USGS Washington Water Science Center
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WA290 - Background Water Quality of Goat Lake Watershed, Snohomish County - Completed FY1993
Problem - In 1982, the Goat Lake watershed was selected by the USGS as an "experimental watershed" to function as the focus for long-term studies on the effects of acidic precipitation on water resources. The reasons for selecting Goat Lake were as follows: (1) the lake contains dilute water and is highly sensitive to acidic inputs from atmospheric deposition and streamflow; (2) during the rainy (winter) season, the lake is downwind of the Tacoma-Seattle-Everett industrial and urban area that emits sulfurous and nitrous oxides that combine with atmospheric moisture to produce acidic precipitation; (3) the lake is situated at high altitude and receives more than 150 inches of precipitation per year; (4) the lake is in a wilderness area, where land-use changes are unlikely; (5) the lake is relatively inaccessible and is unlikely to be substantially affected by man; and (6) the lake is typical of numerous lakes in the Cascade Range.
Objectives - The objective of the ongoing data-collection project at Goat Lake is to collect sufficient discharge and water-quality data for the inflow and outflow to enable a general assessment of the water-quality characteristics of the streams, especially with respect to those constituents that are sensitive to, or indicative of, acidic precipitation.
Approach - Samples from the outflow and principal inflow will be collected monthly. Specific conductance and pH will be measured in the field. The samples will then be processed and prepared for Central Laboratory analysis for calcium, magnesium, sodium, potassium, chloride, sulfate, nitrate, phosphate, fluoride, alkalinity, pH, specific conductance, iron, manganese, and aluminum. Samples for the determination of iron, manganese, and aluminum will be filtered through a .10-micron filter and acidified with ultra-pure nitric acid. A non-recording gage that monitors precipitation quantity will be maintained just downstream of the lake outlet.