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, 20 th 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

• Land use data source:  Monterey County Tax Assessor’s Office and City of Pacific Grove.• Impervious cover data source: USGS, NLCD 2006

Impervious Cover

Watershed Characteristics

Watershed ID

Multi-Family Residential (%)

Publicly Owned (%)

Recreation (%)

Vacant (%)

Community Center (%)

Single Family Residential (%)

Industrial (%)

Parking Lots (%)

Auto Services (%)

Commercial (%)

Medical (%)

Restaurants (%)

1 11.3 6.7 0.0 2.7 3.8 33.8 0.0 5.6 4.8 22.5 0.2 7.32 49.5 0.0 0.0 0.0 0.9 38.3 0.0 0.0 0.0 0.0 9.3 0.03 34.5 0.0 0.0 0.0 0.0 58.6 0.0 0.0 0.0 0.0 0.0 0.04 57.9 0.0 0.0 0.0 0.0 42.1 0.0 0.0 0.0 0.0 0.0 0.05 29.6 3.0 0.0 1.0 4.0 59.3 0.0 0.0 0.0 0.0 0.0 0.06 16.9 0.0 0.0 2.4 3.9 75.8 0.0 0.0 0.0 0.0 0.0 0.07 31.2 3.0 0.0 0.0 15.6 43.6 0.0 0.0 0.0 0.0 3.7 0.08 10.5 13.5 6.0 1.5 4.5 60.2 0.3 0.3 0.1 1.5 1.1 0.29 28.1 0.0 0.0 0.0 21.9 50.0 0.0 0.0 0.0 0.0 0.0 0.010 11.4 25.0 0.0 0.0 0.0 20.5 0.0 0.0 0.0 43.2 0.0 0.011 66.7 0.0 0.0 0.0 0.0 33.3 0.0 0.0 0.0 0.0 0.0 0.012 22.8 23.8 0.0 1.0 0.0 29.7 0.0 0.0 0.0 22.8 0.0 0.013 9.6 4.8 0.0 0.5 0.7 76.9 0.0 0.5 0.3 1.6 4.8 0.214 22.4 77.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.015 81.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 18.616 61.0 2.4 0.0 0.0 0.0 36.6 0.0 0.0 0.0 0.0 0.0 0.017 78.8 12.1 0.0 0.0 0.0 9.1 0.0 0.0 0.0 0.0 0.0 0.018 78.3 15.2 0.0 0.0 0.0 6.5 0.0 0.0 0.0 0.0 0.0 0.019 12.5 12.5 0.0 0.0 0.0 75.0 0.0 0.0 0.0 0.0 0.0 0.020 61.5 30.8 0.0 0.0 0.0 7.7 0.0 0.0 0.0 0.0 0.0 0.021 13.2 33.0 0.0 1.1 0.0 52.7 0.0 0.0 0.0 0.0 0.0 0.022 0.0 0.0 0.0 13.3 0.0 86.7 0.0 0.0 0.0 0.0 0.0 0.023 5.2 26.0 0.0 1.1 0.0 67.6 0.0 0.0 0.0 0.0 0.0 0.024 0.0 1.7 0.0 0.0 0.0 98.3 0.0 0.0 0.0 0.0 0.0 0.025 7.6 87.6 0.0 0.8 0.0 3.8 0.0 0.0 0.0 0.0 0.0 0.026 0.0 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.027 0.0 1.3 0.0 21.6 0.0 77.1 0.0 0.0 0.0 0.0 0.0 0.028 41.0 5.9 0.0 5.9 0.0 46.8 0.0 0.0 0.0 0.0 0.0 0.029 0.0 0.0 0.0 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.0 0.030 12.1 4.3 0.0 9.9 0.0 72.7 0.0 0.6 0.0 0.0 0.0 0.031 8.6 17.1 0.0 1.7 0.4 72.0 0.0 0.0 0.0 0.0 0.0 0.032 0.0 40.3 0.0 0.0 0.0 59.7 0.0 0.0 0.0 0.0 0.0 0.033 0.0 89.6 0.0 0.0 0.0 10.4 0.0 0.0 0.0 0.0 0.0 0.034 0.0 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Potential MitigationTreatment Wetlands

Stormwater inflow

Stormwater outflow

Treatment Wetland

Detention Pond

Basic Schematic of Wetland SystemWatershed #8, Greenwood Park

Potential MitigationBioretention

Image courtesy of Ole Christensen

Potential MitigationGreen concrete alternatives

GCA 4-8”

Natural Substrate

Aggregate Base 1 (1-2”)

Aggregate Base 2 (+6”)

Surface Runoff Interception

Direct Rainfall Interception

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?