under the Species at Risk Act
(SARA) in 2005. It is provincially Red-listed in BC. The species is extirpated from 70% of its
known historical range, and as of 2010 only four known populations remained in Canada
15. 5
(COSEWIC 2000, Environment Canada 2014). The Red-legged Frog was designated as a
species of Special Concern in 1999 by COSEWIC and under SARA in 2005. Additionally, it is
provincially Blue-listed in BC (COSEWIC 2002a). Red-Legged Frogs have been documented
on the Phase I site (Aleesha Switzer, Balance Ecological Ltd., pers. comm. 2016). The
Western Toad (Anaxyrus boreas) is found throughout BC, including the Phase I wetland. It
was listed as Special Concern by COSEWIC in 2002 and under SARA in 2005, as well as
provincially Blue-listed in BC (COSEWIC 2002b). All of these amphibian species are
suffering from habitat loss, contributing to their declining numbers (COSEWIC 2000,
COSEWIC 2002a, COSEWIC 2002b).
The Salish Sucker (Catostomus sp.) range is restricted to a few watersheds in BC’s Fraser
Valley and northwestern Washington State (McPhail 1997). This species is evolutionarily
distinct from the Common Longnose Sucker (C. catostomus) from which it diverged
following its geographic isolation in southwestern BC during the Pleistocene glaciations
(McPhail and Taylor 1999, Pearson and Healey 2003). The Salish Sucker was listed as
Endangered in 1986 under COSEWIC and in 2005 under SARA (DFO 2015). The Coastal
Cutthroat trout (Oncorhynchus clarkii clarkii) has been documented in Pepin creek, and is
Blue-listed in BC (Metro Vancouver 2013, Costello 2008).
Restoration work in the southern portion of Aldergrove Regional Park has focused on at-
risk species with historical ranges that extend throughout the southern portion of the
Lower Fraser Valley. Restoring critical habitat has the potential to increase population
numbers for the above-mentioned species, whose main threat is habitat destruction.
Although they previously occurred throughout this region, there is no direct evidence these
species existed within the Phase III site. However, restoring the Phase III site presents an
opportunity to create and enhance habitat in a region where wetlands have been
previously lost and degraded.
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2.4. Park History
Aldergrove Regional Park is owned entirely by Metro Vancouver and was acquired
incrementally between 1967 and 1978 from the Township of Langley, receiving official
park status in 1969. The area has been used for farming, logging, gravel excavation, as well
as for hunting and other forms of recreation (Metro Vancouver 2013).
Agriculture was concentrated in the southern region of the park where it currently
continues to a limited extent. The small portion of park land now used for agriculture, is
licensed by Metro Vancouver as a complementary land management tool. This licensing is
aimed at supporting sustainable farming practices, facilitating public involvement and
providing learning opportunities. The agricultural use of the park also serves as a source of
park revenue (Metro Vancouver 2013). Agricultural activities in the region include haying,
livestock production, and berry farming (Cox and Kahle 1999).
2.5. Park Restoration History
Ecological restoration in Aldergrove Regional Park is being conducted in the southern
lowlands, in areas that were formerly used for agriculture. These areas are heavily
impacted by previous farming practices, particularly from hydrological alterations such as
draining and diking. This impact has made the restoration of stream and wetland habitat
necessary, in order to aid in the recovery of stream and wetland species.
Pepin Creek is an important ecological feature in the park, providing spawning and rearing
habitat for Coho Salmon (Oncorhynchus kisutch), Cutthroat Trout, the Threatened Nooksack
Dace (Rhinichthys cataractae), and the Endangered Salish Sucker (Pearson 2003, Metro
Vancouver 2013). In the 1990s Pepin Creek habitat was compromised when large sediment
deposits entered the stream from two gravel pits (Pearson 2000). Consequently, in 1999
University of British Columbia researchers along with local stewardship groups and
landowners implemented an experimental restoration of stream and wetland habitat
named Gordon’s Brook (Fig. 1; RTSS 2010). Gordon’s Brook is an old agricultural drainage
ditch that was converted into a side channel of Pepin Creek with associated wetland habitat
(Metro Vancouver 2013). The created habitat was quickly colonized by Salish Sucker,
Nooksack Dace, and Coho Salmon (Patton 2003).
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The Phase I restoration site (also referred to as Pepin Marsh) is a constructed wetland
adjacent to Gordon’s Brook created in 2013 by Balance Ecological Ltd. with support from
Metro Vancouver. The wetland was designed to provide habitat for the Oregon Spotted
Frog and it is currently being monitored to assess the habitat suitability for potential
translocations of this species (Metro Vancouver 2013, Pearson 2013). Additional goals of
the restoration include enhancing native biodiversity, contributing to research on marsh
restoration, and providing education and stewardship opportunities (Pearson 2013). The
wetland consists of areas that are permanently and seasonally inundated, with water levels
being maintained by a grade control structure installed at the wetland outflow. However, a
beaver dam at the wetland outflow is causing elevated water levels and impeding seasonal
drying of the ephemeral ponds. The wetland supports a variety of native emergent
vegetation, including sedges and cattails, although large areas of the wetland have been
overgrown by invasive plants, in particular reed canarygrass. Control practices for this
plant species have included manual removal (e.g. mowing) and herbicide application. Post-
restoration maintenance and monitoring of the Phase I site is being conducted by Balance
Ecological Ltd., and is focused on site hydrology, amphibian surveys and invasive plant
control.
2.6. Phase III Site History
The Phase III restoration site was historically used for agricultural purposes, but has not
been farmed since the early 1990s. The site and adjacent properties were likely used for
haying which was a typical land use for the southern lowlands of Aldergrove Regional Park
(Metro Vancouver 2013). This inference is based on aerial photos depicting uniform crops
that are typical of hay fields (Fig. 2). These historical photographs depict the site being used
for agriculture in the 1940s, but agricultural use likely began as early as 1908 when the
first farming families settled in the area (Metro Vancouver 2013).
18. 8
Figure 2. Historical photos depicting the agricultural uses in the Phase III restoration site in Aldergrove Regional Park, BC. Phase III is
outlined in red, and the blue oval and purple rectangle demark locations of a pond and an animal enclosure, respectively. The buildings in
the northern portion of the Phase III site include a family home and farming structures such as a stable and barn. The uniform vegetation
patterns shown in the photos from 1949, 1969 and 1988 are consistent with this site being used as hay fields. Photos dated from 1949-
1988 provided by Monica Pearson, photo dated 2004 adapted from Google Earth 2004.
19. 9
The Phase III site may have been more recently used as pasture, as horses were seen
grazing within the site under the previous land tenants (G. Feddes, Tenant, pers. comm.
2016). Additionally, aerial photos from 2004 show an unvegetated area which was most
likely an animal enclosure (Fig. 2). A pond was excavated in the southwest corner of the
Phase III site between 1949 and 1969 (Fig. 2). This pond may have functioned to retain
manure runoff from areas used by livestock given that ponds are used extensively in
agricultural lands to prevent surface water pollution (Alberta Agriculture and Rural
Development 2000). The pond is a good indication that livestock grazed on the site or in
upland pastures.
3. CURRENT PHASE III SITE CONDITIONS
3.1. Land Use and Infrastructure
To the east of the Phase III restoration site there is active farmland consisting of hayfields
and grazing land. To the north there is raspberry farmland that does not show signs of
recent cultivation (Fig. 1). These farms are currently under agricultural license for land
management purposes by Metro Vancouver (Metro Vancouver 2013). However, there is no
current land use occurring directly on the Phase III site, as the area is restricted to the
public and no longer used for agriculture.
Farming infrastructure on the Phase III site was removed in 2011, although evidence of
former human use is present. A driveway of compacted gravel runs through the western
portion and ends halfway up the northern slope (Fig. 3). It leads to a clearing where a
historical home was located, as indicated by the remains of a concrete foundation and
historical well classified for domestic water supply (Well Identification Plate Number:
33633; BC detailed well report n.d.). Utility lines run the length of the driveway and end at
the cleared historical home site. There are also buried utility lines that run alongside the
driveway, but we have not identified their northern endpoint. There are remnants of an old
wood and wire fence, where historical farm buildings (likely barns or stables) were
previously located. At the southern extent of the site there is an agricultural drainage ditch
running parallel to 0 Avenue. A second drainage ditch enters the site from the east, and
runs along the bottom of the slope (Fig. 3).
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Figure 3. Map depicting current and previous site attributes including infrastructure, topography,
soil pit locations, and hydrological features, of the Phase III site located in Aldergrove Regional
Park, BC. Soil pits were established by Balance Ecological Ltd. Contour lines were obtained from the
Township of Langley, GeoSource 2008.
3.2. Climate
Aldergrove Regional Park is in the Coastal Western Hemlock very dry mild biogeoclimatic
zone (CWHxm1), which is characterized by warm dry summers and wet temperate winters
(Pojar et al. 1991). Wetlands are common in the coastal lowlands of this zone (Ministry of
Forests 1999). The area receives mean annual precipitation of 1507.5 mm/year, which
comes mainly from rain and secondarily from snowfall (Environment Canada 2012).
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3.3 Topography
The Phase III site is 6 ha and slopes from 75 m above sea level in the northern section to 45
m in the southern section (Fig. 3). Most of the elevation change occurs in the north, where
there is a 22º slope. The southern portion of the site is relatively flat, with only 1 m of
elevation change. The site exhibits pronounced microtopography in the eastern part of the
site. There are higher elevated microsites and depressions that extend below the water
table.
3.4. Soils
According to Soils of the Langley-Vancouver Map Area (British Columbia Soil Survey
Report No. 15), Phase III has 40-160 cm of well-decomposed organic material with an
underlying layer of fine-textured glaciomarine deposits (Luttmerding 1984). These surveys
identified a perched water table, with very poor drainage. Soil data collected by Balance
Ecological Ltd. indicate significant variability in soil conditions across the Phase III site (see
Fig. 3 for soil pit locations; M. Balance, unpubl. data). The organic layer averages 40 cm in
depth across most of the site and in some areas reaches over 60 cm in depth. The dominant
soil texture across the site is sandy loam, with some areas of clay loam, silty sand, and
coarse sand. The A2 and A3 soil pits displayed mottling in the shallow mineral layers below
the organic component (40-140 cm), indicating a seasonally high water table. Water
seepage was witnessed between 140-180 cm depth in the A2, A3 and A4 soil pit during
excavation in the summer of 2015. Soil pit A1 revealed only a thin layer of topsoil over
gravel, perhaps because this soil pit is located where a historic animal enclosure previously
existed (Fig. 3).
3.5. Hydrology
The main hydrological features on the Phase III site include two drainage ditches and an
old agricultural pond. There is a drainage ditch flowing into the site from the east located
below the slope to the north, and the other is along 0 Avenue (Fig. 3). The pond is
approximately 30 m in length and 10 m in width. We measured a maximum pond depth of
1.56 m on 04 February 2016, and it does not appear to be highly variable during the fall
and winter season. Changes in depth will be measured throughout the spring and summer
22. 12
seasons to accurately assess water level depths (See section 8.1. Hydrology). The banks of
the ponds are extremely steep ranging from 1:1 to 3:1 horizontal to vertical slopes. The
ponds circumference is highly variable throughout the year, and overflows the banks
during high rain events. Precipitation appears to be the only surface water input. The pond
is typically separated from the drainage ditch along 0 Avenue, although after high rainfall
events the pond water level rises and flows into the drainage ditch.
The agricultural pond and drainage ditches function to dry out the site by collecting surface
water runoff and drawing down the water table. This was made apparent on 19 November
2015 when we observed that the Phase II and Phase III sites were completely inundated
with water because a beaver dam was blocking the drainage ditch along 0 Avenue, east of
the Phase II site. The driveway along the west edge of the site also acts as a berm that
prevents water from flowing between the Phase II and III sites. It will have to be removed
or culverted in order to reconnect the hydrology between the Phase II and III sites. There
are also likely drainage tiles present throughout the Phase III site, affecting the hydrology
of the site by increasing groundwater runoff. Drainage tiles act to remove standing water
from agricultural sites in order to improve cultivation practices.
The microtopography within the southern portion of the site creates a wetland complex
consisting of a series of ponds that have been filled with water for every site visit
throughout the 2016 winter season. The depressions are groundwater fed, receiving
surface water runoff from the drainage ditch entering the site from the east located below
the northern slope (Fig. 3). It is likely the surface water input only occurs during high
rainfall events. Due to the indication of a seasonally fluctuating groundwater table these
ponds may dry out in the hot summer months. We will conduct hydrology monitoring to
determine the seasonal variation in groundwater level (See section 8.1. Hydrology).
3.6. Water Quality
We gathered preliminary data on water temperature, dissolved oxygen (DO), and pH from
the agricultural pond on 19 November 2015. Water temperature and pH were within the
acceptable ranges for freshwater species for the time of year they were taken (CCME
1999b). Conversely, DO levels were <2 mg/L, well below acceptable levels for freshwater
23. 13
species in North America (i.e., >6-8 mg/L; CCME 1999b). We conducted testing on
additional water quality parameters on 04 February 2016. Our analysis of these results
indicated high levels of ammonia (NH3), nitrate (NO3-) and nitrite (NO2-), and total
phosphorus (TP) (see Section 8.2 Water Quality). The most probable number (MPN) of
colony forming units (CFU) in the pond on the Phase III site was 579 MPN/100 ml. There is
no direct conversion of MPN to CFU but there is a strong positive relationship between
MPN and CFU estimates (Cho et al. 2010, Sutton 2010). The MPN of CFU in the pond was
above the upper CFU threshold for recreation, irrigation, and drinking water (i.e., 200
CFU/100 ml, 100 CFU/100 ml, and 0 CFU/100 ml, respectively) (CCME 1999b).
3.7. Vegetation
The dominant plant species on the Phase III site are willow (Salix spp.), Himalayan
blackberry (Rubus armeniacus), and reed canarygrass (Fig. 4) (see Section 8.5 Vegetation
Surveys). The blackberry occurs mainly in disturbed areas where the old farm buildings
were located and on the slope in the northern portion of the site. These areas are likely
unsuitable for native plants due to compaction, poor soil quality and increased drainage.
Reed canarygrass dominates the flat southern portion of the site in areas that are
inundated and receive high levels of sunlight.
24. 14
Figure 4. Dominant vegetation on Phase III Restoration Site in Aldergrove Regional Park, BC based
on aerial photos and field surveys conducted on 19 and 26 November 2015. Balance Ecological
removed several blackberry patches on 21 December 2015. Figure adapted from Google Earth
satellite imagery (2014).
The mixed open forest in the southern portion of the site is comprised mainly of willow,
and secondarily of black cottonwood (Populus trichocarpa) and red alder (Alnus rubra). On
the steeper slope in the northern portion of the site there is a patch of large coniferous
trees consisting of Douglas-fir (Pseudotsuga menziesii) and western hemlock (Tsuga
heterophylla) surrounded by Himalayan blackberry. The black poplar (Populus nigra) that
are located on the slope were likely planted by earlier farming families, based on their
arrangement along the driveway.
25. 15
3.8. Fish and Wildlife
Several native at-risk species have been observed in the restored areas of Aldergrove
Regional Park. There have been fish documented in Pepin Creek and Gordon’s Brook
including Coho Salmon, Endangered Nooksack Dace, Endangered Salish Sucker, Stickleback
(Gasterosteidae sp.) and Cutthroat Trout. Amphibian species have been noted in the Phase I
wetland, including Red-legged Frog and Western Toad.
Taking the pond water quality sample results (i.e. low DO) into consideration, we assume
fish will not be detected. Baseline monitoring of fish will be conducted in April to confirm
this assumption. Even with low DO, during a site visit on 11 April 2016, Northwestern
Salamander (Ambystoma gracile) egg masses were observed in the pond (Appendix I).
Baseline monitoring will be used to indicate presence of additional amphibian species.
Throughout our site visits, we observed Great Blue Herons, and waterfowl (i.e. Mallards),
Red-tailed Hawks, Bald Eagles, coyotes, and small mammals (i.e. Microtus sp.) on the Phase
III site. Although there are no monitoring protocols put in place for birds and mammals, we
will continue using qualitative non-formal observations for noting presence.
4. STRESSORS
Through preliminary site assessment we have identified the following main stressors to the
Phase III restoration site: agriculture and associated hydrological alterations, invasive
species, slope erosion, and beavers (Castor canadensis). These are described in detail
below.
4.1 Agriculture and Hydrological Alterations
The greatest threat to at-risk Oregon Spotted Frog, Red-legged Frog, Western Toad and
Salish Sucker in BC are habitat loss due to agriculture and hydrological alterations
(COSEWIC 2002a, COSEWIC 2002b, COSEWIC 2012, Environment Canada 2014, SAR Public
Registry 2015). The Phase III site has significant habitat loss due to agriculture, including
associated changes in hydrology. In order to restore habitat for these species the impacts of
agriculture on the Phase III site will need to be mitigated.
26. 16
The Phase III site was used for agriculture until the 1990’s, and adjacent properties are still
being farmed. Land to the north of the site was historically licensed for raspberry farming
(Metro Vancouver, 2013). Most of the raspberry fields in the area are fertilized by poultry
effluent and commercial fertilizer, and also require irrigation in the dry summer months
(Mitchell et al. 2003). Presumably previous point-sources and current non-point sources of
fertilizer from adjacent agricultural sites have increased nutrient loading in soil and
groundwater of the Phase III site. High nitrate concentrations have been documented in the
Abbotsford-Sumas aquifer as a result of extensive agricultural practices in the Lower
Mainland (Zebartha et al. 1998, Mitchell et al. 2003). Additionally, we noted algal blooms
on the Phase I wetland on 01 October 2015, which could be a result of excess nutrients
from fertilizers entering the wetland, leading to eutrophication (Moxey 2012)
The results of the water quality test we conducted on 04 February 2016, indicated high
levels of nitrate, nitrite, ammonia, and total phosphorus (see Section 8.2 Water Quality).
These results are consistent with the hypothesis that the site is being contaminated by
fertilizer runoff from adjacent farms. Sources likely include agricultural run-off from farms
surrounding the Phase III site. Furthermore, water back-flowing into the pond from the
drainage ditch may also entail a non-point source of nutrients.
Analysis of our water quality results indicate the low water quality of the pond is due to
inputs of agricultural runoff containing high levels of ammonia, a compound used in the
majority of fertilizers. As ammonia oxidizes into nitrates and nitrites, the majority of
available DO is used (Suter et al. 2010). Oxidation of ammonia (i.e. nitrification) is likely
occurring in the pond on the site, indicated by high ammonia concentrations and extremely
low levels of DO (see Section 8.2.2 Water Quality - Results). Low DO concentrations can
decrease species diversity, and have lethal effects on freshwater aquatic fish and
amphibian species (CCME 1999b, de Solla et al. 2002, Camargo et al. 2005, Suter et al.
2010). Additionally, the benthic sediments of the pond contain high levels of ammonia (see
Section 8.3. Sediment Survey - Results), which can be toxic to benthic species (Suter et al.
2010). Elevated ammonia levels that are resulting in low DO will need to be mitigated to
enable colonization of the site by the target fish and amphibian species.
27. 17
The hydrological regime of the Phase III site has been altered due to the installation of the
two drainage ditches, drainage tiles and an agricultural pond (M. Pearson, Balance
Ecological Ltd., pers. comm. 2016). Prior to agricultural use the Phase III site likely had a
varying hydrological regime influenced by precipitation, topography and climate. The
ditches, tiles and pond now function to dry out the site and reduce seasonal fluctuations in
groundwater. Before the construction of the Phase I wetland, Balance Ecological Ltd. had to
deactivate drainage tiles that were found on site. The drainage tiles present on the Phase III
site, will need to be deactivated during the wetland expansion to restore the natural
hydrological regime.
4.2. Invasive Species
Invasion by non-native species is one of the top threats to biodiversity and ecosystem
function (Mack et al. 2000). Invasive non-native plants have the potential to reduce the
abundance and diversity of native plants (Levine et al. 2003). Thus, controlling the
abundant invasive plants on the Phase III site is an important component of this restoration
project.
We conducted baseline vegetation surveys on 19 and 26 November 2015 which showed
that the dominant plant species on the Phase III site are invasive Himalayan blackberry and
reed canarygrass (Fig. 4, see Section 8.5. Vegetation Surveys). While these species provide
some habitat in the form of food and cover, they also form large monocultures which
decrease overall habitat value. We documented additional non-native species on site, which
included morning glory (Calystegia sepium), creeping buttercup (Ranunculus repens),
Japanese knotweed (Fallopia japonica) and Canada thistle (Cirsium arvense). However,
control methods will be focused on the dominant Himalayan blackberry and reed
canarygrass.
Reed canarygrass is a perennial wetland plant that is highly competitive and grows rapidly,
making it an aggressive invader (Lavergne and Molofsky 2004). It spreads by production of
dense aboveground crowns and a thick matrix of underground rhizomes (Katterer and
Andren 1999). Through these mechanisms it generally forms dense monospecific stands
28. 18
that negatively affect local wetland plant and animal communities (Galatowitsch et al.
1999).
Himalayan blackberry has many morphological and physiological traits making it an
aggressive invasive plant species. This semi-evergreen biennial shrub can grow up to 3 m
high, and individual plants can expand laterally up to 7 m in a single season (Bennett
2006). Himalayan blackberry reproduces by seed in the late spring. It can also reproduce
vegetatively throughout the year by forming roots at stem tips, which spread outward to
form daughter plants (ISCBC 2014). It is shade intolerant and therefore is rarely found in
dense forests (Bennett 2006).
Himalayan blackberry has become naturalized throughout the Pacific Northwest, including
in BC (Boersma et al. 2006). Evidence of naturalization has occurred on the Phase III site.
For instance, we observed numerous bird nests within the blackberry thickets during the
November 2015 site visits. The naturalization of Himalayan blackberry on the site means
control methods may be limited. For example, removal methods must be conducted outside
the nesting season of birds, and native plantings should be used to replace habitat provided
by blackberry.
The presence of non-native invasive fish and wildlife has not been confirmed on the Phase
III site, although several species have been identified on the adjacent Phase I area. These
include American Bullfrog (Lithobates catesbeianus) and Yellow Pumpkinseed (Lepomis
gibbosus). We will use pre-restoration baseline monitoring to inventory species of invasive
amphibians and fish (see Section 8.6 Amphibian Surveys, and Section 8.7 Fish Surveys).
4.3. Slope Erosion
The steep slope on the northern part of the Phase III site is likely vulnerable to erosion,
which would increase sedimentation of the wetland (Skagen et al. 2008). There is evidence
of erosion on the path up the slope. Slope erosion or hillslope failure can result in harmful
levels of sediment inputs to wetlands. Sedimentation can negatively affect fish, amphibians
and invertebrate populations by reducing oxygen levels in the benthic layer (Erman and
Ligon 1988). A hillslope failure like a debris flow could compromise important structural
29. 19
features of the wetland located down slope. Thus, erosion control will be implemented on
the slope above the expanded wetland (see Section 7.6.2. Slope Stabilization).
4.4. Beaver
There are numerous beaver dams in the southern portion of Aldergrove Regional Park. One
of the dams was constructed in the Phase I wetland thereby flooding the ephemeral
marshes (M. Pearson, Balance Ecological Ltd., pers. comm. 2015). Another dam constructed
in the drainage ditch running along 0 Avenue in November 2015, has flooded both the
Phase II and Phase III sites (G. Feddes, tenant, pers. comm. 2016). There is also evidence
that beavers are using the Phase III restoration site. We saw several felled trees during our
site visits on 19 and 26 November 2015 (Appendix II). The creation of a beaver dam in the
Phase III wetland could lead to flooding of the ephemeral wetland complex that we have
proposed for this site, or create a migration barrier for Salish Sucker and Coho Salmon.
5. DESIRED FUTURE CONDITIONS
Due to the extensive impacts to wetlands within the Fraser Valley there are no local sites
that can be used as references for pre-degradation historical conditions (M. Pearson,
Balance Ecological Ltd., pers. comm. 2015). Thus, reference conditions for this restoration
project will focus on literature review of parameters for ecologically functional wetlands.
There are well-established published values for water quality parameters, that will be the
main targets. The Phase I restoration will also be used as a tool for developing adaptive
management strategies in regards to hydrological maintenance and beaver activity. We
anticipate that these two factors will impact the Phase III site post-restoration, given their
impacts to the Phase I wetland, such as flooding due to beaver activity.
Gordon’s Brook, and the Phase I and II sites are covered extensively with reed canarygrass.
An experimental study on reed canarygrass removal is proposed for the Phase II site.
Results from that experiment, if proven effective, will be implemented on the Phase III site.
We intend to establish habitat connectivity between the Phase I, II, and III sites while also
increasing landscape heterogeneity by creating different types of specialized habitat in the
Phase III site for target native species. Oregon Spotted Frog, Red-legged Frog, Western
30. 20
Toad, Cutthroat Trout and Salish Sucker are the five at-risk species whose presence is
desired on the Phase III restoration site. The Salish Sucker, Cutthroat Trout, Red-legged
Frog and Western Toad have been observed in Aldergrove Regional Park and their habitat
requirements will guide restoration prescriptions (Metro Vancouver 2013). Furthermore,
Phase III has the potential to support translocations of the Oregon Spotted Frog, or
colonization of this species from the Phase I site should translocations to that site occur. As
Oregon Spotted Frogs are indicator species for healthy, shallow and warm wetlands their
presence is desired (Environment Canada, 2014).
Overwintering juvenile Coho Salmon are also desired on site. Coho have been observed
spawning in Gordon’s Brook as well as in the ditches along 0 Avenue (G. Feddes, Tenant,
pers. comm. 2016). A study assessing restored habitat for Coho Salmon in the Lower Fraser
Valley found that the sites were also beneficial for other at-risk freshwater species
(Branton and Richardson 2014). Specifically, listed-species richness was positively
correlated with Coho abundance, indicating their suitability as umbrella species for
restoration of freshwater habitat. We will design the Phase III wetland to include Coho
habitat features that may increase viable habitats for listed species within the Lower Fraser
Valley. Other habitat requirements that are species-specific will also be incorporated.
Finally, the desired vision for the Phase III restoration site will take into consideration the
goals of the Aldergrove Regional Park Management Plan (Metro Vancouver 2013). The plan
has as an ecological and conservation goal to “create conditions for ecological diversity and
resilience over the long-term [...] and recognize the potential of the park to provide
valuable ecological services and habitat for species at risk” (pp. 33). The Phase III
restoration plan will help advance this goal as it entails creating wetland habitat for species
at risk. Additionally, the Park Management Plan has proposed opening up the southern
lowlands of the park for public access and increasing park infrastructure in this area. This
includes the construction of a pedestrian path running east-west on the northern part of
the Phase III site. We will incorporate this planned path and public access in our
restoration treatments and public outreach (see Sections 7.6. and 12 respectively).
31. 21
6. RESTORATION GOALS AND OBJECTIVES
To fulfill the following goals and objectives a variety of restoration treatments will be
applied to the Phase III site. We will expand the current wetland present in the eastern side
of the site to help achieve the overall goals to increase native flora and amphibian species
(Fig. 5 treatments). The agricultural pond currently present on site will be expanded,
regraded, and planted to focus on fulfilling the goal to increase native freshwater fish
species. The removal of invasive plant species, and establishment of native plant species is
also an important aspect of this restoration plan. Additionally, we will stabilize the slope at
the northern end of the site to help manage slope erosion following invasive removal.
Finally, other plans include incorporating a willow farm and pollination garden in the
Phase III site (Fig. 5).
Goal 1: Mitigate water and sediment quality in existing agricultural pond to
acceptable parameters for free swimming organisms in freshwater habitat
Objective 1.1: Increase dissolved oxygen to between 6-8 mg/L by promoting
denitrification of ammonia in the benthic sediment and water.
Action 1.1.1: Incorporate microtopography features to promote nutrient
cycling by creating small elevation changes (30-50 cm) throughout the
expanded benthic area of the pond.
Action 1.1.2: Increase microbial population size, to increase denitrification
activity by applying compost in the permanently wetted area, emergent and
riparian wetland areas prior to the native planting treatment.
Action 1.1.3: Increase nutrient uptake by planting a diversity of emergent
wetland vegetation (i.e. rushes, Cattail and sedges). Planting densities in the
emergent area are 1/m2.
Goal 2: Expand suitable habitat for at-risk fish species in the southern lowlands of
Aldergrove Regional Park, focussing on Salish Sucker, Juvenile Coho Salmon and
Cutthroat Trout in particular.
Objective 2.1: Excavate existing agricultural pond after monitoring spring and
summer hydrology to ensure a minimum annual depth of 70 cm which is the target
depth for Salish Sucker (RTSS 2010).
Objective 2.2: Regrade the steep banks of the existing agricultural pond on the Phase
III site to make them more gradual. Target bank slope is 15:1 – 20:1 horizontal to
vertical (Kentula et al. 1992).
32. 22
Objective 2.3: Establish 25-50% cover of emergent vegetation in existing
agricultural pond on the Phase III site for Salish Sucker daytime security cover
(Pearson and Healey 2003).
Objective 2.4: Install large woody debris, boulders, and gravel to the existing
agricultural pond on the Phase III site to create juvenile Coho, and Cutthroat Trout
habitat (Cederholm et al. 1997).
Goal 3: Expand suitable habitat for at-risk amphibian species in the southern
lowlands of Aldergrove Regional Park, focussing on Oregon Spotted Frog, Western
Toad and Red-Legged Frog.
Objective 3.1: Expand wetland complex located in the southeast portion of the Phase
III site by exaggerating existing microtopography (Fig. 5). Seasonal drying is
favoured by the life histories of native amphibians and will inhibit Bullfrog
colonization (Washington Department of Fish and Wildlife 2016). Excavation depths
will be determined following groundwater hydrology monitoring (see section 8.1
Hydrology)
Objective 3.2: In constructed ephemeral ponds establish 25–50% emergent
vegetation cover required for breeding habitat of Oregon Spotted Frogs
(Environment Canada 2014, Watson et al. 2003).
Objective 3.3: Plant Hardhack (Spiraea douglasii) around constructed ephemeral
ponds. Hardhack has been shown to provide good overwintering habitat for native
amphibian species (Watson et al. 2003). Planting densities 2/m2.
Goal 4: Increase cover of native plant species in the emergent, riparian and upland
areas surrounding the enhanced agricultural pond and expanded wetland complex.
Objective 4.1: Establish emergent vegetation by seeding with 1000 kg/ha, and
planting 20-30 cm plants every 1/m2.
Objective 4.2: Establish riparian vegetation by seeding with 800 kg/ha and planting
one plant every 2 m2 (assuming 4 L pots).
Objective 4.3: Establish upland vegetation by planting and staking large shrubs and
live stakes to maintain the standing swamp characteristics currently present on site.
Live willow stakes and cuttings will be spaced at 1/m2, and shrub plantings will
occur every 2 m2.
Goal 5: Increase wetland habitat connectivity in the southern lowlands of Aldergrove
Regional Park.
Objective 5.1: Deactivate the driveway separating the Phase II and Phase III sites by
the installation of culverts. Suitable number of culverts will be determined following
further site investigation.
33. 23
Goal 6: Reduce cover of non-native invasive plant species with specific focus on reed
canarygrass and Himalayan blackberry.
Objective 6.1: Reduce reed canarygrass cover over entire Phase III restoration site
by mowing (Kapust et al. 2012). We will do pre-restoration surveys to determine
current cover of reed canarygrass and to establish appropriate removal rates.
Objective 6.2: Reduce Himalayan blackberry cover over the entire Phase III site
through a phased treatment plan. Approximately 20% was removed on 21
December 2015 by Balance Ecological Ltd. We will do additional surveys to
determine post-removal cover of Himalayan blackberry to establish future removal
rates.
Objective 6.3: Establish native species to mitigate plant regrowth by seeding at 800
kg/ha, and planting natives to 1/m2 after invasive removals.
Goal 7: Stabilize slope at the north side of the Phase III site prior to trail construction
outlined in the Aldergrove Park Regional Management Plan (Metro Vancouver
2013).
Objective 7.1: Conduct soil moisture surveys on all sections of the slope to assess
survivability of live stakes, and wattle fencing.
Objective 7.1: Remove Himalayan blackberry by manual and mechanical methods in
a phased approach from the top to bottom of the slope. After removal, apply an 18
cm layer of mulch on the slope to prevent regrowth and erosion.
Objective 7.2: If soil moisture is suitable for soil bioengineering devices, install
wattle fences, and live staking to stabilize slope.
Goal 8: Expand suitable habitat for native pollinators on the Phase III site.
Objective 8.1: Plant native flower and shrub species in a pollination garden.
Objective 8.2: Install one bee box.
Goal 9: Increase native biodiversity in the Phase III restoration site.
Objective 9.1: Increase abundance and diversity of native fish species in constructed
pond habitat following the completion of Goal 1 and 2 (and associated Objectives).
We will do pre-restoration surveys to determine baseline native species abundance
and diversity.
Objective 9.2: Increase abundance and diversity of native amphibians in the
constructed wetland habitat following the completion of Goal 3 (and associated
Objectives). We will do pre-restoration surveys to determine baseline native species
abundance and diversity.
Objective 9.3: Increase abundance and diversity of native pollinator species
following the completion of Goal 8 (and associated objectives). We will do pre-
restoration surveys to determine baseline native species abundance and diversity.
34. 24
Objective 9.4: Increase cover of native plant species by planting and seeding
(Objectives 4.1, 4.2) as well as through natural colonization of native emergent,
riparian and upland plant species.
Goal 10: Increase public involvement and community awareness in accordance with
the Aldergrove Regional Park Management Plan (Metro Vancouver 2013).
Objective 10.1: Provide opportunities for education and stewardship by involving
organisations such as the Langley Environmental Partners Society and the Fraser
Valley Regional Watersheds Coalition in restoration efforts (see Section 15).
Objective 10.2: Enhance opportunities for research in wetland restoration and
native species recovery (see Section 15).
Objective 10.3: Provide opportunities for guided tours throughout the restored
wetlands in Phase I, II, and III following completion of all restoration activities in the
southern part of Aldergrove Regional Park.
35. 25
Figure 5. Map of proposed restoration treatments and their locations. The agricultural pond will be
expanded and enhanced to provide fish habitat. The wetland complex will be expanded by
exaggerating the existing microtopography consisting of wetted depressions and dry, elevated
mounds. Slope stabilization will occur in phases with Himalayan blackberry removal (see Section
7.6 Northern Slope Invasive Removal and Stabilization). The orange line delineates a future trail
proposed in the Aldergrove Regional Park Management Plan (2013).
36. 26
7. RESTORTION TREATMENTS
7.1. Control of Non-native Invasive Plants
The removal and control of invasive plants is an important component for the Phase III
restoration site. In general, pre-restoration site preparation will involve removal of existing
vegetation and seedbank by manual/mechanical removal, herbicidal treatment, topsoil
removal, or solarization (i.e. covering with black sheeting). Due to a shallow water table
and the close proximity of surface water, herbicide use will be limited. Additionally,
herbicide use should only occur prior to wetland construction in order to avoid herbicides
from entering the wetland and associated riparian areas. Control of invasive plants will
expand the areas where removal has already occurred (Fig. 4).
The two most abundant invasive plants on site are Himalayan blackberry and reed
canarygrass (see Section 8.5.2 Vegetation Survey - Results). Targeted control methods will
be used prior to wetland construction, with ongoing maintenance and monitoring
occurring post-construction. The optimal removal technique and preferred timing differs
for these species as well as by location (Table 1). Details of these techniques are described
in the subsequent sections.
37. 27
Table 1. Control methods for invasive plant species pre-and post-construction of the wetland
complex and pond treatment. Two removal periods will occur pre-construction and post-
construction control is expanded in the maintenance section (see Section 9.1 Vegetation
Maintenance).
Species Timing Location Removal method
Reed
canarygrass
Pre-construction
(completed 21 December
2016)
Southern lowlands
targeted for wetland
construction
Sod stripping
Pre-construction during the
month of July 2016
Areas where
regrowth occurs
Glyphosate
application
Post-construction in the fall
(see Section 9.1. Vegetation
Maintenance)
Areas where
regrowth occurs
Solarization
Himalayan
blackberry
Pre-construction
(completed 21 December
21)
Southern lowlands
targeted for wetland
construction
Manual and
mechanical removal
Pre-construction during the
month of May 2016 prior to
flowering
Areas where re-
growth occurs
Manual removal
Post-construction in the
spring (see Section 9.1.
Vegetation Maintenance)
Areas where
regrowth occurs
Manual and
mechanical removal
7.1.1. Reed Canarygrass Removal
Understanding the plant biology (i.e. physiology, life history, growth rate) of invasive plant
species is critical to developing an effective integrated invasive management program
(Masters and Sheley 2001). The physiological characteristics of reed canarygrass (e.g.
rapid growth, dense crowns, monospecific stands) require removal methods that target its
below ground mass, such as solarization, herbicide application, and sod stripping (see
Table 1) (Apfelbaum and Sams 1987, Apostol and Sinclair 2006).
Solarization entails heating the plant and its roots under black plastic, or a shade cloth until
the vegetation and roots are eradicated (Apostol and Sinclair 2006). Herbicide applications
38. 28
should occur in late August and September. This timing enhances Glyphosate translocation
to rhizomes, and results in higher reduction of belowground biomass (Adams and
Galatowitsch 2006). Alternatively, sod stripping can be an effective way to reduce reed
canarygrass cover (Apostol and Sinclair 2006). This method entails removal of
aboveground growth and several inches of topsoil and roots. The sod removed is then
rolled up and hauled away.
The main limitations of solarization and sod stripping are that they can be costly and
require lengthy implementation periods. Solarization requires the cover sheet to remain in
place for an entire growing season (over one year) (Tu 2006). Sod stripping requires the
use of heavy machinery like an excavator and dump truck for proper disposal.
An invasive removal was conducted on 21 December 2016 by Balance Ecological (Fig. 4)
There was minimal removal of reed canarygrass (10%) in the areas where the excavator
was used to remove blackberry. We will conduct further site assessments the area where
wetland complex and pond expansion is occurring for reed canarygrass regrowth, in May
2016 (Fig. 5). We will remove the regrowth and remaining patches in July 2016 (Table 1).
Removal methods for regrowth and remaining patches will include manual or mechanical
removal (sod stripping and mowing), solarization, and spot-spraying with herbicide where
appropriate (Tu 2006).
7.1.2. Himalayan Blackberry Removal
Balance Ecological Ltd. removed approximately 20% of the blackberry on the southern
portion of the Phase III site on 21 December 2016 (Fig. 4). The large thickets with the roots
and some topsoil were removed by an excavator. In areas where the excavator could not
safely enter the canes were manually cut and the roots were removed with shovels. All the
cuttings were left on site in large bundles, or placed at the bottom of the northern slope for
future removal by Metro Vancouver. The bundles left on site will be fed through a
mechanical chipper and used as mulch on the Phase III site.
We will conduct further site assessments in May 2016 to assess the extent of regrowth in
these areas. The regrown areas will be manually removed in the late spring prior to
flowering and will also be chipped and used as mulch on the Phase III site.
39. 29
7.2. Wetland Expansion Treatments
A wetland constructed on the Phase III site will satisfy the goal of creating a wetland
complex to increase habitat heterogeneity across the southern lowlands of Aldergrove
Regional Park. The existing ponds located on the Phase III site (excluding the excavated
agricultural pond) are characteristic of a swamp type wetland. Swamps are wetlands
dominated by trees and shrub vegetation communities, occurring in areas with varying
microtopography (Mitsch and Gosselink 1993, Mackenzie and Moran 2004). In British
Columbia, swamps are typically smaller components of larger wetland complexes
(Mackenzie and Moran 2004). Therefore, expansion of the existing swamp habitat on the
Phase III site will be an addition to the wetland complex already present in Gordon’s Brook
and the Phase I site.
7.2.1. Site Selection
The first stage in wetland project design is site selection (NOAA 2003). This entails
assessing the hydrology, topography, soils and biotic components of the proposed site
(Hammer 1992). These characteristics will dictate the wetland design, including size,
depth, water source, vegetation and ultimately function. Level ground (<6% slope) and an
area with a diameter of around 18 m is required for building a wetland that appears
natural. The large area is needed to accommodate the excavated soil and for the creation of
natural looking berms (Biebighauser 2011). The majority of the Phase III site is flat with
<1m elevation change and large enough (6 ha) to accommodate a created wetland.
The hydrological condition of the Phase III site is controlled primarily from agricultural
infrastructure, specifically the two drainage ditches on site (see section 3.5 Hydrology).
Currently, these ditches are increasing the surface water input into the site, because of
increased runoff from upland areas and a beaver dam impeding the outflow of water. This
increase in runoff and decrease in outflow has functioned in inundating the site for the
entirety of the 2016 winter season (November - April). This is evidenced by the water table
being at ground level of the water monitoring wells on each site visit. The only area which
is currently dry is a higher elevated area in the Northwest corner of the site. This area was
dominated by Himalayan blackberry, which was removed by Balance Ecological on 21
December 2015. It is now bare soil with some grass regrowth. This area, although free of
vegetation, will not be a suitable area for wetland construction because of its high
40. 30
elevation. Too much excavation will be necessary to create a naturally fluctuating
hydroperiod within this area.
It is likely that the Phase III site has a seasonally wetted hydroperiod: becoming saturated
in the wet winter months and drying out during the summer due to fluctuations in the
groundwater table. Although the southern portion of the site is relatively flat, there is lots
of variation within the microtopography creating alternating wet and dry areas. There are
natural depressions in the site which have been filled with standing water over the winter.
These depressions are mostly at the base of trees and are groundwater fed. In the dry
summer months the depressions will likely dry up as the water table drops. The majority of
the standing water and depressions are found in the southwest portion of the site.
Extensive hydrological monitoring will need to be completed prior to wetland construction
to confirm the hypothesis of a seasonally fluctuating water table and to determine the
variation in depths (see section 8.1. Monitoring - Hydrology).
The soils across the Phase III site are highly variable (see Section 3.4. Soils). The soil
textures consisting of high silt and clay concentrations would be able to accommodate a
surface water wetland. The sandy soils with high drainage would not hold any surface
water runoff, therefore cannot be excavated for a created wetland. Due to the high water
table and limited amount of surface water input the created wetland will be groundwater
fed, making soil texture negligible.
Based on the hydrological condition and microtopography, the wetland will be constructed
in the southeast portion of the Phase III site (Fig. 5). These areas already contain standing
water in winter months which will limit the amount of excavation needed. Additionally, due
to the high water table the excavated wetland will expose the groundwater making soil
texture negligible. The main constraints on wetland placement is the large amounts of
native woody vegetation present in this area. This vegetation may act as a barrier to
movement for the heavy machinery. The placement of the constructed wetland will ensure
that only a minimal number of these trees and shrubs need to be removed to ensure the
wetland retains swamp characteristics. After the wetland is constructed the woody
vegetation will provide habitat value and contribute to overall landscape heterogeneity.
41. 31
7.2.2. Wetland Design
The created wetland design consists of an expansion of the ponds already present in the
southeastern portion of the site. The expansion will involve creating a wetland complex of
interconnected ephemeral ponds. As discussed above the existing ponds exhibit swamp
like characteristics, therefore the new ponds are designed to maintain and expand the
existing swamp habitat. Currently there are seven wetted depressions on the Phase III site,
excluding the excavated agricultural pond. Most of the existing depressions are associated
with uprooted trees and standing trees. We will excavate the ephemeral ponds in grassed
areas between clumps of woody vegetation and existing depressions. These areas are
dominated by invasive species, primarily reed canarygrass and Himalayan blackberry,
therefore limited native vegetation removal will be necessary. These areas receive more
sunlight which will promote the growth of emergent and riparian vegetation. Although the
woody vegetation will be retained to offer some shading, thus reducing the chances of the
ponds drying out to early. The wetland complex will be connected through the flow of
groundwater with the potential for surface flow connection during storm events.
7.2.2.1 Amphibian Habitat Requirements
In order to accommodate the aforementioned amphibian species their habitat
requirements will be taken into account in the wetland design. The Oregon Spotted Frog
prefers warm water marshes, and large open water areas with some emergent vegetation
cover. They appear to avoid areas with gravelly substrates preferring fine silty sediment
(Environment Canada 2014). Red-legged Frogs require wetlands less than 50 cm deep with
suitable vegetation for egg mass deposition. Although these species are semi-terrestrial,
open water must be available for reproduction and juveniles undergoing development
(COSEWIC 2002a, Environment Canada 2014). Western Toads have broader habitat
requirements than the other two target amphibian species. They breed in warm shallow
waters, depositing their eggs in >1 m water (COSEWIC 2002b). The tadpoles of all the
species metamorphose in late summer but may grow faster in warmer water. However, the
species can only tolerate temperatures up to 21oC before mortality (COSEWIC 2000,
COSEWIC 2002a).
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7.2.2.2 Hydrology
Establishing appropriate hydrology is the most important feature of wetland design
because it dictates the structure and function of the created wetland (Mitsch and Gosselink
1993). The primary goal is to design a wetland that has a hydroperiod that favors the life
histories of native species and hinders the establishment of invasive non-native wildlife.
Additionally, establishing a hydroperiod that maintains the swamp characteristics of the
site is a key goal. The excavated depth of the ponds will determine the hydrological regimes
of the constructed groundwater wetland.
The depth of the constructed wetland will be suitable for native amphibians including the
Oregon Spotted Frog, Red Legged Frog and Western Toad. This will expand the amount of
suitable habitat for each species, aiding in their recovery. Native amphibians can withstand
a seasonally dry hydroperiod, therefore the created ponds will be ephemeral, drying out in
late summer. To ensure complete development of juveniles the ephemeral ponds will
contain a maximum of 50 cm of water for the entirety of metamorphosis (March-July)
before drying out. Additionally, the seasonally dry hydroperiod will inhibit the colonization
of Bullfrogs, which require permanent water to undergo metamorphosis (BC Frogwatch
n.d.). The ephemeral areas will be excavated to an appropriate depth between the high
water mark and the low water mark to ensure the late summer dry out (Mitsch and
Gosselink 1993).
Swamps typically occur in areas that have a semi permanent high water table and surface
water input (Mackenzie and Moran 2004). The microtopography of swamps allow trees
and shrubs to root in higher elevated areas surrounded by low wetted ponds. This pattern
is already displayed in the southeastern portion of the site. Therefore, we will increase the
microtopography by using excavation to create low seasonally wetted areas and high dry
areas where woody vegetation can establish. The groundwater filled depressions will
fluctuate seasonally dependent on precipitation levels and summer drought periods but
will be designed to be wetted in the winter and drying out by late summer. The excavated
depths will be finalized following hydrology monitoring, which should provide indication of
the seasonal variation in groundwater (see Section 8.1. Monitoring - Hydrology).
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7.2.2.3 Habitat Features
Wildlife features will be added to the created wetland in order to enhance its habitat value.
Any trees that had to be removed during the construction process will be replanted along
the water periphery in higher elevated areas. If space is limited we will place the extra
trees, preferably with root wads still attached, around the wetland as large woody debris.
We will add conifer logs as well as large boulders around the water's edge to provide cover
for native amphibians. The woody debris and boulders will provide substrate for
macroinvertebrates, providing food for amphibians (Biebighauser 2011).
7.2.3. Wetland Construction
Wetland construction will occur in the fall (beginning in August 2016) and will follow the
guidelines outlined in Beibighauser (2011). We will set aside an area two times the
expected water surface area for excavation, providing suitable space for the excavated soil.
Preparation of the site prior to excavation will include invasive control (see Section 7.1
Control of Non-native Invasive Plants). We will delineate the expected wetted areas, by
marking the periphery of the ponds to be excavated. Any native woody vegetation that is
within the wetland area will be removed with the excavator and then added to the wetland
periphery following construction. Trees not within the wetted areas will be left and
avoided by the excavator.
We will set up a level with full view of the construction site, in an area that will not be
disturbed. We will record elevations of the wetland boundary markers to ensure the
change in elevation between the inflow and outflow of the wetland is no more than 0.6 m.
The lowest elevation along the marked edge will be used as a reference for the maximum
depth of the constructed ponds. Prior to excavation we will remove the topsoil from the
wetland area so it can be added to the wetland periphery following construction. We will
excavate the seasonally dry ponds to between the low and high water mark. Once the
desired depth is achieved the excavator should create a gradual slope from the maximum
depth towards the wetland edge to create a naturally-shaped depression. Throughout the
excavation process we will systematically check the elevation to ensure the desired depth
is achieved.
We will use the soil removed from the depressions to create higher elevated
microtopography surrounding the excavated ponds. Once construction of the ponds
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completed, we will spread the topsoil initially removed from the area around the wetland
and microtopography. These areas will then be prepared and planted with native plants
(see Section 7.5. Installing Native Vegetation). Lastly, habitat features will be added to the
wetland.
7.3. Pond Enhancement
7.3.1. Pond Design
The pond located on the Phase III site, is a man-made agricultural pond that is currently
unsuitable habitat for freshwater aquatic species and emergent vegetation. We will
examine the hydrological changes during dry summer months to guide further changes in
pond depth. Based on this monitoring we will regrade and expand the pond in order to
increase the survivability of planted vegetation, and also the colonization of native
emergent and riparian vegetation. Furthermore, due to the unacceptable water quality
parameters measured in the pond (see Section 8.2.2 Water Quality - Results), we will
implement treatments to promote denitrification. The rationale for such design features
stem from the high levels of ammonia, nitrate, and nitrite in the pond leading to severely
low levels of DO. We will also include habitat features for Salish Sucker, Coastal Cutthroat
Trout and Coho Salmon, to enhance habitat characteristics associated with these
freshwater fish species. These treatments will occur concurrently with the expansion of
wetland complex in August 2016. The pond will not be connected to the expanded wetland
by created channels, but has the potential to be hydrologically connected through
groundwater and during high rainfall events.
7.3.2. Hydrology
The pond is located in the southwest corner of the Phase III site, and currently outflows
directly into the drainage ditch along 0 Avenue (Fig. 3). The pond is designed to be isolated
from the drainage ditch, although during heavy rainfall events water levels rise in both the
ditch and pond and form a connection. The pond's depth was 1.56 m at its deepest point
(measured 04 February 2016), and its area is highly variable. This variability occurs with
changes in precipitation, as surface water and overflow from the drainage ditch appears to
be primary input into the pond.
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Establishing the hydrological characteristics during the dry summer months is essential to
maintain adequate water levels. Maintaining water in the pond during low flow periods will
increase the survivability of emergent vegetation, and provide refuge for Salish Sucker,
Cutthroat Trout and Coho Salmon. We will implement a water level gauge in the pond in
April 2016 to assess changes in water levels of the pond during the spring and summer
season (see Section 8.1 Monitoring - Hydrology). This information will inform whether the
pond depth needs to be increased to maintain suitable water levels for the desired
freshwater fish species (see section 7.3.5 Freshwater Fish Habitat Requirements).
7.3.3. Regrading and Expansion
The bank slope of the pond are currently very steep ranging between 1:1 - 3:1 horizontal to
vertical (H:V). The steep banks are unstable, and limit the colonization and growth of
emergent vegetation. There is also limited area for riparian vegetation because the change
from the inundated pond to upland dry area is severe. This creates a narrow ring around
the pond suitable for riparian vegetation.
We will therefore expand the riparian area of the pond by creating lobes (Fig. 6). This
expansion will also allow for regrading of the banks. The ideal range for bank slopes is
between 15:1 - 20:1 H:V. Gentle bank slopes are more characteristic of natural wetlands,
and suitable for native emergent vegetation colonization (Kentula et al. 1992). This will
also increase the area suitable for riparian vegetation from a narrow ring to a more
complex riparian buffer. The expansion and regrading will occur primarily to the north and
east side of the pond. The south and west sides are bounded by the ditch and driveway
respectively, limiting expansion in these area (Fig. 6).
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Figure 6. Schematic of the pond expansion and regrading treatment to be implemented on the
Phase III Restoration Site, at Aldergrove Regional Park BC. The dark blue area marks the
permanently wetted area, and the light blue area marks the bank. In schematic A. the 1:1 is the
horizontal to vertical (H:V) slope of the banks currently present. In schematic B. the 15:1 and 20:1
represent the desired H:V slope after regrading and expansion of the pond.
7.3.4. Promoting Denitrification
During expansion and regrading we will create features to increase microtopography
within pond benthic and riparian area. Microtopography in wetlands form areas of aerobic
and anaerobic conditions which help improve biogeochemical cycling, like denitrification
(Moser et al. 2007). We will incorporate ranges of elevation during construction, the
maximum vertical change being 0.5 m. We will also ensure the surface soil in the pond and
riparian areas remains rough and loose.
There are two biological ways nitrogen can be removed in aquatic systems (1) it can be
temporarily retained through primary production of vegetation (2) it can permanently
removed through denitrification by anaerobic heterotrophic bacteria (Poe et al. 2003).
Denitrification helps mitigate the impact of nitrogen rich agricultural runoff in aquatic
47. 37
systems, by transforming nitrates and nitrites into gaseous nitrogen (N2) and nitrous oxide
(N20, Saunders and Kalff 2001). A study conducted by Sutton-Grier et al. (2009) found the
addition of compost amendments increased microbial population size, subsequently
increasing microbial denitrification activity. Their results suggest that compost
amendments are an effective treatment to stimulate nutrient cycling in nutrient rich
aquatic systems. We will therefore apply compost amendments within the Phase III pond,
in the wetted, emergent and riparian areas prior to the native planting treatment. The
compost used will consist of compost bark, river sand, mushroom manure and native soil
supplied by Super Soil Inc. (Surrey, BC).
Growing plants uptake nitrogen throughout the growing season and can absorb any form of
soluble nitrogen (Vymazal and Kröpfelová 2008). A study by Bachand and Horne (1999)
assessed which common wetland plants (i.e. Bulrush (Scirpus sp.), Cattail (Typha sp.),
Juncus sp., Carex sp. and grasses) create optimal conditions for denitrification in restored
wetlands. The study found a mixed treatment of the common wetland plants removed
three times more nitrate than the bulrush treatment. We will therefore use a mixture of
emergent and riparian plants to improve denitrification rates in the constructed wetland
and existing pond on the Phase III site (see Section 7.5. Installing Native Vegetation).
Finally, we will consult with an engineer experienced in designing constructed wetlands for
treatment of agricultural water, for further guidance prior to and during the construction of
the wetland on the Phase III site.
7.3.5. Freshwater Fish Habitat Requirements
After examination of the seasonal hydrology of the pond, we will implement changes in the
depth of the pond to ensure it remains permanently wetted during summer low flows. This
is to create critical habitat required by the Salish Sucker, Coho Salmon, and Coastal
Cutthroat Trout. A limiting factor for Coho smolt production during summer months is the
availability of pools in this region (Nickelson et al. 1992). Additionally, permanent pools
that remain during summer low flow provide critical refuge habitat for Coastal Cutthroat
Trout (Rosenfeld et al. 2000). Salish Sucker fish are generally found in long (> 50 m)
connected pools with depths exceeding 70 cm (DFO 2015). These areas are characteristic
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of wetland headwaters, where high densities of Salish Sucker occur (COSEWIC 2012).
During winter, juvenile Coho Salmon density increases in dammed pool habitat such as
beaver ponds. Beaver dams create ideal habitat by backing up water and creating long deep
pools with slow moving water (Pearson and Healey 2003).
We will create the habitat features required by the target fish species by expanding,
regrading and increasing the depth of the pond (if needed) to maintain summer water
levels. We will either maintain or increase the current pond depth, depending on the lowest
water level recorded in the pond during the dry summer months. We want to ensure the
pond can accommodate the above-mentioned fish species by ensuring it remains
permanently wetted throughout the year at a depth larger than 70 cm.
By maintaining a permanently wetted pond during the summer, we are also increasing
availability of these essential summer refuge habitats for the salmonid species. Riparian
plantings will help maintain these temperatures by increasing shaded areas surrounding
the pond during summer months (see Section 7.5. Installing Native Vegetation). For Coho
Salmon and Salish Sucker fish species water temperatures must remain between 6 and 21
°C (RTSS 2010, Brett 1952, Levy and Slaney 1993).
7.3.6. Grade Control Structure
The outflow from the pond into the drainage ditch will have to be controlled due to
infrastructure and farming fields located downstream. We will install a basic grade control
structure at the pond outflow, following the same design as those used in the Phase I site
wetland (Fig. 6). The outflow area of the pond will be will be bermed (with the spoils from
the wetland and pond excavation) to retain water. It will then be fitted with a spillway to
ensure that flooding of the upland areas of the pond does not occur during high rainfall
events. This will also be a point of entry for Coho Salmon and Coastal Cutthroat Trout
seeking refuge from high winter flows or low summer flows in the drainage ditch. An L-
shaped PVC pipe will run through the spillway and act as a grade control structure. When
the water level is high enough, it will breach the top of the L-shaped PVC and flow to the
downstream side of the spillway. The grade control structure will function to maintain a
maximum level of water in the pond during seasonal wet periods.
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Figure 7. Visualization of grade control structure that will be installed at the lower end of the
expanded pond on the Phase III site. It will connect the pond to the drainage ditch along 0 Avenue.
7.4. Pond Construction
Pond regrading and expansion will occur concurrently with wetland expansion in the
southwest corner of the site (see Section 7.2. Wetland Expansion Treatments). Prior to
construction remaining water from the pond will be drained into the drainage ditch along 0
Avenue. This is only necessary is the water level is too high, making the area unsuitable for
the use of an excavator. We will delineate the expected wetted area, by marking the lobed
areas of the pond to be excavated. The willows surrounding the pond within the marked
wetted area will be removed with the excavator and then added to the pond periphery
following construction. We will use a level in this area to record elevations of the pond
during construction to ensure accurate bank slopes and pond depth is achieved. The
excavator will begin by forming a berm with a spillway at the pond outflow point, then
continue to expand and deepen the pond and regrade the banks to the desired grade.
Following construction wildlife features for Salish Sucker, Coho Salmon and Coastal
Cutthroat Trout will be added. This includes gravel, LWD and emergent vegetation (see
