Pine Lake Creek Site A680

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King County Water Quality Monitoring

King County monitors the ecological health of Pine Lake Creek in a variety of ways including collecting and analyzing water, sediment, and benthic invertebrate samples. Since 1987 water quality samples have been collected monthly near the mouth of the creek at Station A680, located downstream of the railroad tracks between East Lake Sammamish Parkway and the East Lake Sammamish bike trail. Sediment samples have been collected from Pine Lake Creek as part of the Streams Sediment Monitoring Program starting in 1987. In 2002 and 2003 benthic invertebrates were sampled from Pine Lake Creek.p>

Pine Lake Creek Watershed

The Pine Lake Creek subbasin is located within the City of Sammamish and drains 1,175 acres from the East Lake Sammamish Subbasin into the lake along the eastern shoreline. Pine Lake Park, a 16 acre park, is an important recreational and aesthetic resource to the City of Sammamish.

The 1994 East Lake Sammamish Basin Plan identified Pine Lake Creek as providing habitat for anadromous fish use up to River Mile 0.6 and resident fish use above that. Good spawning substrate was found in the lower section of the creek. Pine Lake provides valuable fish and wildlife habitat for many species. In 1988 drainage from a large wetland was diverted from Pine Lake into Pine Lake Creek to reduce nutrient loading to the lake (King County 1994).

Water Quality

Water quality samples are analyzed monthly for temperature, dissolved oxygen (DO), pH, conductivity, turbidity, total suspended solids, ortho-phosphorus, total phosphorus, ammonia, nitrate-nitrogen, total nitrogen, and fecal coliform bacteria (FC). Results are compared to State water quality standards. Water quality standards are designed to protect public health and aquatic life. Comparing monitoring results to water quality standards allows an understanding of how safe the creek is for recreational contact as well as for aquatic life. (See link at top of page to view current water data.)

State water quality standards were revised in 2003. Pine Lake Creek is considered a Class AA water body under the 1997 rules. As the 2003 become effective the creek is categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Primary Contact” for recreational use. The creek is on the 2004 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen and fecal coliform bacteria standards.

Pine Lake Creek has historically had water quality concerns due to high fecal coliform bacteria levels and phosphorus concentrations (King County 1994).

Water Quality Index

A Water Quality Index (WQI) rating system was developed by the State Department of Ecology that evaluates several water quality parameters and gives a single rating of “high,” “moderate,” or “low” water quality concern. During the last six water years water quality in Pine Lake Creek was rated of “moderate concern”, with the exception of a “high concern” rating in 2004-05. The “high concern” was due primarily to high fecal coliform bacteria and high nutrient concentrations. To see how these ratings compare with other stream sites, visit the Water Quality Index page.

A review of the water year 2007 data shows the following violations of State water quality standards:

 

Stream Sediment

Sediment data were collected from Pine Lake Creek as part of the Streams Monitoring program starting in 1987. Data were compiled and analyzed for the years 1987 through 2002. Data were analyzed for trends, correlations, and were compared to sediment quality guidelines. No significant trends were identified during data analysis for any of the parameters tested. Results indicate that Pine Lake Creek sediments did not exceed any sediment quality guidelines. Of the 27 steams monitored in King County, Pine Lake Creek had the 11th lowest metals concentrations.

Benthic Invertebrates

In both 2002 and 2003, benthic invertebrate samples were collected, analyzed, and benthic invertebrate index scores (BIBI) were calculated for Pine Lake Creek as part of the King County's Benthic Macroinvertebrate Program. Benthic invertebrates are an important link in the food chain for fish in the creek and are an excellent indicator of stream health.

BIBI scores from both years indicate that conditions in Pine Lake Creek were poor for benthic invertebrates. For both years a wide range of between about 33 and 72 percent of the species present were tolerant of degraded conditions. It is unclear why the difference between the two years was so great. It will be of interest to monitor this creek in the future to determine if there is a trend or if the difference is explained by some other phenomena such as sampling variability. During both years, very few individuals of species that are long-lived or sensitive to degraded conditions were present. Longer-lived species tend to take longer to reproduce and, along with sensitive species, are among the first to disappear when a stream ecosystem is altered by human activity such as urbanization.p>

Special Studies

Water Resources Inventory Area (WRIA) 8

In WRIA 8, citizens, scientists, businesses, environmentalists and governments are cooperating on protection and restoration projects and have developed a science-based plan to conserve salmon for future generations. Visit the WRIA 8 page to see how Pine Lake Creek is part of this WRIA 8 planning process.