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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. King County began collecting benthic macroinvertebrate samples in Pine Lake Creek in 2002.

Watershed

Water Shed Image 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).

Fisheries

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 now categorized as “Core Summer Salmonid Habitat” for aquatic life use, and “Extraordinary Contact” for recreational use. The creek is on the 2012 Washington Department of Ecology’s (Ecology) 303(d) list for violation of dissolved oxygen and fecal coliform bacteria standards (Category 5). See Table 1 for a summary of water quality violations in the creek during the most recent water year.

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. To see how these ratings compare with other stream sites, visit the Water Quality Index page.

Table 1. Routine monitoring summary statistics for this station from 1987 to 2017
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)25610.57.714.210.41.3
Temperature (°C)2969.71.116.69.93.5
Turbidity (NTU)2632.810.5039.101.923.66
pH2847.366.277.807.400.25
Conductivity (mSIEMS/cm)233138.464.0201.0144.044.8
Total Suspended Solids (mg/L)2986.350.50131.002.8513.09
Ortho-Phosphorus (mg/L)2980.04400.01240.09110.04290.0162
Total Phosphorus (mg/L)2980.07180.02150.33900.06800.0326
Ammonia (mg/L)2980.01880.00520.08220.01510.0111
Nitrate (mg/L)2980.37830.09101.68000.33650.2065
Total Nitrogen (mg/L)2860.74820.27902.38000.70950.3474
Fecal Coliform(CFU/100ML)2971431380045346

Table 2. Storm water monitoring summary statistics for this station from 1987 to 2017
ParameterNumber of SamplesMeanMinimumMaxmiumMedianStandard Deviation
Dissolved Oxygen (mg/L)4510.37.412.910.01.4
Temperature (°C)569.92.815.010.02.8
Turbidity (NTU)4824.121.60400.005.2564.65
pH557.266.367.807.300.27
Conductivity (mSIEMS/cm)40117.552.0191.0109.046.6
Total Suspended Solids (mg/L)5663.640.601740.0011.00238.07
Ortho-Phosphorus (mg/L)560.04800.02280.09360.04500.0175
Total Phosphorus (mg/L)560.13890.04531.61000.09720.2142
Ammonia (mg/L)560.02280.00700.11400.01600.0183
Nitrate (mg/L)560.61640.13301.95000.45900.4540
Total Nitrogen (mg/L)561.22220.42204.46001.02000.7484
Fecal Coliform(CFU/100ML)5645082700285533

Hydrology

King County operates a stream gage on Pine Lake Creek near its mouth at the Sammamish River Parkway 15b.

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

Benthic macroinvertebrates are small animals visible to the naked eye (macro) that lack a backbone (invertebrate) and live in or around the streambed (benthic). This group includes aquatic insects (such as mayflies and dragonflies), crustaceans, clams, snails, and worms. Benthic macroinvertebrates are of interest to scientists and water resource managers because they are an excellent indicator of the biological health of stream ecosystems and are a critical component of the food web in aquatic communities. Scientists quantify the composition and diversity of benthic macroinvertebrate populations in a stream to compare the biologic integrity of different streams. King County has utilized benthic macroinvertebrate sampling to assess biological health of numerous creeks across the county (see map).

For more information about benthic macroinvertebrates and King County’s Benthic Macroinvertebrate Program, please visit the King County Stream Bug Monitoring web page. To see the benthic macroinvertebrate data for Pine Lake Creek, please visit the Puget Sound Benthos webpage.

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.