Abstract

Identifying Monitoring Locations to Study Toxic Runoff to Puget Sound
Track: Water Resources
Authors: Jennifer Schmidt, GISP

Washington State Department of Ecology (Ecology) is collaborating with state and federal agencies to study toxic chemicals discharging to Puget Sound in surface runoff. As part of Phase 3, Herrera used GIS to help select 16 representative on-the-ground watersheds for collecting water quality sampling and flow monitoring data in two Water Resource Inventory Areas (WRIAs). Selection criteria included stream order, elevation, dominant land use, and site accessibility.

This presentation will focus on the DEM-based approach that Herrera developed using Spatial Analyst and Python to delineate and analyze more than 800 subbasins and identify those meeting monitoring criteria for a 3,000 square-mile study area. Results were randomly field-verified for monitoring feasibility and used to successfully identify 12 of 16 final locations. Monitoring data were used to compute unit area loads for toxic chemicals by land type. Results are being used to guide decisions on effectively resolving contamination issues in Puget Sound.