Publication Summary

This is the study plan for the Des Moines, Massey, and McSorley Creeks Copper and Zinc Water Quality Assessment.

A five-year study conducted for the city of Des Moines (1995-1999) reported that Des Moines Creek, Massey Creek, and McSorley Creek violated water quality criteria for dissolved copper and zinc (copper only for McSorley) during storm events. These data led to the listing of the 3 streams under Section 303(d) of the federal Clean Water Act as water quality impaired. Because the data are more than five years old and many changes in stormwater management have occurred within these watersheds, updated information is required to verify the need for a Total Maximum Daily Load (water cleanup plan) analysis.

The Washington State Department of Ecology (Ecology) will conduct a water quality study in Des Moines, Massey, and McSorley Creeks to determine existing conditions. Levels of copper and zinc during both baseflow and storm events will be determined. If study data indicate levels higher than the water quality standards, the needed reductions in existing copper and zinc loads from potential sources will be determined.

Each study conducted by Ecology must have an approved Quality Assurance Project Plan. The plan describes the objectives of the study and the procedures to be followed to achieve those objectives. After completion of the study, a final report describing the study results will be posted to the Internet.

Link to EIM data for User Study ID RCOO0009