USGS Washington Water Science Center
|Project Summaries | Publications and Products | Partnerships ||
WA222 - General Hydrology and External Nutrient Sources of Pine Lake, King County - Completed FY1983
Problem - Pine Lake is an eutrophic lake that frequently develops late spring and summer blooms of blue-green algae. Other indications of its advanced trophic state include dense growths of macrophytes, high turbidity, high nutrient concentrations in winter and early spring, and an anaerobic hypolimnion during summer thermal stratification. For these reasons, the lake is a candidate for water-quality restoration. Before the most efficient restoration technique can be selected, however, the seasonal nutrient concentrations responsible for the enriched state of the lake and the sources of these nutrients need to be known. In addition, little is known of the hydrologic (especially ground-water) conditions in the immediate vicinity of the lake--conditions which most likely influence transport of nutrients.
Objectives - The objectives of the proposed study would be to determine (1) the environmental features of Pine Lake, (2) the general hydrologic conditions in the immediate vicinity of the lake, and (3) the most likely external sources of nutrients that affect the lake.
Approach - Published reports will be used to determine physical, chemical, and biological aspects of Pine Lake. The general hydrologic conditions in the vicinity will be determined by conducting a well inventory and installing 15-20 additional shallow wells. A nest of piezometers will be installed in a deep well and precipitation station will be installed on the lake. Continuous-recording discharge gages will be established on inlet and outlet streams and a water budget prepared. Existing and newly installed wells will be sampled 2 times per year and precipitation samples collected 4 times per year to determine nutrient concentrations. A map of cultural and land-use patterns in the drainage area of the lake will be prepared. Using these data, the magnitude and significance of the nutrient loads carried to the lake by various means will be estimated.