1.
Watershed Assessment Modeling to
Identify Critical Sources of Pollution and
Evaluate Effectiveness of Conservation
Management Practices
Nichole Embertson, Ph.D.
Science and Planning Coordinator
Whatcom Conservation District
SWCS Conference | July 31, 2018

2.
Tenmile Watershed was selected for
2017 NWQI Pilot Project
NWQI Goal:
Implement voluntary conservation
practices to improve water quality in
high-priority watersheds while
maintaining agricultural productivity.

3.
 Contained 35.4 mi2
watershed with diverse land
uses
 WCD actively working with
landowners in watershed
 NRCS technical and
financial assistance available
 Existing stakeholder and
landowner engagement
 Water quality monitoring
and specific water quality
targets (TMDL)
 Current focus on improving
water quality in watershed
Why Tenmile Watershed?

4.
Phosphorus Nitrogen
Suspended
Solids
Pathogens
Watershed Assessment
Identify Water Quality Concerns

5.
Watershed Characterization
Land use survey: Agricultural Land Use

6.
OpenNSPECT* Model Assessment
What goes in?
Topography
Soils
Land use
Precipitation
*OpenNSPECT = Open-source Nonpoint Source Pollution and Erosion Comparison Tool

7.
OpenNSPECT* Model Assessment
What comes out?
Phosphorus
Suspended
Solids
Nitrogen
Pathogens
Darker color = higher potential source contribution
We call these critical source areas.
*OpenNSPECT = Open-source Nonpoint Source Pollution and Erosion Comparison Tool

8.
Model Outcome: Combined ranking based on
all four water quality concerns
Green = low potential source contribution
Yellow = moderate
Red = highest potential source contribution

9.
Fewer dark areas = fewer potential source locations
Evaluate Effectiveness of Ag BMPs
Example: Implementation of Cover Crops on Fallow Fields
Phosphorus Nitrogen
No Cover
Cover
Crops
With
Cover
Crops

10.
What Can We Do With Modeling
Results?
 Focus planning efforts in critical source areas or
specific land uses
 Evaluate the effectiveness of various BMPs by land
use type and practice
 Determine the impact and potential effectiveness of
NRCS programs in an area
 Focus cost-share priorities and funding
 Adapt outreach materials and efforts to meet the
social considerations of landowners in a watershed

11.
Social Factors and Outreach
Effective management of water pollution must
address both:
Environmental conditions
and
Choices people make that impact the environment
Focus
Groups
Land Owner
Survey
Outreach
Plan
Community
Engagement

12.
Greatest Threats to Water Quality
Percent of respondents
Outreach Survey: Greatest Threats to Water Quality

13.
Percent of respondents
Outreach Survey: Barriers to Implementation

14.
34
33
32
31
31
31
28
27
21
21
16
16
15
13
10
7
2
7
0 10 20 30 40
Department of Health
Whatcom Family Farmers
Whatcom Conservation District
Laurel Watershed Improvement District
Tenmile Clean Water Project
WSU University Extension
Whatcom Farm Bureau
Other local landowners, friends, etc.
WA State Department of Agriculture (WSDA)
WA State Department of Ecology
Farm Service Agency
Natural Resources Conservation Service…
A local farm and garden center
Local livestock group
U.S. Environmental Protection Agency (EPA )
Whatcom County
Fertilizer or seed sales people
Some other agency or organization
Percent of Respondants
All respondents (n=177)
Outreach Survey: Trusted Sources of Information

15.
Overall Outcomes of Tenmile
Watershed Assessment
 Characterization of Tenmile Watershed
 Identify high risk land uses and effective conservation practices
 Understand social factors affecting BMP implementation and
how to address specific to watershed
 Outreach to landowners is now targeted based on watershed,
impact modeling and community
 Better, strategic allocation of resources (time, $) and efforts
informed by the watershed assessment
 Expect water quality improvements long-term
 Expand to other watersheds for better planning, outreach, and
implementation

16.
Report Contents:
A. Background and Purpose
B. Watershed Characterization
C. Hydrologic and Water
Quality Characterization
D. Resource Analysis
Assessment
E. Summary and
Recommendations
F. Outreach
G. References
H. Appendix
I. Local Contacts
www.whatcomcd.org/tenmile

17.
Disclaimer: The reproduction or use of any of the images or content within
this document is not allowed without prior approval from the creator.
Nichole M. Embertson, Ph.D.
Science and Planning Coordinator
Whatcom Conservation District
O: (360) 526-2381 x 126
E: nembertson@whatcomcd.org
www.whatcomcd.org/tenmile
Thanks Project Team!
Megan Harris
Aneka Sweeney
Andrew Phay
WCD and NRCS Staff
Questions?