Stormwater outfall watershed
delineation, land cover
characteristics, and recommended
priorities for monitoring and
mitigation in the City of Pacific
Grove, California
Kathy Pugh
Roger Arenas
Patty Cubanski
Michele Lanctot
AJ Purdy
Ryan Bassett
Jacob Smith
Shaelyn Hession
Kyle Stoner
Gabriela Alberola
Natalie Jacuzzi
Rose Ashbach
Fred Watson
Presentation by CSUMB class ENVS 660 to stormwater management staff from City of Pacific Grove, City of Monterey,
Monterey Regional Storm Water Management Program, and Monterey Bay National Marine Sanctuary, 20th Sep 2011.
Field Methods
• Located outfalls 10” diameter and greater
• Coordinates & measurements recorded
• Photographed
• Field validated GIS delineated watersheds
Delineation Methods
• Imported storm drain mains data
and Digital Elevation Model
• Reclassified storm drain raster to be binary
• Subtracted reclassified storm drain raster from the DEM
to create “burned” DEM.
• Imported storm drain outfall location data
• Hydrology Tools within Spatial Analyst
• Fill analysis
• Directional analysis
• Accumulation analysis
• Edited outfalls
• Watershed analysis
Watershed Boundaries
Land Use
Impervious Cover
• Land use data source: Monterey County Tax Assessor’s Office and City of Pacific Grove.
• Impervious cover data source: USGS, NLCD 2006
Watershed
Characteristics
Watershed
ID
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Multi-Family
Residential (%)
11.3
49.5
34.5
57.9
29.6
16.9
31.2
10.5
28.1
11.4
66.7
22.8
9.6
22.4
81.4
61.0
78.8
78.3
12.5
61.5
13.2
0.0
5.2
0.0
7.6
0.0
0.0
41.0
0.0
12.1
Publicly
Owned (%)
6.7
0.0
0.0
0.0
3.0
0.0
3.0
13.5
0.0
25.0
0.0
23.8
4.8
77.6
0.0
2.4
12.1
15.2
12.5
30.8
33.0
0.0
26.0
1.7
87.6
100.0
1.3
5.9
0.0
4.3
Recreation
(%)
0.0
0.0
0.0
0.0
0.0
0.0
0.0
6.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Vacant
(%)
2.7
0.0
0.0
0.0
1.0
2.4
0.0
1.5
0.0
0.0
0.0
1.0
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.1
13.3
1.1
0.0
0.8
0.0
21.6
5.9
0.0
9.9
Community
Center (%)
3.8
0.9
0.0
0.0
4.0
3.9
15.6
4.5
21.9
0.0
0.0
0.0
0.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Single Family
Residential (%)
33.8
38.3
58.6
42.1
59.3
75.8
43.6
60.2
50.0
20.5
33.3
29.7
76.9
0.0
0.0
36.6
9.1
6.5
75.0
7.7
52.7
86.7
67.6
98.3
3.8
0.0
77.1
46.8
100.0
72.7
Industrial Parking Auto Services Commercial
(%)
Lots (%)
(%)
(%)
0.0
5.6
4.8
22.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.3
0.1
1.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
43.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
22.8
0.0
0.5
0.3
1.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.6
0.0
0.0
Medical Restaurants
(%)
(%)
0.2
7.3
9.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
3.7
0.0
1.1
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4.8
0.2
0.0
0.0
0.0
18.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Potential Mitigation
Treatment Wetlands
Stormwater
outflow
Stormwater
inflow
Watershed #8, Greenwood Park
Basic Schematic of Wetland System
Potential Mitigation
Bioretention
Image courtesy of Ole Christensen
Potential Mitigation
Green concrete alternatives
Direct Rainfall Interception
Surface Runoff Interception
Aggregate Base
1 (1-2”)
Aggregate
Base 2 (+6”)
GCA 4-8”
Natural
Substrate
Next steps
• Prioritize delineated watersheds according to mitigation needs
• Collect data necessary for hydrologic modeling
• Precipitation
• local, high-resolution
• Outfall discharge
• Key outfalls
• Soil Characteristics
• Field verification
• Continued water quality monitoring
• Build and calibrate watershed model
• Greenwood Park given priority
• Assess mitigation measures feasibility using model simulations
• Restructure and reassess mitigation designs if needed
• Implement mitigation measures
• Continue monitoring
Conclusions/ Questions?