Thurston County Water Resources Monitoring Report 2019 Water Year Report Includes: Water Quality of Lakes • Black Lake • Deep Lake • Hicks Lake • Lawrence Lake • Long Lake • Offutt Lake - 2018 & 2019 • Summit Lake December 2020 • Ward Lake Prepared by: Thurston County Public Health and Social Services Department, Environmental Health Division and Thurston County Community Planning and Economic Development, Stormwater Utility In Cooperation With: City of Olympia Public Works, Water Resources Program City of Lacey Public Works, Water Resources Program City of Tumwater Public Works Department 2019 Black Lake Water Quality Report Prepared by Thurston County Environmental Health Division Figure 1. Black Lake map showing location of sample site BL2. PART OF BUDD INLET WATERSHED which has a swim area. Also, Black Lake can be accessed at two private resorts, one church • SHORELINE LENGTH: 6 miles camp, and several private community areas. • LAKE SIZE: 0.9 square miles (570 acres) • BASIN SIZE: 10.1 square miles GENERAL TOPOGRAPHY: • MEAN DEPTH: 19 feet (5.8 meters) The approximate altitude of the lake is 130 feet • MAXIMUM DEPTH: 29 feet (8.8 meters) above mean sea level. The terrain to the east • VOLUME: 11,000 acre-feet of the lake is very flat. Two tributaries originate in wetlands on the east side of the lake. On the PRIMARY LAND USES: west side, there is one year-round stream and A large percentage of the lake shore is several intermittent streams that flow into the moderate-density residential. There are two lake. The lake outlet is through a ditch at the large mobile home parks on the east shoreline north end of the lake, which flows to Percival and two RV commercial resorts on the west Creek. Periodically, beaver dam the outlet side of the lake. The south and north ends are ditch. The historic outlet was to the south via dominated by extensive wetland systems the Black River, which is now obstructed by (Figure 1). numerous beaver dams and vegetation. PRIMARY LAKE USE: GENERAL WATER QUALITY: Black Lake is used for domestic water supply, Fair – Black Lake is eutrophic. In 2019, the fishing, boating, swimming, and other water mean Total Phosphorus (TP) concentration was sports. above the action level. Productivity was high and transparency was lower than average. The PUBLIC ACCESS: TP concentration has declined since 2016, The Washington Department of Fish and when the Black Lake Special District applied Wildlife operates one public boat launch. alum. Samples for algal toxins have not been Thurston County manages Kennydell Park, above the Washington State advisory levels since 2015. Black Lake 2019 DESCRIPTION Black Lake, one of the largest lakes in Thurston County, is located west of Tumwater, Washington. Several small creeks flow into Black Lake. Extensive wetlands, especially along the north and south shores, are fed by the shallow groundwater system. These wetlands influence the water quality characteristics of the lake. Historically, the lake outlet flowed south to the Black River. In 1922, Black Lake Ditch was excavated in order to drain agricultural land north of Black Lake, linking Black Lake to Percival Creek. Black Lake has three boat ramps and is popular for recreation. The Department of Fish and Wildlife stocks rainbow trout in the fall and spring. Black Lake supports natural populations of cutthroat trout, largemouth and smallmouth bass, yellow perch, black crappie, and brown bullhead catfish. High levels of Total Phosphorus (TP) caused Black Lake to be placed on the 303(d) list in 1996 and 1998. It has been listed as Category 5 for TP since 2004. Black Lake is currently listed as Category 2 for mercury in fish tissue based on samples largemouth bass in 2002 and rainbow trout in 2004. The Black Lake Special District raises funds to protect and enhance water quality and lake habitat. Alum was applied in 2016, which reduced TP at the surface and bottom of the lake and reduced toxic algae blooms. METHODS In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Black Lake from May to October. Figure 1 shows the sample site BL2 , located in the deepest part of the lake. Table 1 lists the types of data collected (TCEH, 2009) and Appendix A provides the raw data. The Custer Color Strip (Figure 2) has been used as a reference for water color since the 1990s. Table 1. List of parameters, units, method, and sampling locations. Parameter Units Method Sampling Location Transparency meters Secchi Disk Depth where disk is no longer visible Color #1 to #11 Custer Color Strip Color of water on white portion of Secchi Disk • Water Temperature (°C) Vertical Water • Dissolved Oxygen (mg/L) YSI EXO1 Multi- ~ 0.5 meter below the water surface to Quality Profile • pH (standard units) parameter Sonde ~ 0.5 meter above the bottom sediments • Specific Conductivity (µS/cm) Total Grab Samples with Surface Sample: ~ 0.5 meter below the surface mg/L Phosphorus Kemmerer Bottom Sample: ~ 0.5 meter above the benthos Grab Samples with Surface Sample: ~ 0.5 meter below the surface Total Nitrogen mg/L Kemmerer Bottom Sample: ~ 0.5 meter above the benthos Composite of Multiple Chlorophyll-a µg/L Photic Zone Grab Samples Composite of Multiple Phaeophytin-a µg/L Photic Zone Grab Samples 2 Black Lake 2019 Figure 2. TCEH compared water color to the Custer Color Strip. Quality Assurance and Quality Control (QA/QC) TCEH collected 10% field replicates and daily trip blanks to assess total variation (3 to 4 lakes sampled each day). The calibration of the Yellow Springs Instrument (YSI) EXO1 was verified before and after each sampling day. See Appendix B for QA/QC data. RESULTS Weather Conditions Weather conditions during the 2019 sample season are provided in Table 2. Table 2. Weather on sample days and the average, minimum, and maximum air temperatures for each month from Olympia Regional Weather Station. Monthly Weather Month Weather on Sample Day Temperature (°C) Mean (Low/High) May Mostly cloudy (16°C); 0-5 mph NW wind 13 (2/30) June Fair (23°C); 0-3 mph var wind 15 (4/33) July Cloudy, (21°C); 0-7 mph W wind 18 (8/32) August Fair (26°C); 0-10 mph ENE wind 18 (7/33) September Light rain (16°C); 0-3 mph SSW wind 14 (-1/26) October Light rain (12°C); 15-21 mph SSW wind 8 (-6/18) Vertical Water Quality Profiles During the summer, lakes often stratify into layers based on temperature and density differences. • Epilimnion: upper warm, circulating strata in contact with the atmosphere • Metalimnion: middle layer with steep thermal gradient (thermocline) • Hypolimnion: deepest layer of colder, relatively stagnant water The vertical water quality profiles illustrate how the water column at Black Lake changed over the sample season. Black Lake was thermally stratified from June to August 2019 (Figures 3 to 4), when warmer, more oxygenated water existed on the surface in the epilimnion. Below this layer, the 3 Black Lake 2019 temperature and oxygen concentration declined with depth. Figure 5 demonstrates how Black Lake turned over in September 2019. Black Lake - May 21, 2019 Black Lake - June 17, 2019 Temperature (°C), pH (std), DO (mg.L) Temperature (°C), pH (std) , DO (mg/L) 0 5 10 15 20 25 0 5 10 15 20 25 0 0 1 1 2 2 3 3 4 4 5 5 Depth (meters) Depth (meters) 6 6 7 7 8 8 0 20 40 60 80 100 120 0 20 40 60 80 100 120 SPC (µS/cm) SPC µS/cm TEMP pH D.O. SPC TEMP pH D.O. SPC Figure 3. Vertical water quality profiles for Black Lake at BL2 collected in May and June 2019. In May and June, the lake was beginning to stratify; DO and pH declined and SPC increased below five meters depth. • May Epilimnion – Temperature 17.1°C; DO 9.5 mg/L; pH 7.9 • May Hypolimnion – Temperature 12.6°C; DO 0.71 mg/L; pH 6.9 • June Epilimnion – Mean Temperature 22.3°C; Mean DO 9.7 mg/L; pH 8.2 • June Hypolimnion – Mean Temperature 15.3°C; Mean DO 0.5 mg/L; pH 6.6 The epilimnion had much higher DO because this layer gained oxygen from the atmosphere and photosynthesis. Oxygen consuming processes or advection of low oxygen groundwater produced anoxic conditions in the hypolimnion. A clinograde curve DO curve was developing in May and June. 4 Black Lake 2019 Black Lake - July 23, 2019 Black Lake - August 26, 2019 Temperature (°C), pH (std), DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 25 0 5 10 15 20 25 0 0 1 1 2 2 3 3 4 4 5 Depth (meters) Depth (meters) 5 6 6 7 7 8 0 20 40 60 80 100 120 140 160 180 0 20 40 60 80 100 120 140 160 180 SPC (µS/cm) SPC (µS/cm) TEMP pH D.O. SPC TEMP pH D.O. SPC Figure 4. Vertical water quality profiles for BL2 at Black Lake collected in July and August 2019. The temperature of the epilimnion reached the summer peak in July. • July Epilimnion – Mean Temperature 23.4°C; Mean DO 9.8 mg/L; pH 8.4 • July Hypolimnion – Mean Temperature 17.5°C; Mean DO 0.5 mg/L; pH 6.7 Higher wind speeds on the sample day, along with cooler temperatures increased the depth of the epilimnion from three meters in July to five meters in August. The greatest DO and pH occurred in August. • August Epilimnion – Mean Temperature 22.4°C; Mean DO10.7 mg/L; pH 8.9 • August Hypolimnion – Mean Temperature 17.5°C; Mean DO 0.5 mg/L; pH 6.8 The dissolved oxygen (DO) profile during July and August remained clinograde curve.