Report Includes: Water Quality of Lakes

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. In the hypolimnion, DO consumption increased as organic matter sank to the sediments.

5 Black Lake 2019 Black Lake - September 23, 2019 Black Lake - October 21, 2019

Temperature (°C), pH, DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0

1 1

2 2

3 3

4 4 Depth (meters) Depth (meters) 5 5

6 6 7 7 0 20 40 60 80 100 0 20 40 60 80 100 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 5. Vertical water quality profiles from BL2 at Black Lake collected during September and October 2019.

In September, air temperatures declined, especially overnight. Black Lake turned over. The mean DO supply fell to the season’s low. • September Temperature 18.3°C; DO 7.6 mg/L; pH 7.4

In October, the temperature dropped 5.5°C. The mean DO concentration increased compared to September. • October – Temperature 12.8°C; DO 8.7 mg/L; pH 7.1

Transparency and Color

Transparency of water to light has been used to approximate turbidity and phytoplankton populations. Secchi depth is closely correlated with the percentage of light transmission through water. The depth at which the Secchi disk is no longer visible approximates 10% of surface light, however suspended particles in the water affect accuracy. The health department recommends visibility of at least 1.2 meters, or four feet, at public swimming beaches.

Color can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. High concentrations of algae cause the water color to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown.

6 Black Lake 2019

2019 Black Lake - Transparency, Color, and Chlor-a

May June July August September October 0.00 50 45 0.50 40 35 a (µg/L)

1.00 30 - 25 1.50 20 15 Chlorophyll

Secchi depth (meters) 2.00 10 5 2.50 0 Secchi Depth (meters) Chl a (µg/L)

Figure 6. Secchi depth, chlorophyll-a concentration, and color of the lake water at BL2 in 2019.

The transparency statistics (meters) for 2019: • mean and median 1.4 • minimum 0.7 in September • standard deviation 0.6 • maximum 2.2 in June

Transparency was negatively correlated to chlorophyll-a concentration (R²=0.87). Transparency was excellent (mean 1.9 meters) from May to July when productivity was lower (mean 11.3 µg/L). Transparency declined dramatically from August to October (mean 0.9 meters) when productivity was greater (mean 35.3 µg/L). Figure 8 shows the average transparency compared to the long-term average (LTA). In 2019, transparency was 0.6 meters lower than the LTA.

Black Lake - Transparency (meters) Annual Average Minus Long-Term Average 1.5

1.0

0.5

LTA 0.02.0

-0.5

-1.0

Figure 6. Transparency at BL2 compared to the long-term average (LTA).

7 Black Lake 2019 Productivity

Pigments

Chlorophyll-a pigment is present in algae and cyanobacteria and is widely used to assess the abundance of phytoplankton in suspension. Phaeophytin is also a pigment, but it is not active in photosynthesis. It is a breakdown product of chlorophyll and is present in dead suspended material (Moss, 1967). Phaeophytin absorbs light in the same region of the spectrum as chlorophyll-a, and, if present can interfere with acquiring an accurate chlorophyll-a value. Phaeopigments have been reported to contribute 16 to 60% of the measured chlorophyll-a content (Marker et al., 1980). The ratio of chlorophyll-a to phaeophytin-a has been used as an indicator of the physiological condition of phytoplankton in the sample.

2019 Productivity Data

Figures 9 shows that the highest concentration of chlorophyll-a and phaeophytin-a occurred in August and September. The 2019 statistics for chlorophyll-a concentration (µg/L) are: • mean 23.3 • minimum 10.0 in June • median 18.5 • maximum 45.0 in September • standard deviation 14.6

2019 Black Lake - Chlor-a, Ratio Chlor-a to Phaeo-a, and DO

50 40

40 30

30 µg/L) a (

- 20

20 µg/L) and DO (mg/L) a (

Chlorophyll 10

0 0 - Phaeophytin May June July August September October

Chlorophyll-a Ratio Chlor-a : Phaeo-a Surface DO

Figure 7. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments and DO concentration in the photic zone or epilimnion collected at BL2. In 2019, TCEH sampled Black Lake five times for algal toxins. These samples were collected in August (2 samples), September (2 samples), and October (1 sample). None of the samples exceeded the Washington State Toxic Algae Advisory Levels. The Black Lake Special District applied alum in April 2016, which reduced TP at the surface and bottom of the lake. No toxic algae blooms have been detected since the alum application.

8 Black Lake 2019 Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998) Figure 10 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at BL2 in 2019.

Black Lake - 2019 Surface Total Phosphorus & Total Nitrogen 1.000 0.080 0.070 0.800 0.060 0.600 0.050 0.040 TP (mg/L) TP

TN (mg/L) TP Action Level 0.02 mg/L 0.400 0.030 0.020 0.200 0.010 0.000 0.000 May June July August September October

Surface TN Surface TP

Figure 10. 2019 surface concentration of TP and TN at BL2.

The mean surface TP concentration exceeded the state action level (purple line at 0.020 mg/L). The 2019 concentration of TP and TN in surface waters was highest in September, when the lake turned over. Thermal stratification reduced internal loading to surface waters from May to August; changes in the phytoplankton community and external sources likely affect nutrient levels during stratification.

Total Phosphorus

Compared to the rich supply of other elements required for nutrition or structure, phosphorus is the least abundant and most commonly limits biological productivity. Lakes in this region experience undesirable algae growth when the annual average surface phosphorus level reaches 0.030 mg/L (Gilliom, 1983). Washington adopted numeric action values in the state water quality standards to protect lakes. The action level for the Puget Lowlands ecoregion is 0.020 mg/L (WAC, 2019). Figure 11 displays the TP concentration at BL2.

The concentration was higher at the bottom in July and August because Black Lake was thermally stratified mid-summer. During stratification, the hypolimnion was mostly stagnant, not mixing with the oxygenated water above. At the same time, oxygen in the hypolimnion was consumed by redox processes like decomposition. Due to the lack of oxygen near the bottom, phosphorus stored in the sediments was released into the water column. This phosphorus accumulated in the hypolimnion, until turn-over later in the fall.

9 Black Lake 2019 Black Lake - 2019 Total Phosphorus 0.80 0.70 0.60 0.50 0.40 TP Action Level mg/L 0.30 0.02 mg/L 0.20 0.10 0.00 May June July August September October Surface TP Bottom TP

Figure 11. Concentration of Total Phosphorus at the surface and bottom at BL2 in 2019.

TP concentration statistics are: • TP Surface Mean 0.037 mg/L • TP Bottom Mean 0.282 mg/L • TP Surface Median 0.031 mg/L • TP Bottom Median 0.159 mg/L • TP Surface Std Dev 0.017 mg/L • TP Bottom Std Dev 0.253 mg/L

Figure 12 displays the average annual concentration of total phosphorus at BL2 from 2008 to 2019. Since Black Lake Special District applied alum in 2016, both the surface and bottom concentrations have fallen drastically.

Black Lake - Total Phosphorus Annual Summer Averages 1.40 1.20 1.00 0.80

mg/L 0.60 TP Action Level 0.02 mg/L 0.40 0.20 0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TP Bottom TP

Figure 12. Average Annual Total Phosphorus at BL2 from 2008 to 2019.

Comparing years pre-alum (2008-2015) to post alum application (2016-2019), the TP concentration was reduced by (mg/L): • mean surface 0.417 • mean bottom 0.490 • median surface 0.429 • median bottom 0.378 • standard deviation surface 0.078 • standard deviation bottom 0.217 • minimum surface 0.297 • minimum bottom 0.305 • maximum surface 0.037 • maximum bottom 1.013

10 Black Lake 2019 Nitrogen

Black Lake - 2019 Total Nitrogen

2.0

1.5

1.0

mg/L 0.5

0.0 May June July August September October

Surface TN Bottom TN

Figure 8. Concentration of Total Nitrogen at the surface and bottom at BL2 in 2019.

The total nitrogen concentration was higher at the bottom from June to August because the hypolimnion was hypoxic during stratification; ammonia-nitrogen was released from the bottom sediments and accumulated in the hypolimnion. The 2019 TN statistics (mg/L) are:

• surface mean 0.576 • bottom mean 0.880 mg/L • surface median 0.662 • bottom median 0.710 mg/L • surface standard deviation 0.202 • bottom standard deviation 0.462 mg/L • surface minimum 0.193 in May • bottom minimum 0.353 in May • surface maximum 0.803 in September • bottom maximum 1.660 in August

Figures 16 displays the average annual concentrations for total nitrogen from 2008 to 2019. The bottom concentration began to rise in 2015. The following year, the surface TN concentration increased over 75%. The surface concentration has continued to climb until 2019.

Black Lake - Total Nitrogen Annual Summer Averages 1.00 0.90 0.80 0.70 0.60 0.50

mg/L 0.40 0.30 0.20 0.10 0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN Bottom TN Figure 9. Average Annual Total Nitrogen at BL2 from 2008 to 2019. 11 Black Lake 2019 Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 17 shows the TN to TP ratio at the Black Lake site. Starting in 2016, the decline of TP concentrations combined with increase in TN concentrations altered the ratio. Black Lake has been phosphorus limited since 2016 when the Black Lake Special District applied alum.

Black Lake - TN to TP Ratio 100 Phosphorus Limited 10

1 Nitrogen Limited

0.1 TN:TP (mg/L)

0.01 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TN:TP

Figure 17. TN:TP at BL2 from 2008 to 2019.

Trophic State Indices (TSI)

The most commonly used method to classify lakes is called the Carlson’s Trophic State Index (Carlson, 1977). Based on the productivity, this method uses three index variables: transparency (Secchi disk depth), chlorophyll-a, and phosphorus concentrations. Table 3 provides the index values for each trophic classification. Table 3. Trophic State Index variables. TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

For Black Lake, the 2019 TSI results are: • Chlorophyll-a: 61 eutrophic • Total Phosphorus:56 eutrophic • Secchi Disk: 55 eutrophic

The average of the three TSI variables is 57, which categorizes Black Lake as eutrophic in 2019. Based on the chlorophyll-a concentration, Black Lake has been classified as eutrophic since 2008 (Figure 20). Black Lake has been classified as eutrophic a majority of sample seasons since 2008: • 100% for chlorophyll-a • 92% for TP concentration (every year except 2016) • 66% for Secchi depth

12 Black Lake 2019 Black Lake - Trophic State Indices 100

TSI ValueTSI Eutrophic 50 Mesotrophic 40 Oligotrophic 30 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Chlorophyll-a TSI TP TSI Secchi TSI Figure 10. BL2 Trophic State Index from 2008 to 2018.

SUMMARY

Thermal Stratification 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 temperature and oxygen concentration declined with depth. Black Lake turned over in September 2019.

Transparency The mean and median transparency was 1.4 meters. The average transparency was 0.6 meters lower than the long-term average. Transparency was negatively correlated to chlorophyll-a concentration. Transparency was excellent from May to July when productivity was lower. When productivity increased from August to October, transparency declined dramatically.

Chlorophyll-a In 2019, the mean concentration of chlorophyll-a was 23.3 µg/L. The greatest productivity occurred the second half of the sample season. Between August and October, TCEH sampled Black Lake five times for algal toxins. None of the samples exceeded the Washington State Toxic Algae Advisory Levels. No toxic algae blooms have been detected since the 2016 alum application.

Nutrients The mean surface TP concentration was 0.037 mg/L, which is above the action level of 0.020 mg/L. The Black Lake Special District applied alum in 2016, reducing both the surface and bottom TP concentrations.

Classified as Eutrophic In 2019, the Black Lake site BL2 was classified as eutrophic based on an average of the three TSI variables. The TSI trend from 2008 to 2018 was toward higher productivity. No trends were found for the TSI scores for TP concentrations and transparency (TCEH, 2018).

Black Lake 2019 DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 https://www.co.thurston.wa.us/health/ehrp/annualreport.html For digital data contact: [email protected] For correction, questions, and suggestions, contact the author of the 2019 report: [email protected]

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Marker, A.E., Nusch, H. Rai and Rieman, B. 1980. The measurement of photosynthetic pigments in freshwaters and the standardization of methods: conclusions and recommendations. Arch. Hydrobio. Beih. Ergebn. Limnol. 14:91-106.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

TCEH. 2009. Surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring. Thurston County Environmental Health. Olympia, WA.

TCEH. 2018. Black Lake Water Quality Report. Thurston County Environmental Health. Olympia, WA.

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

14 Black Lake 2019 Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control Appendix C. Toxic Algae

15 Black Lake 2019

Appendix A. Raw data

Table A-1 Raw data collected at the Black Lake site BL2. Profile Samples Site INFO Temp ( C ) pH DO (m/l) Conductivity (Sp) Turb (FNU) TP TN Composite Sample Site Time Bottom Bottom Total Description (first Secchi Water Profile Sample Date Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a /Common sample (m) Color Depth Depth (m) Name taken) (m) (m) Black 5/21/2019 14:11 8.4 1.80 5 8.0 17.550 12.493 8.10 6.91 9.79 0.59 88.5 105.5 1.81 3.93 7.9 0.026 0.125 0.193 0.353 12.0 0.6 Black 6/17/2019 15:43 8.25 2.20 3 7.5 23.663 14.723 8.19 6.64 9.70 0.50 94.1 114.2 0.02 0.28 7.75 0.020 0.193 0.444 0.516 10.0 1.0 Black 7/23/2019 15:52 8.18 1.75 6 6.5 23.536 16.750 8.54 6.78 10.09 0.45 97.0 131.1 -21.98 -6.83 7.5 0.022 0.553 0.670 1.330 12.0 1.8 Black 8/26/2019 15:24 8.59 0.97 6 7.5 22.683 16.863 8.93 6.80 10.93 0.44 100.5 165.9 8.23 3.48 8 0.035 0.702 0.653 1.660 36.0 1.1 Black 9/23/2019 13:55 8.28 0.72 3 8.0 18.429 18.034 7.48 7.24 8.24 7.81 105.0 106.7 10.15 9.23 8 0.067 0.062 0.803 0.748 45.0 1.9 Black 10/21/2019 14:48 8.3 1.00 3 8.0 12.769 12.693 7.15 7.08 8.76 8.66 104.5 104.5 7.86 7.24 8.00 0.049 0.054 0.692 0.671 25.0 0.0

16 Black Lake 2019

Appendix B. Quality Assurance/Quality Control

Table B-1 provides the amount of instrument drift for specific conductivity, dissolved oxygen (collected with optical sensor), and pH. The temperature thermistor was checked against a NIST thermometer on October 24, 2019 and difference was 0.03° C. TCEH collected 15% field replicates and blanks for TP, TN. Chlorophyll-a, and Phaeophytin-a.

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

St Clair, Summit, Hicks 5/21/2019 7:05 0.07 0.96 0.71 Ward, Pattison, Long, Black 5/22/2019 7:15 0.01 0.10 0.28 Deep, Offut, Lawrence 5/23/2019 7:10 -0.03 -0.71 0.14 St Clair, Summit, Black 6/18/2019 7:15 0.14 -0.48 0.57 Ward, Hicks, Pattison, Long 6/19/2019 7:20 0.06 0.30 0.00 Deep, Offut, Lawrence 6/20/2019 20:00 0.05 -7.18 0.57 St Clair, Summit, Black 7/24/2019 7:50 0.08 0.08 0.14 Deep, Offut, Lawrence 7/25/2019 8:00 0.03 0.01 0.14 Ward, Hicks, Pattison, Long 7/26/2019 16:20 0.09 -6.62 0.43 St Clair, Summit, Black 8/27/2019 7:15 0.00 0.11 0.00 Deep, Offut, Lawrence 8/28/2019 7:30 0.11 -0.36 0.14 Ward, Hicks, Pattison, Long 8/29/2019 7:30 0.26 -0.33 0.29 St Clair, Summit, Black 9/24/2019 7:30 0.21 -0.12 0.00 Deep, Offut, Lawrence 9/25/2019 7:15 0.16 0.20 0.00 Ward, Hicks, Pattison, Long 9/26/2019 13:30 0.57 -0.12 0.14 St Clair, Summit, Black 10/22/2019 7:30 -0.16 -1.31 0.00 Ward, Hicks, Pattison, Long 10/23/2019 7:30 -0.03 0.76 0.14 Deep, Offut, Lawrence 10/24/2019 13:15 -0.03 0.91 0.57 Median Percent Difference: 0.06 -0.06 0.14 Mean Percent Difference: 0.09 -0.77 0.24

17 Black Lake 2019

Table B-2. Relative Percent Difference of field replicates collected during the 2019 sample season. TP TN TN Chl a Phae a TP Surface TP TP TN TN TN TN Chl a Chl a Phae a Phae a Time TP Surface Bottom Surface Bottom COMP COMP Site Date Surface TP Bottom Bottom Surface Surface Bottom Bottom COMP COMP COMP COMP PDT Dup (mg/L) Dup Dup Dup Dup Dup (mg/L) % RPD (mg/L) % RPD (mg/L) % RPD (mg/L) % RPD (µg/L) % RPD (µg/L) % RPD (mg/L) (mg/L) (mg/L) (µg/L) (µg/L) Hicks QA 5/20/2019 15:36 0.012 0.011 8.7 0.131 0.111 16.5 0.264 0.213 21.4 0.511 0.521 1.9 3.2 3.2 0.0 1.1 1.1 0.0 Deep QA 5/22/2019 10:56 0.011 0.013 16.7 0.037 0.034 8.5 0.317 0.366 14.3 0.655 0.616 6.1 4.3 4.3 0.0 0.6 0.4 40.0 Black QA 6/17/2019 15:43 0.02 0.021 4.9 0.193 0.194 0.5 0.444 0.341 26.2 0.516 0.656 23.9 10 10.0 0.0 1 1.2 18.2 Deep QA 6/19/2019 11:10 0.018 0.017 5.7 0.076 0.057 28.6 0.362 0.377 4.1 1.15 1.040 10.0 9.3 19.0 68.6 1.9 2.4 23.3 SC1 QA 7/23/2019 12:02 0.019 0.020 5.1 4.01 3.930 2.0 0.311 0.316 1.6 14.6 14.500 0.7 2.5 3.6 36.1 1 1.1 9.5 LL1 QA 7/24/2019 13:06 0.036 0.039 8.0 0.499 0.557 11.0 1.26 1.130 10.9 1.92 3.180 49.4 7.7 8.3 7.5 2.5 1.8 32.6 Summit QA 8/26/2019 13:17 0.009 0.008 11.8 0.018 0.015 18.2 0.128 0.149 15.2 0.188 0.204 8.2 1.1 1.2 8.7 0.4 0.4 0.0 Ward QA 8/28/2019 13:05 0.006 0.006 0.0 0.746 0.789 5.6 0.285 0.283 0.7 3.52 3.610 2.5 1.9 2.1 10.0 0.7 1.2 52.6 LL2 QA 9/24/2019 14:07 0.061 0.061 0.0 0.071 0.072 1.4 1.1 1.140 3.6 1.3 1.350 3.8 30 23.0 26.4 4.3 4.2 2.4 LO3 QA 9/25/2019 12:48 0.063 0.058 8.3 0.045 0.045 0.0 0.849 0.760 11.1 0.502 0.512 2.0 42 50.0 17.4 4.2 3.3 24.0 Hicks QA 10/23/2019 9:40 0.027 0.027 0.0 0.078 0.062 22.9 0.369 0.404 9.1 0.639 0.604 5.6 9.8 8.8 10.8 3.5 2.2 45.6 Pattison QA 10/23/2019 10:57 0.057 0.058 1.7 0.069 0.068 1.5 0.644 0.640 0.6 0.581 0.650 11.2 20 25.0 22.2 5.9 6.6 11.2 Mean RPD 5.9 Mean RPD 9.7 Mean RPD 9.9 Mean RPD 10.4 Mean RPD 17.3 Mean RPD 21.6 Median RPD 5.4 Median RPD 7.0 Median RPD 10.0 Median RPD 5.9 Median RPD 10.4 Median RPD 20.7

Table B-3. Field blanks collected during the 2019 sample season. Blanks Site Date Time TP TN Composite Sample Hicks QAB 5/20/2019 15:36 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Deep QAB 5/22/2019 10:56 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Black QAB 6/17/2019 15:43 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Deep QAB 6/19/2019 11:10 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 SC1 QAB 7/23/2019 12:02 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 LL1 QAB 7/24/2019 13:06 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Summit QAB 8/26/2019 13:17 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Ward QAB 8/28/2019 13:05 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 LL2 QAB 9/24/2019 14:07 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 LO3 QAB 9/25/2019 12:48 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Hicks QAB 10/23/2019 9:40 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1 Pattison QAB 10/23/2019 10:57 <0.002 <0.050 <0.002 <0.050 <0.1 <0.1

18 Black Lake 2019

Appendix C. Toxic Algae

2019 Deep Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Deep Lake map showing location of sample site DP1.

PART OF BLACK RIVER WATERSHED A private resort is located on the east side of the lake. • SHORELINE LENGTH: 1.4 miles • LAKE SIZE: 0.10 square miles (66 acres) GENERAL TOPOGRAPHY: • BASIN SIZE: 1.2 square miles The approximate altitude of the lake is 198 • MEAN DEPTH: 3.7 meters (12 feet) feet. The lake is situated between gentle hills • MAXIMUM DEPTH: 5.2 meters (17 feet) (elevation 300 feet). There is a small unnamed • VOLUME: 770 acre-feet inlet on the southeast side of the lake and an unnamed outlet on the northwest side of the PRIMARY LAND USES: lake. The outlet creek flows into Scott Lake. Most of the watershed is inside Millersylvania State Park, a 903-acre park used for camping, GENERAL WATER QUALITY: hiking, and water recreation. The sample site Good – In 2019, Deep Lake was classified as DP1 is in the deepest part of the lake (Figure 1). mesotrophic. Transparency was lower than the long-term average. However, overall PRIMARY LAKE USE: transparency has improved over the last Deep Lake is used for fishing, swimming, and decade. The Total Phosphorus (TP) surface boating. concentration was in the mesotrophic range in 2019, for the first time in nine years. The PUBLIC ACCESS: surface TP at Deep Lake has been below the Millersylvania State Park has three swimming action level every year except 1975 for beaches that are very popular in the summer. mesotrophic lakes in the Puget Lowlands. The surface TP concentration trended down since 2008. Algal blooms commonly occur from Deep Lake 2019 August to November. More algae samples have 2015 was the last time toxins over advisory been collected over the last two years, but levels were detected.

DESCRIPTION

Deep Lake is a small, shallow lake in central Thurston County south of Tumwater, Washington. Public access to Deep Lake is at Millersylvania State Park, a popular swimming, fishing, and water recreation area. Approximately two-thirds of the shoreline is within the 903-acre park. In addition to two swimming beaches and kayak rentals, Millersylvania has forest and wetland habitats, miles of trails, campsites, kitchen shelters. A small RV resort exists on the eastern shore.

The Washington Department of Fish and Wildlife stocks rainbow trout and the lake supports natural populations of largemouth bass, yellow perch, bluegill, and pumpkinseed sunfish. Dense stands of aquatic macrophytes grow in the littoral zones. Deep Lake was listed for bacteria in 2005 based on E. coli exceeding Part 2 of the fecal coliform standard.

METHODS

In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Deep Lake from May to October. Data are collected in the deepest part of the lake basin at sample site DP1 shown in Figure 1. 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 color of the lake water since the 1990s.

2 Deep Lake 2019

Figure 2. TCEH compared color of the lake water to the Custer Color Strip.

Quality Assurance and Quality Control (QA/QC)

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 the Olympia regional weather station. Temperature (ᵒ C) Month Weather on Sample Day Monthly Average (Low/High) May Mostly Cloudy (17°C); 0-6 mph WSW wind 15 (2/30) June Fair (12°C); 13-20 mph W wind 15 (4/33) July Fair to Cloudy (11°C); 0-10 mph SSW wind 18 (8/32) August Fair (24°C); 0-12 mph NE wind (20 mph gusts) 18 (7/33) September Cloudy (18°C); 0-8 mph WSW wind 14 (-1/26) October Fair (14°C); 0-8 mph SSW wind 8 (-6/18)

Vertical Water Quality Profiles

The vertical water quality profiles illustrate how the water column at Deep Lake changed over the sample season (Figures 3 to 5).

3 Deep Lake 2019

Deep Lake - May 22, 2019 Deep Lake - June 19, 2019 Temperature (°C), pH (std) , DO (mg/L) Temperature (°C), pH (std), DO (mg.L) 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 0

1 1

2 2

3 3 Depth (meters) Depth (meters) 4 4

5 5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC µS/cm SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 3. Vertical water quality profiles for DP1 collected in May and June 2019.

In May, this shallow lake was weakly stratified. DO was supersaturated, particularly in the metalimnion creating a positive heterograde DO curve. • May Epilimnion 1.5m deep – 17.2°C; pH 7.5, DO 10.9 mg/L • May Hypolimnion 0.5 meter above bottom – 9.7°C; pH 6.2, DO 0.9 mg/L

In June, the water column was supersaturated with oxygen to a depth of 3.5 meters. • June Epilimnion 1.5meter deep – 20.0°C; pH 7.7, DO 11.3 mg/L • June Hypolimnion 0.5 meter above bottom – 10.6°C; pH 5.9, DO 1.7 mg/L

In May and June Secchi depth ranged from 3.2 to 2.2 meters respectively at DP1, a site that is just over five meters deep. Sunlight penetrated deeper into the water column, into the metalimnion. Sunlight permitted photosynthesis in deeper water, as indicated by the higher pH above 2.5 meters depth. Excess oxygen accumulated in the metalimnion, due to the reduced mixing of the water column, creating a positive heterography DO profile (Wetzel, 1983). Abundant aquatic macrophytes and benthic algae at Deep Lake likely also contribute to DO supersaturation.

4 Deep Lake 2019 Deep Lake - July 24, 2019 Deep Lake - August 27, 2019

Temperature (°C), pH (std), DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 0

1 1

2 2

3 3 Depth (meters) Depth (meters)

4 4

5 5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 4. Vertical water quality profiles for DP1 collected in July and August 2019.

In July, the epilimnion grew one meter deeper. The DO profile remained positive heterograde. • July Epilimnion 2.5 meters deep– 21.9°C; pH 7.8, DO 10.9 mg/L • July Hypolimnion 0.5 meter above the bottom – 11.8°C; pH 5.8, DO 1.0 mg/L

In August, high winds with gusts up to 20 mph, mixed the epilimnion. A thick layer of algae covered the lake bottom. • August Epilimnion 2.5 meters deep – 21.3°C; pH 7.7, DO 10.8 mg/L • August Hypolimnion 0.5 meter above the bottom – 13.2°C; pH 5.7, DO 1.5 mg/L

5 Deep Lake 2019 Deep Lake - September 24, 2019 Deep Lake - October 22, 2019

Temperature (°C), pH, DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 0

1 1

2 2

Depth (meters) 3 3 Depth (meters)

4 4

5 5 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 5. Vertical water quality profiles from DP1 collected in September and October 2019.

In September, air temperatures declined, especially overnight. The epilimnion cooled almost 4°C. Cooler water sank, starting the mixing process. • September Epilimnion 2.5 meters deep – 17.7°C, pH 7.3, DO 10.9 mg/L • September Hypolimnion 0.5 meter above the bottom – 12.9°C, pH 5.8, DO 0.9 mg/L

In October, the change of seasons was evident. The average and minimum temperatures declined 5 to 6°C. Deep Lake had almost completely turned over. • October Photic Zone (Secchi Depth 3.8 meters) – 12.0°C, pH 6.8, DO 8.6 mg/L • October Bottom Measurements (4.5 to 5 meters) – 11.8°C, pH 6.5, DO 6.6 mg/L

Water Transparency and Color

Color can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. High concentrations of algae cause the color of the lake water to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown. Figure 6 shows the transparency and color for Deep Lake for 2019.

6 Deep Lake 2019

2019 Deep Lake - Transparency, Color, and Chlor-a

May June July August September October 0.00 10.0

0.50 9.0 8.0 1.00 7.0

1.50 a (µg/L) 6.0 - 2.00 5.0

2.50 4.0 3.0 chlorophyll

Secchi depth (meters) 3.00 2.0 3.50 1.0 4.00 0.0

Secchi Depth Chl a (µg/L)

Figure 6. Color of the lake water, Secchi depths, and chlorophyll-a concentrations at DP1 in 2019.

In 2019, transparency was lowest in June (2.2 meters) and highest in October (3.8 meters). The mean and median transparency for the sample season was 3.1 meters. The color of the water (shown as the bar color in Figure 6), based on the reference Custer Color Strip. Transparency was inversely related to chlorophyll-a concentration (R²=0.77). Lake color was likely affected by changes in the algae and cyanobacteria communities; phytoplankton identification would provide more information about productivity and phytoplankton assemblages.

Deep Lake Transparency (meters) Annual Average Minus Long-Term Average 1.50

1.00

0.50

LTA 0.003.8 meters -0.50

-1.00

-1.50

Figure 7. Transparency at DP1 compared to the long-term average (LTA).

7 Deep Lake 2019

Productivity

Pigments

2019 Productivity Data

In 2019, the chlorophyll-a concentration was: • mean 6.23 µg/L • minimum 4.30 µg/L in May • median 5.50 µg/L • maximum 9.30 µg/L in June • standard deviation 2.16 µg/L

Figure 8 shows that the highest concentration of chlorophyll-a occurred in June and when the lake started to mix in September. The greatest ratio of chlorophyll-a to phaeophytin-a occurred in May, dropping each month until October.

Deep Lake - 2019 Chlor-a, Ratio Chlor-a to Phaeo, and DO

12 12

10 10

8 8 µg/L) a (

- 6 6 µg/L) and DO (mg/L) a ( 4 4 Chlorophyll 2 2 - Phaeophytin 0 0 May June July August September October

Chlorophyll-a Ratio Chlor-a : Phaeo-a Surface DO

Figure 8. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments, and DO concentration in the photic zone or epilimnion collected at DP1 in 2019.

8 Deep Lake 2019

In 2019, TCEH collected seven algae samples: two in late August, four in September, and one in early October. These samples were tested for one or more of the following toxins: anatoxin-a, microcystin, cylindrospermopsin, and/or saxitoxin. None of the samples exceeded the Washington State advisory levels for these four toxins (Appendix C).

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998). Figure 9 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at Deep Lake.

Deep Lake - Surface Total Phosphorus & Total Nitrogen 0.450 0.020 0.400 0.018 0.350 0.016 0.014 0.300 TP Action Level 0.012 0.250 0.020 mg/L 0.010 0.200 0.008

0.150 (mg/L) TP

TN (mg/L) 0.006 0.100 0.004 0.050 0.002 0.000 0.000 May June July August September October Surface TN Surface TP

Figure 9. 2019 surface concentration of TP and TN at DP1.

The concentration of TP remained below the action level the entire season. TP peaked in June. The concentration of TN in surface waters was highest in July, when the lake was stratified. Both nutrients increased when mixing began in September and with turnover in October. Thermal stratification reduced internal loading to surface waters from June to August; changes in the phytoplankton community and external sources likely affect nutrient levels during stratification.

Total Phosphorus

Compared to the rich supply of other elements required for nutrition or structure, phosphorus is the least abundant and most commonly limits biological productivity. Lakes in this region experience undesirable algae growth when the annual average surface phosphorus level reaches 0.030 mg/L (Gillion, 1983). Washington adopted numeric action values in the state water quality standards to protect lakes. The action level for the Puget Lowlands ecoregion is 0.020 mg/L (WAC, 2019). Figure 10 displays the TP concentration at Deep Lake.

9 Deep Lake 2019 Deep Lake - Total Phosphorus

0.20 0.18 0.16 Action 0.14 Level 0.020 0.12 mg/L 0.10 0.08 mg/L 0.06 0.04 0.02 0.00 May June July August September October

Surface TP Bottom TP

Figure 10. Concentration of Total Phosphorus at the surface and bottom at DP1 in 2019.

The 2019 statistics for TP are: • TP Surface Mean 0.014 mg/L • TP Bottom Mean 0.064 mg/L • TP Surface Median 0.014 mg/L • TP Bottom Median 0.057 mg/L • TP Surface Std Dev 0.004 mg/L • TP Bottom Std Dev 0.062 mg/L • TP Surface Minimum 0.009 mg/L in Aug • TP Bottom Minimum 0.007 mg/L in Aug • TP Surface Maximum 0.018 mg/L in June • TP Bottom Maximum 0.176 mg/L in July

Figure 11 displays the average annual concentration of total phosphorus at DP1 from 1974 to 1975 and 1994 to 2019. The mean annual surface TP was above the state action level (purple line at 0.020 mg/L) one time, in 1975, which included winter samples. The May to October sample season was not standardized until 1996.

Deep Lake - Total Phosphorus Annual Summer Averages 0.10

0.08

0.06 Action Level 0.020 0.04 mg/L mg/L

0.02

0.00 1974 1975 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Sur TP Bott TP

Figure 11. Average Annual Total Phosphorus at DP1 from 1974 to 1975 and 1994 to 2019.

10 Deep Lake 2019

For the period of record: TP Surface TP Bottom • Mean 0.010 mg/L • Mean 0.026 mg/L • Median 0.009 mg/L • Median 0.015 mg/L • Std Dev 0.003 mg/L • Std Dev 0.020 mg/L • Minimum 0.006 mg/L in 2000 • Minimum 0.009 mg/L in 1994 • Maximum 0.021 mg/L in 1975 • Maximum 0.090 mg/L in 2012

Nitrogen

The TN statistics for DP1 are: TN Surface TN Bottom • Mean 0.339 mg/L • Mean 0.868 mg/L • Median 0.340 mg/L • Median 0.843 mg/L • Std Dev 0.051 mg/L • Std Dev 0.550 mg/L • Minimum 0.261 mg/L in Aug • Minimum 0.260 mg/L in Aug • Maximum 0.418 mg/L in July • Maximum 1.840 mg/L in July

Deep Lake - Total Nitrogen

2.0 1.8 1.6 1.4 1.2 1.0

mg/L 0.8 0.6 0.4 0.2 0.0 May June July August September October

Surface TN Bottom TN

Figure 6. Concentration of Total Nitrogen at the surface and bottom at DP1 in 2019.

11 Deep Lake 2019 Figures 17 displays the average annual concentrations for total nitrogen from 1974 to 1975 and 1994 to 2019. The TN statistics TN for the period of record are: TN Surface TN Bottom • Mean 0.362 mg/L • Mean 0.591 mg/L • Median 0.328 mg/L • Median 0.453 mg/L • Std Dev 0.098 mg/L • Std Dev 0.342 mg/L • Minimum 0.263mg/L in 1997 • Minimum 0.278 mg/L in 1997 • Maximum 0.660 mg/L in 1974 • Maximum 1.652 mg/L in 2007

Deep Lake - Total Nitrogen Annual Summer Averages 1.60 1.40 1.20 1.00 0.80

mg/L 0.60 0.40 0.20 0.00 1974 1975 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Sur TN Bott TN

Figure 7. Average Annual Total Nitrogen at DP1 from 1974 to 1975 and 1994 to 2019.

Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 19 shows the TN to TP ratio at DP1. Deep Lake has been phosphorus limited for the period of record.

Deep at DP1 - TN to TP Ratio 100 Phosphorus Limited

Nitrogen Limited TN:TP (mg/L)

1 1974 1975 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TN:TP

12 Deep Lake 2019 Figure 8. TN:TP at DP1 from 1974 to 1975 and 1994 to 2019.

Trophic State Indices (TSI)

The most used method to classify lakes is called the Carlson’s Trophic State Index (Carlson, 1977). Based on the productivity, this method uses three index variables: transparency (Secchi disk depth), chlorophyll-a, and phosphorus concentrations. Table 3 provides the index values for each trophic classification. Table 3. Trophic State Index variables. TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

For DP1, the 2019 TSI results were: • Chlorophyll-a: 49 mesotrophic • Total Phosphorus: 42 mesotrophic • Secchi Disk: 43 mesotrophic

The average of the three TSI variables is 45, which categorizes DP1 as mesotrophic in 2019. Based on the chlorophyll-a concentration alone, DP1 has been classified as mesotrophic 63% of the last 27 sample seasons and eutrophic 30% (Figure 20). DP1 has been classified as mesotrophic: • 12% for TP concentration (1975, 2010, and 2019) • 58% for Secchi depth

Deep Lake - Trophic State Indices 65 60

55 Eutrophic 50 45 Mesotrophic 40 Oligotrophic TSI ValueTSI 35 30

25 20

1975 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Chlorophyll-a TSI TP TSI Secchi TSI

Figure 9. DP1 Trophic State Index from 1974 and 1994 to 2019.

13 Deep Lake 2019 SUMMARY

Thermal Stratification In 2019, the water column at Deep Lake began to stratify in May and June. The metalimnion was supersaturated with oxygen from May to August. The epilimnion began to cool in September. Deep Lake turned over in October.

Transparency In 2019, the mean and median transparency for the sample season was 3.1 meters, 0.67 meters lower than the long-term average. Transparency was lowest in June (2.2 meters) and highest in October (3.8 meters). Transparency was inversely related to chlorophyll-a concentration (R²=0.77).

Productivity In 2019, the mean/median chlorophyll-a concentration was 6.23/5.50 µg/L. The greatest concentration of chlorophyll-a occurred in June and again in September, when the epilimnion began to cool. The greatest ratio of chlorophyll-a to phaeophytin-a occurred in May, dropping each month until October.

TCEH collected seven algae samples in 2019: two in late August, four in September, and one in early October. These samples were tested for one or more of the following toxins: anatoxin-a, microcystin, cylindrospermopsin, and/or saxitoxin. None of the samples exceeded the Washington State advisory levels for these four toxins.

Nutrients

The mean/median TP concentration was 0.014 mg/L at the surface, below the action level (0.020 mg/L) for lower mesotrophic lakes in the Puget Sound Lowlands ecoregion. The long-term mean/median TP at Deep Lake is 0.010/0.009 mg/L. Deep Lake has been phosphorus limited for the period of record.

The mean surface TN in 2019 (0.339 mean mg/L) was lower than the long-term mean (0.362 mg/L). The median TN in 2019 (0.340 mg/L) was greater than the long-term median(0.328mg/L).

Classified as Mesotrophic In 2019, the Deep Lake site DP1 was classified as mesotrophic based on an average of the three TSI variables. For the period of record, the chlorophyll-a concentration classified Deep Lake as mesotrophic 63% and eutrophic 30%. The Secchi depth has been within the mesotrophic range 56% of the period of record. The TP concentration has typically (89%) categorized Deep Lake as oligotrophic. However, in 2019 the TP concentration was in the mesotrophic range. The last time that occurred was in 2010.

DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

14 Deep Lake 2019 Thurston County Environmental Health (360) 867-2626 https://www.co.thurston.wa.us/health/ehrp/annualreport.htmlFor digital data contact: [email protected] For correction, questions, and suggestions, contact the author of the 2019 report: [email protected]

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

TCEH. 2009. Surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring. Thurston County Environmental Health. Olympia, WA.

TCEH. 2019. Deep Water Quality Report. Thurston County Environmental Health. Olympia, WA

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Welch, E.B., Cooke, G.D. 1995. Internal phosphorus loading in shallow lakes: importance and control. Lake and Reservoir Management: 11(3): 273-81.

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

15 Deep Lake 2019 Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control Appendix C. Toxic Algae

16 Deep Lake 2019

Appendix A. Raw data

Table A-1 Raw data collected at the Deep Lake site DP1 Bottom Bottom Total Time Secchi Water Profile Sample Site Date Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a PDT (m) Color Depth Depth (m) (m) (m) Deep 5/22/2019 10:56 5.16 3.24 6 5.0 17.386 9.500 7.48 6.17 10.89 0.75 78.8 97.2 -0.32 9.73 5 0.011 0.037 0.317 0.655 4.3 0.6 Deep 6/19/2019 11:10 5.3 2.20 7 5.0 20.006 10.515 7.68 5.89 11.29 1.18 81.1 112.1 -0.64 37.22 4.7 0.018 0.076 0.362 1.150 9.3 1.9 Deep 7/24/2019 11:14 5.25 2.95 3 5.0 21.983 11.242 7.75 5.73 10.87 0.89 81.0 126.3 0.20 47.62 4.75 0.012 0.176 0.418 1.840 5.9 1.2 Deep 8/27/2019 11:28 5.11 3.58 7 4.5 21.356 13.235 7.73 5.70 10.76 1.45 82.4 94.6 0.42 6.76 5 0.009 0.007 0.261 0.260 4.3 1.0 Deep 9/24/2019 11:07 5.36 2.76 6 5.0 17.734 12.480 7.31 5.76 10.90 0.68 79.6 139.6 -0.04 47.85 4.75 0.017 0.012 0.303 0.275 8.5 2.5 Deep 10/22/2019 10:59 5.22 3.76 7 5.0 12.089 11.714 6.96 6.31 8.66 4.89 80.2 85.1 0.55 1.33 5.00 0.016 0.076 0.373 1.030 5.1 4.1 .

17 Deep Lake 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

18 Deep Lake 2019

19 Deep Lake 2019

Appendix C. Toxic Algae

2019 Thurston Co Recreation Advisory Level for Microcystin

2019 Thurston Co Recreation Advisory Level for Anatoxin-a

2019 Hicks Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Hicks Lake map showing location of sample site HK1.

HENDERSON INLET WATERSHED PUBLIC ACCESS: Washington Department of Fish and Wildlife • SHORELINE LENGTH: 2.4 miles public boat launch and City of Lacey Wanschers • LAKE SIZE: 0.25 square miles Park. • BASIN SIZE: 1.8 square miles • MEAN DEPTH: 18 feet (5.5 meters) GENERAL TOPOGRAPHY: • MAXIMUM DEPTH: 35 feet (10.7 meters) Approximate altitude of the lake is 162 feet. • VOLUME: 2,700 acre-feet The watershed is relatively flat with extensive wetlands between lakes including one south of PRIMARY LAND USES: Hicks Lake. The watershed is primarily urban and suburban residential with a small percentage in 2019 GENERAL WATER QUALITY: undeveloped forest cover. Good –Water quality is generally considered good and supports the beneficial uses of this PRIMARY LAKE USES: mesotrophic lake. In 2019, the average surface Fishing, boating, water sports, and swimming. phosphorus concentration was close to the long-term average, below the state action level.

Hicks Lake 2019 DESCRIPTION

Hicks Lake is a relatively small lake, popular for fishing, boating, and swimming. It is the first lake in a chain of four hydraulically connected lakes. The four, Hicks, Pattison, Long and Lois, eventually discharge to Henderson Inlet via Woodland Creek. The lake has public access open six months per year provided by a Washington Department of Fish and Wildlife (WDFW) boat launch. WDFW stocks the lake with rainbow trout yearly, and periodically with brown trout. The City of Lacey’s Wanschers Community Park, on the west side of the lake, provides good shoreline access.

METHODS

In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring (Table 1) at the site identified as HK1 at Hicks Lake from May to October. Figure 1 shows the sample site, located in the deepest basin of the lake.

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 Desk • 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 Chlorohyll-a µg/L Multiple Grab Photic Zone Samples Composite of Phaeo-a µg/L Multiple Grab Photic Zone Samples Composite of Algae Genera, Present, Dominant, Multiple Grab Photic Zone Identification* Subdominant Samples

TCEH observed the color of the water against the white background of the Secchi disk at one-meter depth and compared it to the Custer Color Strip (Figure 2).

Hicks Lake 2019

Figure 2. TCEH compared the color of the water on the Secchi disk (1 m) to the Custer Color Strip

Quality Assurance and Quality Control (QA/QC)

Each sample day TCEH collected 10% replicate samples and trip blanks to assess total variation for laboratory samples (TCEH samples 3-4 lakes per day). Water quality data was collected with a Yellow Springs Instrument (YSI) EXO 1. The instrument was calibrated before each sample day. Instrument drift data were routinely collected within 24 hours of the sampling event. See Appendix C 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 monthly average, minimum, and maximum air temperatures. Temperature (ᵒ C) Month Weather on Sample Day Monthly Average (Low/High) May Cloudy, occasional light rain (13ᵒ C); 0-5 mph S wind 13 (2/30) June Cloudy (14ᵒ C); 0-9 mph SW wind 15 (4/33) July Fair, (25ᵒ C); 0-7 mph Variable wind 18 (8/32) August Fair, (22ᵒ C); 0-7 mph NNE wind 18 (7/33) September Mostly cloudy (13ᵒ C); Calm, 0-3 mph E wind 14 (-1/26) October Cloudy (7ᵒ C); Calm, 0-2 E wind 8 (-5/18)

Vertical Water Quality Profiles

Hicks Lake 2019

The vertical water quality profiles illustrate how the water column at Hicks Lake changed over the 2019 sample season. (Figures 3 to 5).

Hicks Lake - May 20, 2019 Hicks Lake - June 18, 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 6 6 Depth (meters)

Depth (meters) 7 7 8 8 9 9 10 10 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 collected at HK1 for May and June 2019.

In May, Hicks Lake was in the process of stratifying. DO at the surface was relatively high. • May Epilimnion – Temperature 18.5 °C; DO 9.5 mg/L • May Hypolimnion – Temperature 7.6°C; DO 1.5 mg/L

In June, the mean and minimum air temperatures increased. Surface water to retain heat, it was 2°C warmer than in May. DO declined. • June Epilimnion – Mean Temperature 21.5°C; Mean DO 9.1 mg/L • June Hypolimnion – Mean Temperature 7.6°C; Mean DO 0.5 mg/L

Thermal stratification created density differences, which impaired mixing of the water column. The dissolved oxygen (DO) profile during May and June was a clinograde curve. The hypolimnion, cut-off from the atmosphere after stratification, lost oxygen to redox processes like decomposition and advection of low DO groundwater. The epilimnion had much higher DO because this layer gained oxygen from the atmosphere and photosynthesis.

Hicks Lake 2019 Hicks Lake - July 25, 2019 Hicks Lake - August 28, 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 9 9 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 4. Vertical water quality profiles collected at HK1 for July and August 2019.

In July, the air temperature was the highest of the 2019 sample season. Likewise, the water temperature of the epilimnion increased to the summer’s peak. DO continued to decline. Three distinct layers were readily discernable, indicating that density differences hindered mixing of the water column. • July Epilimnion – Mean Temperature 22.4°C; Mean DO 8.4 mg/L • July Hypolimnion – Mean Temperature 8.9°C; Mean DO 0.5 mg/L

The average air temperature remained the same in August. The epilimnion grew deeper and increased productivity produced a greater supply of oxygen compared to July. • August Epilimnion – Mean Temperature 22.1°C; Mean DO 9.1 mg/L • August Hypolimnion – Mean Temperature 8.9°C; Mean DO 0.5 mg/L

The DO curve was clinograde in July and August 2019. The concentration of DO in the hypolimnion was low due to redox processes, which was isolated from more oxygenated water above by density differences during thermal stratification.

Hicks Lake 2019

Hicks Lake - September 25, 2019 Hicks Lake - October 23, 2019 Temperature (°C), pH (std), DO (mg/L) Temperature (°C), pH, 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)

6 Depth (meters) 6 7 7 8 8 9 9 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 5. Vertical water quality profiles collected at HK1 for September and October 2019.

In September, air temperatures declined, especially overnight. The surface water cooled and sank, which diminished temperature variation in the upper six meters of the water column. The DO curve remained clinograde in September. • September Epilimnion – Temperature 18.4°C; DO 7.9 mg/L • September Hypolimnion– Temperature 11.0°C; DO 0.6 mg/L

The change of seasons was evident in October. Air temperatures declined, surface waters cooled and sank, and water columns mixed. The water column was almost completely mixed during the October sampling event. • October Photic Zone (Secchi Depth 3.0 meters) – Temperature 12.8°C; DO 9.4 mg/L • October Bottom Measurement (9 meters) – Temperature 12.5°C; DO 6.9 mg/L

Transparency and Color

Color can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. The water color (not apparent color) observed each month is provided in Appendix A and Figure 6. High concentrations of algae cause the water color to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown.

Hicks Lake 2019 2019 Hicks Lake - Transparency, Color, and Chlor-a

May June July August September October 0.00 12.0 0.50 10.0 1.00 1.50 8.0 a (µg/L) 2.00 - 6.0 2.50 3.00 4.0 Chlorophyll Secchi depth (meters) 3.50 2.0 4.00 4.50 0.0 Secchi Depth (meters) Chl a (µg/L)

Figure 6. Color of lake water (bar color), Secchi depth (bar length), and chlorophyll-a concentration (purple line) from May to October 2019.

In 2019, mean and median transparency was 3.1 meters, ranging from the high of 3.9 meters in May to the low of 2.5 meters in August. In the early summer, when the chlorophyll-a concentration was 2 to 3 µg/L, the Secchi depth was above 3 meters. Transparency was reduced from August to October, when the chlorophyll-a concentration ranged higher: 5 to 10 µg/L.

Figure 7 shows the transparency annual average compared to the long-term average. Positive values reflect transparency better than the long-term average. Transparency was better than average six out of the past seven sample seasons.

Hicks Lake - Transparency (meters) Annual Average Minus Long-Term Average (LTA) 1.00 0.80 0.60 0.40 0.20 LTA0.00 2.4 -0.20 -0.40 -0.60 -0.80 -1.00

Figure 7. 2019 transparency at HK1 compared to the long-term average (LTA).

Hicks Lake 2019 Productivity

Pigments Chlorophyll-a pigment is present in all algae and is widely used to assess the abundance of algae in suspension. Phaeophytin is also a pigment, but it is not active in photosynthesis. It is a breakdown product of chlorophyll and is present in dead suspended material (Moss, 1967). Phaeophytin absorbs light in the same region of the spectrum as chlorophyll-a, and if present, can interfere with acquiring an accurate chlorophyll-a value. The ratio of chlorophyll-a to phaeophytin-a has been used as an indicator of the physiological condition of phytoplankton in the sample.

2019 Productivity Data

In 2019, the chlorophyll-a concentration: • mean 5.0 µg/L • median 4.0 µg/L

The mean chlorophyll-a concentration was almost three times higher during the second half of the sampling season: • 7.4 µg/L from August to October • 2.6 µg/L from May to July Figure 8 shows that the highest productivity occurred in October (9.8 µg/L) after turn-over. The ratio of chlorophyll-a to phaeophytin-a peaked in August and June, indicating a breakdown of chlorophyll-a during those two months.

Hicks Lake - 2019 Chlorophyll-a, Ratio Chlorophyll-a to Phaeophytin-a, and DO 12 10 9 10 8 7 8 6 µg/L)

a ( 6 5 -

4 µg/L) and DO (mg/L)

4 a ( 3 - 2 Chlorophyll 2 1 0 0 Phaeophytin May June July August September October

Chlorophyll-a Ratio Chlor-a : Phaeo-a Surface DO

Figure 8. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments and mean DO in the epilimnion at HK1 in 2019.

Hicks Lake 2019 Phytoplankton Identification

Appendix B provides a list phytoplankton collected from the epilimnion at HK1 during 2019 sample events from Hicks Lake. The dominant genus at the beginning of summer (May and June) and again in September (after phaeophytin-a peaked) was Dinobryon sp., a type of golden algae or chrysophyte. These species are mixotrophic; they can consume bacteria (phagotrophy) or use photosynthesis to produce energy. Spores rested on the bottom of Hicks Lake over winter. Increased sunlight in the spring induce germination of motile cells, which move to the surface to proliferate.

In July, the dominant taxon was Phormidium sp., a type of cyanobacteria (blue-green algae). Phorm (Greek) means basket or mat, which describes the its typical colonial form. This cyanobacteria forms mats of intertwined filaments on aquatic substrates. Phormidium sp can produce neurotoxic anatoxins.

In August, another genus of cyanobacteria, Chroococcus sp., dominated the phytoplankton community: This type of cyanobacteria occurs as cells or groups of cells surrounded by a mucilaginous envelop.

In October, the dominate taxon was Asterionella sp., a diatom that frequently occurs in star-shaped colonies of cells. Diatoms are unicellular algae with silicon dioxide cell wall. Diatoms (the name means split into two) are named for the two-part opaline silica wall, or frustrule. Asterionella sp. are common in spring, summer, and fall blooms. One particular buoyant species has the slowest known sinking rate of freshwater diatoms (Reynolds, 1984). Asterionella is considered a clean water genus.

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998) Figure 9 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at HK1. Hicks Lake has been phosphorus limited since 1995.

Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 9 shows the TN to TP ratio in 2019 and from 1996 to 2019. Hicks Lake is phosphorus limited.

Hicks Lake 2019

Figure 8. TP, TN, and TN:TP at the surface of Hicks Lake in 2019 and TN:TP from 1996 to 2019.

The concentration of TN in surface waters was highest in July, when the lake was stratified. The concentration of TP began to climb when mixing began in September and peaked after turnover in October. Thermal stratification reduced internal loading to surface waters from May to August; changes in the phytoplankton community and external sources likely affect nutrient levels during stratification.

Total Phosphorus

The monthly TP results are displayed in Figure 10. The 2019 statistics are: • Surface Mean 0.016 mg/L • Bottom Mean 0.176 mg/L • Surface Median 0.012mg/L • Bottom Median 0.185 mg/L • Surface Standard Deviation 0.006 mg/L • Bottom Standard Deviation 0.063 mg/L

Hicks Lake 2019 Hicks Lake - 2019 Total Phosphorus

0.32 0.28 0.24 0.20 0.16

mg/L 0.12 Action Level 0.08 0.02 mg/L 0.04 0.00 May June July August September October Surface TP Bottom TP

Figure 9. TP at the surface and bottom at HK1 in 2019.

The vertical profile graphs show that Hicks Lake exhibited a clinograde oxygen curve from May until September. Water in the hypolimnion was not mixing with the warmer, oxygenated water above. Decomposition and redox processes consumed oxygen in the hypolimnion: DO was 0.5 to 0.6 mg/L from June to September. Due to the lack of oxygen, phosphorus stored in the sediments was released into the water column and accumulated in the hypolimnion, peaking in September. The concentration of TP at the bottom was sharply reduced when the water column mixed in October.

Figure 11 displays the average annual concentration of TP at HK1 from 1995 to 2019. The mean annual surface TP was above the state action level (purple line at 0.020 mg/L) twice, in 1999 and 2001.

Hicks Lake - Total Phosphorus Annual Summer Averages 0.32

0.28

0.24

0.20

0.16 mg/L

0.12

0.08 Action Level 0.02 mg/L 0.04

0.00 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TP

Figure 10. Mean concentration of TP at the surface and bottom at HK1 from 1995 to 2019.

Hicks Lake 2019 From 1995 to 2019, the TP statistics are: • Mean Surface 0.016 mg/L • Mean Bottom 0.162 mg/L • Median Surface 0.016 mg/L • Median Bottom 0.160 mg/L • Standard Deviation Surface 0.003 mg/L • Standard Deviation Bottom 0.047 mg/L • Maximum Surface 0.022 mg/L in 1999 • Maximum Bottom 0.297 mg/L in 2015 • Minimum Surface 0.012 mg/L in 1996 • Minimum Bottom 0.079 mg/L in 2008

Nitrogen

The TN statistics for 2019 are: • Surface Mean 0.394 mg/L • Bottom Mean 0.832 mg/L • Surface Median 0.398 mg/L • Bottom Median 0.815 mg/L • Surface Standard Deviation 0.075 mg/L • Bottom Standard Deviation 0.245 mg/L

In anoxic conditions, ammonia-nitrogen is released from the bottom sediments and accumulates in the hypolimnion, particularly at the end of the season in September (Figure 12). Nitrogen was highest at the surface in July when chlorophyll-a concentration was lowest. For the long-term nitrogen data, see Figures 13.

Hicks Lake - 2019 Total Nitrogen 1.4 1.2 1.0 0.8 0.6 mg/L 0.4 0.2 0.0 May June July August September October Surface TN Bottom TN

Figure 11. Concentration of TN at the surface and bottom at HK1 in 2019.

Hicks Lake 2019 Hicks Lake at HK1 - TN Annual Summer Averages 2.50

2.00

1.50

mg/L 1.00

0.50

0.00 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN Bottom TN

Figure 12. Average Annual Summer TN at HK1 from 1995 to 2018.

The TN statistics from 1995 to 2019 are: • Mean Surface 0.453 mg/L • Mean Bottom 0.988 mg/L • Median Surface 0.468 mg/L • Median Bottom 0.940 mg/L • Standard Deviation Surface 0.052 mg/L • Standard Deviation Bottom 0.342 mg/L • Maximum Surface 0.531 mg/L in 2001 • Maximum Bottom 2.007 mg/L in 1995 • Minimum Surface 0.349 mg/L in 2005 • Minimum Bottom 0.600 mg/L in 2005

Trophic State Indices (TSI)

The most used method to classify lakes is called the Carlson’s Trophic State Index (Carlson, 1977). Based on the productivity, this method uses three index variables: transparency (secchi disk depth), chlorophyll-a, and phosphorus concentrations. Table 3 provides the index values for each trophic classification. Table 3. Trophic State Index variables TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

The TSI calculated from the 2019 results are: • Secchi Disk: 44 mesotrophic • Chlorophyll-a: 46 mesotrophic • Total Phosphorus: 44 mesotrophic

The average of the three TSI variables is 45, which categorizes Hicks Lake as mesotrophic in 2019, which is how it was classified in 1981 by the USGS. (Figure 14).

Hicks Lake 2019

Hicks Lake TSI Scores 1995 to 2019 60 Eutrophic 55

45 Mesotrophic

35 Maen TSI Score Oligotrophic 30

20 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Chl-a Surface TP Secchi

Figure 13. Hicks Lake Mean Trophic State Index scores from 1995 to 2019. From 1995 to 2019, 70% of the TSI scores for chlorophyll-a and 30% for Secchi depth indicate eutrophic conditions. However, the seasonal Kendall test (Thurston County Environmental Health, 2018) indicate that the chlorophyll-a concentration had a significant (p < 0.05) decreasing trend from 2007 to 2018 for June, July, August, and September.

Hicks Lake 2019 SUMMARY

Thermal Stratification In 2019, the water column at Hicks Lake was thermally stratified into three distinct layers from May to September. In October, Hicks Lake was turning over.

Higher than Average Transparency In 2019, transparency (mean and median 3.1 meters) was higher than the long-term average. Transparency was greater from May to July, when the chlorophyll-a concentration was lower. Transparency declined later in the summer as productivity increased from August until turnover in October.

Greater Productivity Late Summer The chlorophyll-a concentration (season mean 5.0, median 4.0 µg/L) was higher from August to October (mean 7.4 µg/L). Cyanobacteria dominated the phytoplankton community in July and August. A type of golden algae was abundant early in the summer and again in September. In October, as Hicks Lake began to turnover, the chlorophyll-a concentration and abundance of the diatom Asterionella sp. peaked. Diatoms tend to increase in response to mixing during fall turnover. Asterionella is considered a clean water genus.

Nutrient Concentrations TP peaked at the lake bottom in September. At the surface, TP peaked in October after fall turn over mixed the water column. In 2019, the mean surface TP was 0.016 mg/L, which is the same as the long- term (1995 to 2019) mean and median. The surface TP concentration has not been above the action level (0.020 mg/L) since 2001.

In May, at the start of the summer, surface TN was at the season’s low point. The concentration grew greater until August. After productivity increased in August, the TN surface concentration declined each successive month. Internal loading did not increase TN at the surface in October. The surface and bottom TN concentrations were less than the long-term (1995 to 2019) mean and medians.

Seasonal Kendall analysis (Thurston County Environmental Health, 2018) revealed significant (p < 0.05) downward trends of both surface TP and TN concentrations from 2007 to 2018. For surface TP, the downward trends existed during May, August, and September. TP trended upward in October, likely due to mixing of the water column after turnover. Surface TN trended down in May and September and up in July.

Classified as Mesotrophic Hicks Lake was classified as mesotrophic in 2019 based on an average of the three TSI variables.

Hicks Lake 2019 DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 or https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 or https://www.co.thurston.wa.us/health/ehrp/annualreport.html For digital data contact: [email protected] For correction, questions, and suggestions, contact the author of the 2019 report: [email protected]

FUNDING SOURCE:

City of Lacey funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

Reynolds, C.S. 1984. The ecology of freshwater phytoplankton. Cambridge University Press, Cambridge, UK, 384 pp.

Thurston County Environmental Health. 2018. Hicks Lake Water Quality Report. https://www.co.thurston.wa.us/health/ehrp/annualreport.html

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

Hicks Lake 2019

Appendices

Appendix A. Raw Data Appendix B. Algae and Cyanobacteria Identification Appendix C. Quality Assurance/Quality Control

Appendix A. Raw data

Profile Samples Site INFO Temp ( C ) pH DO (m/l) Sp Cond TP TN Composite Sample Bottom Bottom Total Secchi Water Profile Sample Site Date Time Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a (m) Color Depth Depth (m) (m) (m) Hicks - HK1 5/20/2019 15:36 10.4 3.85 3 9.5 18.524 6.992 8.10 6.62 9.48 0.88 58.4 66.4 9.5 0.012 0.131 0.264 0.511 3.2 1.1 Hicks - HK1 6/18/2019 9:31 10.45 3.80 4 10.0 21.535 7.487 7.59 6.36 9.11 0.52 103.3 81.2 9.9 0.011 0.192 0.416 0.922 2.5 0.5 Hicks - HK1 7/25/2019 12:06 9.4 3.25 7 9.0 22.840 8.524 7.34 6.42 8.48 0.47 61.3 87.7 9 0.012 0.179 0.519 0.950 2.0 0.7 Hicks - HK1 8/28/2019 9:03 9.05 2.50 3 8.5 22.231 9.545 7.53 6.27 9.12 0.47 62.8 91.5 8.5 0.012 0.190 0.407 0.707 7.7 1.2 Hicks - HK1 9/25/2019 9:22 9.4 2.45 6 8.5 18.370 10.201 6.93 6.28 7.94 0.57 63.0 100.1 9.00 0.020 0.284 0.388 1.260 4.8 1.9 Hicks - HK1 10/23/2019 9:40 9.4 2.95 7 9.0 12.752 12.460 7.55 6.54 9.48 6.85 62.8 66.2 9.00 0.027 0.078 0.369 0.639 9.8 3.5

Hicks Lake 2019

Appendix B. Phytoplankton Identification

Project: 421874-991 Project: 421874-991 Project: 421874-991 Locator: NONE Locator: NONE Locator: NONE Sample: L72426-1 Sample: L72614-1 Sample: L72896-1 Matrix: LK FRESH WTR Matrix: LK FRESH WTR Matrix: LK FRESH WTR ColDate: 5/20/19 15:35 ColDate: 6/18/19 9:41 ColDate: 7/25/19 12:21 ClientLoc: Lake Hicks ClientLoc: Lake Hicks ClientLoc: Lake Hicks WET Weight Basis WET Weight Basis WET Weight Basis

Parameters Value Qual MDL RDL Units Value Qual MDL RDL Units Value Qual MDL RDL Units MC PRESCOTT 1954 Achnanthidium sp. P none Ankistrodesmus sp. Aphanizomenon sp. Aphanocapsa sp. S none Arthrodesmus sp. Asterionella sp. P none P none Aulacoseira sp. P none P none P none Ceratium sp. S none Chroococcus sp. Closterium sp. P none Cocconeis sp. Cosmarium sp. P none P none Crucigenia sp. P none Cryptomonas sp. P none Cyclotella sp. P none P none Dictyosphaerium sp. P none Dinobryon sp. D none D none Dolichospermum sp. - irregularly twisted P none P none Dolichospermum sp. - straight P none Elakatothrix sp. Epithemia sp. Eudorina sp. P none P none Euglena sp. Eunotia sp. Few algae seen on microscopic exam P none Fragilaria sp. P none Gomphonema sp. P none Mallomonas sp. Microcystis sp. Navicula sp. P none Nitzschia sp. P none Oocystis sp. P none P none Pediastrum sp. P none Peridinium sp. P none Phormidium sp. D none Planktosphaeria sp. P none P none P none Planktothrix sp. Quadrigula sp. P none Rhodomonas sp. P none Scenedesmus sp. P none Snowella sp. Staurastrum sp. P none Stephanodiscus sp. S none Synedra sp. P none Tabellaria sp. P none P none Tetraedon sp. P none Trachelomonas sp. P none Undetermined Diatom: Pennate P none Undetermined Dinophyceae P none Undetermined Spherical: 4-7 microns Woronichinia sp. P none

D = Dominant P = Present S = Subdominant

Hicks Lake 2019

Project: 421874-991 Project: 421874-991 Project: 421874-991

Locator: NONE Locator: NONE Locator: NONE

Sample: L73183-1 Sample: L73361-1 Sample: L73573-1

Matrix: LK FRESH WTR Matrix: LK FRESH WTR Matrix: LK FRESH WTR

ColDate: 8/28/19 9:20 ColDate: 9/25/19 9:34 ColDate: 10/25/19 0:00

ClientLoc: Lake Hicks ClientLoc: Lake Hicks ClientLoc: Lake Hicks

WET Weight Basis WET Weight Basis WET Weight Basis

Parameters Value Qual MDL RDL Units Value Qual MDL RDL Units Value Qual MDL RDL Units

MC PRESCOTT 1954

Achnanthidium sp.

Ankistrodesmus sp. P none P none P none

Aphanizomenon sp. P none P none P none

Aphanocapsa sp. P none S none P none

Arthrodesmus sp. P none

Asterionella sp. P none D none

Aulacoseira sp. P none P none P none

Ceratium sp. P none P none

Chroococcus sp. D none P none

Closterium sp. P none P none

Cocconeis sp. P none

Cosmarium sp. P none P none

Crucigenia sp. P none

Cryptomonas sp. P none

Cyclotella sp. P none P none P none

Dictyosphaerium sp. P none P none P none

Dinobryon sp. D none S none

Dolichospermum sp. - irregularly twisted P none P none

Dolichospermum sp. - straight S none P none

Elakatothrix sp. P none

Epithemia sp. P none

Eudorina sp. P none

Euglena sp. P none

Eunotia sp. P none

Few algae seen on microscopic exam

Fragilaria sp. P none P none

Gomphonema sp.

Mallomonas sp. P none P none

Microcystis sp. P none

Navicula sp. P none

Nitzschia sp. P none P none

Oocystis sp. P none

Pediastrum sp. P none

Peridinium sp.

Phormidium sp.

Planktosphaeria sp.

Planktothrix sp. P none P none

Quadrigula sp. P none P none P none

Rhodomonas sp. P none P none

Scenedesmus sp. P none P none

Snowella sp. P none P none

Staurastrum sp. P none P none P none

Stephanodiscus sp. P none

Synedra sp. P none P none

Tabellaria sp. P none P none

Tetraedon sp. P none

Trachelomonas sp. P none P none P none

Undetermined Diatom: Pennate

Undetermined Dinophyceae P none

Undetermined Spherical: 4-7 microns P none

Woronichinia sp.

D = Dominant

P = Present S = Subdominant

Hicks Lake 2019

Appendix C. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

Hicks Lake 2019

2019 Lake Lawrence Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Lake Lawrence map showing location of sample sites LL1 and LL2.

DESCHUTES RIVER WATERSHED lakeside residents have three private access points. • SHORELINE LENGTH: 4.0 miles • LAKE SIZE: 0.52 square miles (330 acres) GENERAL TOPOGRAPHY: • BASIN SIZE: 3.35 square miles Lake Lawrence is north of the Bald Hills, at an • MEAN DEPTH: 4.0 meters (13 feet) elevation of approximately 421 feet above • MAXIMUM DEPTH: 7.9 meters (26 feet) mean sea level. The lake, which is very close to • VOLUME: 4,617 acre-feet the Deschutes River, normally discharges to the river via a small stream. During extreme PRIMARY LAND USES: flooding events, the river water backs up into Land use is primarily rural with some the lake. agriculture and undeveloped forest land. GENERAL WATER QUALITY: PRIMARY LAKE USES: Fair – Lake Lawrence is eutrophic. Water Lake Lawrence is used for fishing, boating, quality is impaired by excessive nutrients. swimming and other water sports. Harmful algal blooms have produced biotoxins that can cause illness. Algal blooms also reduce PUBLIC ACCESS: transparency, which can interfere with water Washington Department of Fish and Wildlife recreation. operate one public boat launch. Also, the Lake Lawrence 2019 DESCRIPTION

Lake Lawrence is in the Deschutes River Watershed, approximately six miles south of Yelm and six miles southeast of Rainier, Washington. The lake has two distinct basins, a large basin on the east side (site LL1) and a smaller basin to the west (site LL2). Lake Lawrence is fed by groundwater; no surface water inlet exists. A small outlet channel discharges out of the west basin through a control structure across the floodplain to the Deschutes River. The lake is relatively shallow, with an average depth of approximately 4 meters (13 feet).

Unfortunately, numerous harmful algal blooms have occurred at Lake Lawrence. Thurston County Environmental Health (TCEH) collected sixteen algae samples with microcystin toxin that exceeded the advisory level in 2009, 2010, 2013, 2015, 2017, 2018, and 2019.

Aquatic macrophyte and algae growth at Lake Lawrence is exacerbated by shallow water, high nutrient levels, warmer weather, and fluctuations in lake levels (TCPW, 2018). Since 1986, an active lake management district (LMD), has funded aquatic weed control and fisheries management activities. In the early 1990s, a state grant and community supported LMD funded a lake restoration study.

METHODS

In 2019, TCEH conducted monthly monitoring at two sites from May to October. Site LL1 is in the deepest part of the larger eastern basin (Figure 1). LL2 is at the deepest part of the smaller western basin. Table 1 lists the types of data collected (Thurston County, 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.

2 Lake Lawrence 2019

Figure 2. TCEH compared color of the lake’s water to the Custer Color Strip.

Quality Assurance and Quality Control (QA/QC)

TCEH collected 15% field replicates and field blanks for TP, TN, chlorophyll-a, and phaeophytin-a samples in 2019. Field replicates (or duplicates) were collected to determine sampling and laboratory precision. Field blanks provide information about possible errors or contamination during collection and analysis. The calibration of the Yellow Springs Instrument (YSI) EXO1 was verified before and after each sampling day. See Appendix B for all 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. Monthly Weather Month Weather on Sample Day Temperature (°C) Mean (Low/High) May Partly cloudy (21°C); 0-3 mph Variable wind 13 (2/30) June Partly cloudy (19°C); 14-18 mph WNW wind (Gusts 25 mph) 15 (4/33) July Mostly cloudy (22°C); 0-5 mph SW wind 18 (8/32) August Fair (27°C); 0-13 mph N/NE wind (Gusts 21 mph) 18 (7/33) September Partly cloudy (20°C); 0-9 mph W wind 14 (-1/26) October Mostly cloudy (16°C); 0-9 mph WNW wind 8 (-6/18)

Vertical Water Quality Profiles

The vertical water quality profiles illustrate how the water column at Lake Lawrence was thermally stratified in mid-summer (Figures 3 to 8). Warmer, more oxygenated water existed on the surface in the epilimnion. Below this layer, the temperature and oxygen concentration declined with depth. The shallower site (LL2) showed signs of mixing in August. The process of turn-over was evident at both sites in September.

3 Lake Lawrence 2019 LL1 Lake - May 22, 2019 LL2 Lake - May 22, 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 Depth (meters)

Depth (meters) 4 4

5 5

6 6 0 50 100 150 200 250 0 50 100 150 200 250 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 3. Vertical water quality profiles for LL1 and LL2 collected during May 2019.

In May, surface of the lake was warming. The temperature difference between the epilimnion (Epi) and hypolimnion (Hypo) was greater at LL2: Transparency was greater than 1.5 meters at both sites in May. DO and pH were greatest from 1.5 to 3.5 meters depth, indicating photosynthesis was occurring in deeper water. • LL1 Epi 17.8°C; DO 10.2 mg/L; pH 8.5 • LL2 Epi 17.9°C; DO 11.5 mg/L; pH 9.0 • LL1 Hypo 14.0°C; DO 0.6 mg/L; pH 6.8 • LL2 Hypo 11.7°C; DO 0.6 mg/L; pH 6.8

LL1 - June 19, 2019 LL2 - June 19, 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 Depth (meters) Depth (meters)

5 5

6 6 0 50 100 150 200 250 0 50 100 150 200 250 SPC µS/cm SPC µS/cm

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 4. Vertical water quality profiles for LL1 and LL2 collected during June 2019.

In June, the warm surface layer extended to 3.5 meters depth at both sites and the effects of thermal stratification became more readily apparent. At both sites, the temperature difference between the epilimnion and hypolimnion increased and the DO curve was clinograde. • LL1 Epi 20.8°C; DO 9.5 mg/L; pH 8.8 • LL2 Epi 20.9°C; DO 9.6 mg/L; pH 8.9 • LL1 Hypo 15.4 °C; DO 0.6 mg/L; pH 6.8 • LL2 Hypo 14.5°C; DO 0.5 mg/L; pH 6.

4 Lake Lawrence 2019

LL1 - July 24, 2019 LL2 - July 24, 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 Depth (meters) Depth (meters)

5 5

6 6 0 50 100 150 200 250 0 50 100 150 200 250 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 5. Vertical water quality profiles for LL1 and LL2 collected during July 2019.

In July, the epilimnion remained 3.5 meters deep. The temperature difference between the surface and bottom was less than the difference in June. • LL1 Epi 22.4°C; DO 9.0 mg/L; pH 8.1 • LL2 Epi 22.8°C; DO 9.7 mg/L; pH 8.6 • LL1 Hypo 17.6°C; DO 0.6 mg/L; pH 6.8 • LL2 Hypo 18.8°C; DO 0.5 mg/L; pH 6.7

LL1 - August 27, 2019 LL2 - August 27, 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 0

1.0 1

2.0 2

3.0 3

4.0 Depth (meters) 4 Depth (meters)

5.0 5

6.0 6 0 50 100 150 200 250 0 50 100 150 200 250 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 6. Vertical water quality profiles for LL1 and LL2 collected during August 2019.

In August, the difference between the epilimnion and hypolimnion temperatures at both sites was less than in July. Nutrient concentrations indicate LL2, the shallower site, was mixing to greater depths in August compared to LL1. • LL1 Epi 22.0°C; DO 9.6 mg/L; pH 8.4 • LL2 Epi 22.3°C; DO 9.9 mg/L; pH 8.5 • LL1 Hypo 20.2°C; DO 0.6 mg/L; pH 6.7 • LL2 Hypo 19.6°C; DO 0.5 mg/L; pH 6.6 5 Lake Lawrence 2019 LL1 - September 24, 2019 LL2 - September 24, 2019 Temperature (°C), pH, DO (mg/L) Temperature (°C), pH, DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0

1 1

2 2

3 3 Depth (meters) Depth (meters) 4 4

5 5

6 6 0 50 100 150 0 50 100 150 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 7. Vertical water quality profiles from LL1 and LL2 collected during September 2019.

In September, air temperatures dropped, particularly after sunset. Surface waters cooled and sank, causing the water columns to mix. Turn-over was occurring at both sites. The differences in temperature, DO, and pH at the surface and the bottom were much smaller than in August. • LL1 Photic 18.9°C; DO 10.5 mg/L; pH 8.4 • LL2 Photic 18.9°C; DO 9.8 mg/L; pH 8.1 • LL1 Bottom 18.3°C; DO 8.1 mg/L; pH 7.5 • LL2 Bottom Temp. 18.2°C; DO 8.2 mg/L; pH 7.4

LL1 - October 22, 2019 LL2 - October 22, 2019

Temperature (°C), pH (std), DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0

1 1

2 2

3 3

4 Depth (meters) Depth (meters) 4

5 5

6 6 0 50 100 150 0 50 100 150 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 8. Vertical water quality profiles from LL1 and LL2 collected during October 2019.

In October, the water quality at the surface and bottom of the lake were nearly homogeneous. • LL1 Photic 13.0°C; DO 11.3 mg/L; pH 8.7 • LL2 Photic 13.5°C; DO 11.9 mg/L; pH 8.8 • LL1 Bottom 12.6°C; DO 10.5 mg/L; pH 8.5 • LL2 Bottom 12.8°C; DO 11.1 mg/L; pH 8.5

6 Lake Lawrence 2019 Color and Transparency

Color can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. High concentrations of algae cause the color of the water to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown. Color of the lake’s water was recorded as #3 every month at both sites, except at LL2 in June when the color was #6 and July when the color was #7 (Figure 9).

Figure 9. Secchi depth, Custer Strip color, and chlorophyll-a concentration at LL1 and LL2 in 2019. Transparency was greatest in May and July at LL1 and May and June at LL2. At both sites, transparency declined each successive month from August to October. Transparency was negatively correlated to chlorophyll-a concentration at LL2 (R²=0.87). At LL1, the relationship between transparency and chlorophyll-a was much weaker (R²=0.48). The mean/median Secchi depth was 1.4/1.3 meters at LL1 and 1.4 meters at LL2.

Figure 10 shows the annual average transparency (Secchi depth) compared to the long-term average. Positive values reflect transparency better than the long-term average. In 2019, transparency at both sites was less than the long-term average: 1.0 meter lower at LL1 and 0.8 meter lower at LL2. The Seasonal Kendall test revealed a trend of reduced transparency for two-thirds of the sample season at both sites from 2009 to 2018 (TCEH, 2018). The downward trend in transparency continued in the 2019 sample season.

7 Lake Lawrence 2019

Transparency (meters) Annual Average Minus Long-Term Average

1.00

0.50

LTA LL1 0.002.36m

LL2 2.17m meters

-0.50

-1.00

-1.50

LL1 LL2

Figure 10. Transparency at LL1 and LL2 compared to the long-term average (LTA). Pigments

Phaeophytin absorbs light in the same region of the spectrum as chlorophyll-a, and, if present can interfere with acquiring an accurate chlorophyll-a value. Phaeopigments have been reported to contribute 16 to 60% of the measured chlorophyll-a content (Marker et al., 1980).

2019 Productivity Data

Figure 11 shows that the concentration of DO and chlorophyll-a was lower in June and July at both sites. Starting in August, chlorophyll-a levels increased each successive month. The concentration of DO and chlorophyll-a in the epilimnion peaked in October. At LL2, the concentration of chlorophyll-a was also high in May. The ratio of chlorophyll-a to phaeophytin-a peaked in May at both sites. The test for trends (TCEH, 2018) in chlorophyll-a for 2009 to 2018 indicated a significant (p<0.05) increase in chlorophyll-a: • The greatest positive trend (6 µg/L) occurred at LL1 in October • In August both sites had modest increases (2 to 3 µg/L) over the last decade • In May, LL1 had a smaller increase (0.3 µg/L)

8 Lake Lawrence 2019

Figure 11. Chlorophyll-a concentration, the ratio of chlorophyll-a to phaeophytin-a pigments, and DO in the epilimnion at LL1 and LL2 in 2019.

TCEH sampled algae nine times at Lake Lawrence from August to November 2019. Two samples tested positive for the biotoxin microcystin in mid-October (Appendix C). This toxin is a potent cellular inhibiting protein-phosphatase, which cause hepatocyte necrosis and hemorrhaging into liver tissues of mammals and other vertebrates, including fish. The toxin is produced by the cyanobacteria of the same name, Microcystis. Some Microcystis have complex life histories: overwintering at the lake’s bottom and rising to the surface with gas vacuoles during the warm summer months.

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Carrell, 1998). Figures 12 and 13 shows the concentration of TP and TN at the two Lake Lawrence sites.

At LL1 in September, the epilimnion concentration of TP increased 54% and TN increased 37%. At LL2, the concentration of TP in the epilimnion increased 29% in August.

9 Lake Lawrence 2019

Figure 12. Concentration of TP and TN at LL1 in 2019.

Figure 13. Concentration of TP and TN at LL2 in 2019

10 Lake Lawrence 2019 Total Phosphorus

The surface TP concentration (mg/L) was above the action level for the duration of the 2019 sample season: • LL1 Surface Mean 0.058 • LL2 Surface Mean 0.058 • LL1 Surface Median 0.050 • LL2 Surface Median 0.058 • LL1 Surface Std Dev 0.026 • LL2 Surface Std Dev 0.015 • LL1 Surface Minimum 0.036 in July • LL2 Surface Minimum 0.034 in May • LL1 Surface Maximum 0.105 in Sept • LL2 Surface Maximum 0.073 in Oct

In 2019, the concentration of TP (mg/L) near the bottom was: • LL1 Bottom Mean 0.321 • LL2 Bottom Mean 0.153 • LL1 Bottom Median 0.176 • LL2 Bottom Median 0.180 • LL1 Bottom Std Dev 0.336 • LL2 Bottom Std Dev 0.050 • LL1 Bottom Minimum 0.070 in Oct • LL2 Bottom Minimum 0.071 in Sept • LL1 Bottom Maximum 0.927 in June • LL2 Bottom Maximum 0.189 in June

The vertical profile graphs show that LL1 exhibited a clinograde oxygen curve from June until August. At LL2, the DO curve was clinograde in June and July, with some mixing evident in August. During thermal stratification, water density differences prevented the hypolimnion from mixing with upper strata. In the stagnant hypolimnion, decomposition and other redox processes consumed the oxygen supply. Phosphorus stored in the sediments was released into the water column and accumulated in the hypolimnion until the deeper water mixed with the rest of the water column.

TP data from 2008 to 2018 was analyzed using the Seasonal Kendall test (TCEH, 2018). This analysis revealed significant trends of increasing TP concentration in surface water at LL1 from July to August (0.001 to 0.002 mg/L) and in October (0.016 mg/L). At LL2, the trend was increasing TP from May to July (0.002 to 0.004 mg/L) and in October (0.007 mg/L).

Total Nitrogen

In 2019, the surface TN concentration (mg/L) was: • LL1 Surface Mean 1.171 • LL2 Surface Mean 0.869 • LL1 Surface Median 1.110 • LL2 Surface Median 0.974 • LL1 Surface Std Dev 0.373 • LL2 Surface Std Dev 0.390 • LL1 Surface Minimum 0.733 in May • LL2 Surface Minimum 0.164 in Oct • LL1 Surface Maximum 1.660 in Oct • LL2 Surface Maximum 1.260 in July

11 Lake Lawrence 2019 During stratification, the hypolimnion was anoxic. Ammonia-nitrogen was released from the bottom sediments and accumulated in the hypolimnion. Nitrogen compounds from the hypolimnion mixed with surface waters after turnover in September and October. The turnover process started earlier at LL2. Thermal stratification was weaker in the shallower basin.

The concentration of TN (mg/L) near the bottom in 2019 was: • LL1 Bottom Mean 1.620 • LL2 Bottom Mean 1.745 • LL1 Bottom Median 1.825 • LL2 Bottom Median 1.750 • LL1 Bottom Std Dev 0.447 • LL2 Bottom Std Dev 0.300 • LL1 Bottom Minimum 0.990 in May • LL2 Bottom Minimum 1.300 in Sept • LL1 Bottom Maximum 2.040 in Aug • LL2 Bottom Maximum 2.170 in Aug

The Seasonal Kendall test (TCEH, 2018) showed a significant (p<0.05) upward trend of surface TN concentrations at both sites. In general, TN increased each month from May until October, except for a larger increase in September at LL2. No significant trend was detected at LL1 in September (n=9) and at LL2 in June.

Historical Nutrient Data: Total Phosphorus

The bottom TP reached the maximum for the period of record (1998 and 2009 to 2019) in 2019. For the period of record, the TP concentration (mg/L) at LL1 was: • LL1 Surface Mean 0.037 • LL1 Bottom Mean 0.093 • LL1 Surface Median 0.027 • LL1 Bottom Median 0.053 • LL1 Surface Std Dev 0.021 • LL1 Bottom Std Dev 0.087 • LL1 Surface Minimum 0.019 in 2013 • LL1 Bottom Minimum 0.035 in 2012 • LL1 Surface Maximum 0.084 in 2016 • LL1 Bottom Maximum 0.321 in 2019

Figure 14 displays the annual mean TP concentration at LL1 in 1998 and from 2009 to 2019. The surface samples for TP have been above the state action level (dotted purple line at 0.020 mg/L) for 92% of the period of record, every year except 2013.

LL1 - TP Annual Means 0.35

0.30

0.25

0.20 Action 0.15 Level mg/L 0.020 0.10 mg/L

0.05

0.00 1998 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TP Bottom TP

Figure 14. Average Annual Total Phosphorus at LL1 from 1998 and 2009 to 2019.

12 Lake Lawrence 2019 Figure 15 shows the annual mean TP at LL2, the west basin site. The TP concentration has exceeded the state action level every sample season since 2009. The maximum surface TP concentration at LL2 occurred in 2019.

LL2 - TP Annual Means 0.35

0.30

0.25

0.20

0.15 Action

mg/L Level 0.020 0.10 mg/L

0.05

0.00 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TP Bottom TP

Figure 15. Average Annual Total Phosphorus at LL2 from 2009 to 2019. For the period of record (2009 to 2019), the TP concentration (mg/L) at LL2 was: • LL2 Surface Mean 0.033 • LL2 Bottom Mean 0.107 • LL2 Surface Median 0.030 • LL2 Bottom Median 0.071 • LL2 Surface Std Dev 0.010 • LL2 Bottom Std Dev 0.081 • LL2 Surface Minimum 0.022 in 2013 • LL2 Bottom Minimum 0.045 in 2015 • LL2 Surface Maximum 0.058 in 2019 • LL2 Bottom Maximum 0.330 in 2017

Historical Nutrient Data: Total Nitrogen

Figure 16 displays the mean annual concentration for total TN in 1998 and from 2009 to 2019 at LL1. The last time the LL1 mean surface concentration was below 0.60 mg/L was in 2016. The TN concentration has increased each year since 2016, at both the surface and bottom.

13 Lake Lawrence 2019

LL1 - TN Annual Means 1.80 1.60 1.40 1.20 1.00

mg/L 0.80 0.60 0.40 0.20 0.00 1998 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TN Bottom TN

Figure 16. Average Annual Total Nitrogen at LL1 from 1998 and 2009 to 2019.

For the period of record at LL1, the TN concentration (mg/L) was: • LL1 Surface Mean 0.684 • LL1 Bottom Mean 0.861 • LL1 Surface Median 0.607 • LL1 Bottom Median 0.703 • LL1 Surface Std Dev 0.226 • LL1 Bottom Std Dev 0.367 • LL1 Surface Minimum 0.465 in 1998 • LL1 Bottom Minimum 0.519 in 1998 • LL1 Surface Maximum 1.171 in 2019 • LL1 Bottom Maximum 1.620 in 2019

Figure 17 shows the mean annual TN concentration at LL2 from 2009 to 2019. The maximum concentration at the surface occurred in 2018 and at the bottom in 2019.

LL2 - TN Annual Summer Averages 2.00 1.80 1.60 1.40 1.20 1.00 mg/L 0.80 0.60 0.40 0.20 0.00 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN

Figure 17. Average Annual Total Nitrogen at LL2 from 2009 to 2019.

14 Lake Lawrence 2019

For the last decade, the TN concentration (mg/L) was: • LL2 Surface Mean 0.697 • LL2 Bottom Mean 0.941 • LL2 Surface Median 0.654 • LL2 Bottom Median 0.791 • LL2 Surface Std Dev 0.175 • LL2 Bottom Std Dev 0.384 • LL2 Surface Minimum 0.492 in 2011 • LL2 Bottom Minimum 0.549 in 2012 • LL2 Surface Maximum 1.020 in 2018 • LL2 Bottom Maximum 1.745 in 2019

Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 18 shows the TN to TP ratio of surface waters at the two Lake Lawrence sites. LL1 was nitrogen limited in 2016 and 2017.

TN to TP Ratio 50

40 Phosphorus Limited

10 TN:TP (mg/L) Nitrogen Limited 0 1998 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

LL1 LL2

Figure 18. TN:TP at LL1 from 1998 and 2009 to 2019 and LL2 from 2009 to 2019.

Trophic State Indices (TSI)

15 Lake Lawrence 2019

For LL1, the 2019 TSI results were: • Chlorophyll-a: 64 eutrophic • Total Phosphorus: 63 eutrophic • Secchi Disk: 55 eutrophic

The average of the three TSI variables is 61, which categorizes LL1 as eutrophic in 2019. Based on the concentration of chlorophyll-a, LL1 was classified as eutrophic every year that data was collected (Figure 19). For the period of record, TP enrichment classified LL1 as eutrophic three-quarters of the twelve sample seasons. Secchi measurements resulted in a eutrophic classification less often: • 25% of sample seasons eutrophic due to low transparency

LL1 Trophic State Indices 70 65 60

55 Eutrophic 50 45 Mesotrophic

TSI Score 40 35 Oligotrophic 30 25 20 1998 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Chlorophyll-a TSI TP TSI TSI (Secchi)

Figure 19. LL1 Trophic State Index from 1998 and 2009 to 2019. The Mann Kendall test revealed a significant trend (p˂0.05) of increasing TSI values for all three parameters at LL1; the trend from 2009 to 2018 was toward eutrophication, with higher productivity, increased TP concentrations, and reduced water clarity (TCEH, 2018).

The TSI results for the west basin site LL2 were: • Chlorophyll-a: 64 eutrophic • Total Phosphorus: 63 eutrophic • Secchi Disk: 56 eutrophic

The average TSI score for LL2 was 61, classifying LL2 as eutrophic in 2019. Every summer since 2009, LL2 has been eutrophic based on chlorophyll-a (Figure 20). Also, LL2 has been eutrophic most summers since 2009 based on phosphorus enrichment and many summers due to reduced water clarity: • 82% of sample seasons eutrophic due to high TP concentrations • 45% of sample seasons eutrophic due to limited transparency

The trend over the last decade at LL2 was higher Secchi Disk TSI values, indicating a trend of reduced transparency. No significant trends were observed for chlorophyll-a and TP TSI values at LL2 (TCEH, 2018).

16 Lake Lawrence 2019

LL2 Trophic State Indices 70 65 60 55 Eutrophic 50 45 Mesotrophic TSI Score 40 35 Oligotrophic 30 25 20 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Chlorophyll-a TSI TP TSI Secchi TSI

Figure 20. LL2 Trophic State Index from 2009 to 2019.

SUMMARY

Thermal Stratification Mid-Summer Lake Lawrence was thermally stratified in mid-summer with a clinograde DO curve. Warmer, more oxygenated water existed on the surface in the epilimnion. Below this layer, the temperature and oxygen concentration declined with depth. The shallower site (LL2) showed signs of mixing in August. The process of turn-over was evident at both sites in September. By October, water quality was nearly homogenous throughout the water column indicating the process of turnover was complete. The trend from 2009 to 2018 was increased temperature in surface water at both locations from May to August (TCEH, 2018). Cyanobacteria have ecological and physiological adaptations that provide a competitive advantage over eukaryotic phytoplankton at greater water temperatures (Carey et al., 2012).

Reduced Transparency Transparency was greatest in early summer. Transparency declined each successive month from August to October. Transparency was negatively correlated to chlorophyll-a concentration at LL2. The relationship between transparency and chlorophyll-a was much weaker at LL2. The Seasonal Kendall test revealed a trend of reduced transparency for two-thirds of the sample season at both sites from 2009 to 2018 (TCEH, 2018). The downward trend in transparency continued in the 2019 sample season when transparency at both sites was less than the long-term average.

Chlorophyll-a The concentration of DO and chlorophyll-a was lower in June and July at both sites. Starting in August, chlorophyll-a levels increased each successive month. The concentration of DO and chlorophyll-a in the epilimnion peaked in October. At LL2, the concentration of chlorophyll-a was also high in May. The test for trends (TCEH, 2018) in chlorophyll-a concentration for 2009 to 2018 indicated a significant (p<0.05) increase in chlorophyll-a at both sites in August and at LL1 in May and October.

17 Lake Lawrence 2019 Nutrient Enrichment

Excess nutrients at Lake Lawrence contributes to eutrophication and algal blooms. For the entire 2019 sample season, the surface TP concentration was two to five times above the action level (0.020 mg/L) for lower mesotrophic lakes in the Puget Sound Lowlands ecoregion. The Seasonal Kendall test (2009 to 2018) revealed significant upward trends for TP in surface water (TCEH, 2018). At LL1, the mean annual TP has been above the state action level every year except 2013. The annual mean TP concentration at LL2 exceeded the state action level every sample season since 2009. The maximum surface TP concentration at LL2 occurred in 2019. Lake Lawrence has been phosphorus limited every year, except 2016 and 2017. LL1 was nitrogen limited in 2016 and 2017. At LL1, the TN concentration has increased each year since 2016, at both the surface and bottom. At LL2, the maximum concentration at the surface occurred in 2018 and at the bottom in 2019.

Classified as Eutrophic In 2019, both basins of Lake Lawrence were classified as eutrophic based on an average of the three TSI variables. Based on the concentration of chlorophyll-a, LL1 was classified as eutrophic every year that data was collected. For the period of record, TP enrichment classified LL1 as eutrophic three- quarters of sample seasons. Secchi depth was categorized as eutrophic one-quarter of sample seasons. The trend for TSI values at LL1 from 2009 to 2018 was toward eutrophication, with higher productivity, increased TP concentrations, and reduced water clarity (TCEH, 2018).

Every summer since 2009, LL2 has been eutrophic based on chlorophyll-a. Also, LL2 has been eutrophic nine out of eleven sample seasons since 2009 based on phosphorus enrichment and almost half of all sample seasons due to reduced water clarity: At LL2, trend analysis of TSI scores indicates a reduction in transparency. No significant trends were identified for chlorophyll-a and TP concentration at LL2.

Toxic Algae Human activity accelerates the rate of eutrophication through loading of nutrients from point and nonpoint sources. Cultural eutrophication is linked to algal blooms, degradation of water quality and biological integrity, and interference with recreational activities. Unfortunately, numerous harmful algal blooms have occurred at Lake Lawrence. Sixteen algae samples have been collected at Lake Lawrence that had microcystin toxin that exceeded the advisory level in 2009, 2010, 2013, 2015, 2017, 2018, and 2019. TCEH sampled algae nine times at Lake Lawrence from August to November 2019. Two samples tested positive for the biotoxin microcystin in mid-October

DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 https://www.co.thurston.wa.us/health/ehrp/annualreport.html For digital data contact the main telephone number or [email protected] For corrections, questions, and/or suggestions, contact the author of the 2019 report: [email protected]

18 Lake Lawrence 2019

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Carey, C.C., Ibelings, B.W, Hoffmann, E.P., Hamilton, D.P., Brookes, J.D. 2012. Eco-physiological adaptations that favour freshwater cyanobacteria in a changing climate. Water Resources (2012) 1394- 1407.

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

TCEH. 2009. Thurston County Environmental Health surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring.

TCEH. 2018. Lake Lawrence Annual Water Quality Report. Thurston County Environmental Health

TCPW. 2018. Aquatic nuisance weed control prescription: Lake Lawrence, Thurston County. Thurston County Public Works

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

19 Lake Lawrence 2019

Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control Appendix C. Toxic Algae

20 Lake Lawrence 2019

Appendix A. Raw data

Table A-1 Raw data collected at site LL1 located in the larger eastern basin of Lake Lawrence. Profile Samples Site INFO Temp ( C ) pH DO (m/l) Conductivity (Sp) Turb (FNU) TP TN Composite Sample Bottom Bottom Total Time Secchi Water Profile Sample Site Date Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a PDT (m) Color Depth Depth (m) (m) (m) LL1 5/22/2019 13:00 6.6 2.32 3 6.0 18.579 13.704 8.48 6.81 10.14 0.58 115.0 136.8 0.76 6.15 6 0.039 0.138 0.733 0.990 22.0 0.9 LL1 6/19/2019 13:20 6.33 1.24 3 6.0 20.864 14.733 8.75 6.74 9.54 0.57 117.9 194.7 1.19 12.35 6 0.052 0.927 0.881 1.850 19.0 1.1 LL1 7/24/2019 13:06 6.5 1.70 3 6.0 23.131 17.138 8.10 6.77 8.95 0.48 120.2 209.5 2.68 21.35 5.8 0.036 0.499 1.260 1.920 7.7 2.5 LL1 8/27/2019 13:02 6.1 1.30 3 6.0 22.442 19.404 8.48 6.66 9.78 0.46 125.3 207.9 6.09 38.94 5.4 0.048 0.213 0.959 2.040 28.0 2.3 LL1 9/24/2019 13:34 6.05 1.10 3 6.0 18.930 18.259 8.44 7.34 10.51 8.07 125.4 126.2 10.62 4.79 5.40 0.105 0.079 1.530 1.120 46.0 2.7 LL1 10/22/2019 14:18 6.04 0.76 3 5.5 12.958 12.578 8.70 8.48 11.27 10.52 122.6 123.0 22.85 16.03 5.50 0.070 0.070 1.660 1.800 60.0 5.8

Table A-2 Raw data collected at site LL2 located in the smaller western basin of Lake Lawrence. Profile Samples Site INFO Temp ( C ) pH DO (m/l) Conductivity (Sp) Turb (FNU) TP TN Composite Sample Bottom Bottom Total Time Secchi Water Profile Sample Site Date Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a PDT (m) Color Depth Depth (m) (m) (m) LL2 5/22/2019 13:33 5.94 1.73 6 5.75 18.311 11.638 8.85 6.79 10.90 0.57 115.4 190.2 1.06 18.66 5.5 0.034 0.188 0.744 1.620 34.0 1.1 LL2 6/19/2019 13:52 5.79 1.85 7 5.5 20.991 14.545 8.91 6.70 9.69 0.49 117.8 220.3 1.33 18.61 5.25 0.054 0.189 0.877 1.640 12.0 1.3 LL2 7/24/2019 13:36 5.7 1.10 3 5.0 23.338 18.832 8.67 6.70 9.77 0.54 119.8 181.3 4.66 21.68 5.1 0.051 0.180 1.260 1.880 17.0 2.0 LL2 8/27/2019 13:37 5.6 1.55 3 5.5 22.439 19.580 8.53 6.59 9.87 0.52 126.1 194.1 4.32 40.79 5 0.072 0.180 1.070 2.170 19.0 3.4 LL2 9/24/2019 14:07 5.5 1.20 3 5.0 18.934 18.111 8.07 7.15 9.80 7.76 125.6 125.8 5.97 6.04 5.00 0.061 0.071 1.100 1.300 30.0 4.3 LL2 10/22/2019 14:51 5.51 0.71 3 5.0 13.450 12.758 8.75 8.46 11.87 11.02 123.1 123.0 14.90 14.73 5.00 0.073 0.110 0.164 1.860 64.0 3.6

21 Lake Lawrence 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

St Clair, Summit, Hicks 5/21/2019 7:05 0.07 0.96 0.71 Ward, Pattison, Long, Black 5/22/2019 7:15 0.01 0.10 0.28 Deep, Offutt, Lawrence 5/23/2019 7:10 -0.03 -0.71 0.14 St Clair, Summit, Black 6/18/2019 7:15 0.14 -0.48 0.57 Ward, Hicks, Pattison, Long 6/19/2019 7:20 0.06 0.30 0.00 Deep, Offutt, Lawrence 6/20/2019 20:00 0.05 -7.18 0.57 St Clair, Summit, Black 7/24/2019 7:50 0.08 0.08 0.14 Deep, Offutt, Lawrence 7/25/2019 8:00 0.03 0.01 0.14 Ward, Hicks, Pattison, Long 7/26/2019 16:20 0.09 -6.62 0.43 St Clair, Summit, Black 8/27/2019 7:15 0.00 0.11 0.00 Deep, Offutt, Lawrence 8/28/2019 7:30 0.11 -0.36 0.14 Ward, Hicks, Pattison, Long 8/29/2019 7:30 0.26 -0.33 0.29 St Clair, Summit, Black 9/24/2019 7:30 0.21 -0.12 0.00 Deep, Offutt, Lawrence 9/25/2019 7:15 0.16 0.20 0.00 Ward, Hicks, Pattison, Long 9/26/2019 13:30 0.57 -0.12 0.14 St Clair, Summit, Black 10/22/2019 7:30 -0.16 -1.31 0.00 Ward, Hicks, Pattison, Long 10/23/2019 7:30 -0.03 0.76 0.14 Deep, Offutt, Lawrence 10/24/2019 13:15 -0.03 0.91 0.57 Median Percent Difference: 0.06 -0.06 0.14 Mean Percent Difference: 0.09 -0.77 0.24

22 Lake Lawrence 2019

23 Lake Lawrence 2019

Appendix C. Toxic Algae

Lake Lawrence Algal Toxins 1000

100

10 Microcystin Advisory Level 6.0 µg/L

µg/L 1 Anatoxin-a Advisory Level 1.0 µg/L

0.1

0.01 5/2/2010 6/6/2011 5/6/2013 4/1/2012 3/2/2014 4/6/2015 3/6/2017 2/4/2019 1/22/2010 8/10/2010 2/26/2011 9/14/2011 1/26/2013 8/14/2013 1/31/2016 5/10/2016 8/18/2016 4/10/2018 7/19/2018 7/10/2012 6/10/2014 9/18/2014 7/15/2015 6/14/2017 9/22/2017 5/15/2019 8/23/2019 12/1/2019 11/18/2010 12/23/2011 10/18/2012 11/22/2013 12/27/2014 10/23/2015 11/26/2016 12/31/2017 10/27/2018 Anatoxin-a Microcystin

Figure C-1. Algal toxin results for samples collected at Lake Lawrence from 2010 to 2019, showing 2019 Washington State Recreation Advisory Levels

2019 Long Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Long Lake map showing location of sample sites LO3 and LO4

HENDERSON INLET WATERSHED PUBLIC ACCESS: Washington Department of Fish and Wildlife • SHORELINE LENGTH: 7.1 miles public boat launch; City of Lacey, Long Lake • LAKE SIZE: 0.52 square miles Park; 10 small private community entries. • BASIN SIZE: 8.25 square miles • MEAN DEPTH: 3.7 meters (12 feet) GENERAL TOPOGRAPHY: • MAXIMUM DEPTH: 6.4 meters (21 feet) The watershed is relatively flat with extensive • VOLUME: 3,900 acre-feet wetlands between the lakes.

PRIMARY LAND USES: GENERAL WATER QUALITY: Primarily urban and suburban residential use, Fair – The north basin of Long Lake was with a small percentage in agriculture and classified as eutrophic from 2016 to 2019. The forest. Dense residential development exists trend from 2008 to 2018 was toward higher along the lake shore. productivity and reduced transparency. The south basin site LO4 was classified as eutrophic PRIMARY LAKE USES: two of the past four years. Trends from 2008 to Fishing, boating, swimming and other water 2018 were greater chlorophyll-a, surface TP, sports. and lower transparency. The 2019 surface TP concentration was above the action level (0.020 mg/L) for mesotrophic lakes in the Puget Lowlands. Since 2010, TCEH sampled Long Lake on 62 different dates for algal toxins. The algal toxin microcystin was detected above the Washington State advisory level ten times. Long Lake 2019

DESCRIPTION

Long Lake is the third lake in a series of four lakes connected by extensive wetlands. The first lake in the chain, Hicks Lake, flows south to Pattison Lake. A ditch constructed to float logs between Pattison and Long Lakes many years ago still connects the two lakes (Thurston Regional Planning Council, 2008). Water exits Long Lake through a surface outlet at the north end and flows to Lois Lake and Woodland Creek, which discharges into Henderson Inlet in north Thurston County.

Long Lake has two basins, north and south, which are connected by a narrow, shallow channel. The north basin is deeper (6 meters) than the south basin (4 meters). A small creek discharges into the south basin of Long Lake.

The Long Lake Management District supports activities, such as water quality monitoring, aquatic weed surveys and control, and alum (aluminum sulfate) treatments. In 2008, the south basin was treated with alum to reduce phosphorus and nuisance algae blooms.

METHODS

In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Long Lake from May to October. Figure 1 shows the sample sites, LO3 (north basin) and LO4 (south basin). Each site is in the deepest part of the basin. Table 1 lists the types of data collected and Appendix A provides the raw data. The Custer Color Strip (Figure 2) has been used as a reference for color of the lake’s water 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 of water on white portion of Secchi Disk at 1 Color #1 to #11 Custer Color Strip m • 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 Long Lake 2019

Figure 2. The Custer Color Strip is used to approximate the color of the lake’s water, viewed at 1-meter depth over the white section of the Secchi disk.

Quality Assurance and Quality Control (QA/QC)

TCEH collected 15% field replicates and field blanks for TP, TN, chlorophyll-a, and phaeophytin-a samples in 2019. Field blanks provide information about possible errors or contamination during collection and analysis. Field replicates (or duplicates) were collected to determine sampling and laboratory precision. The calibration of the Yellow Springs Instrument (YSI) EXO1 was verified before and after each sampling day. See Appendix B for all 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. Temperature (ᵒ C) Month Weather on Sample Day Monthly Average (Low/High) May Cloudy (16°C); 0-6 mph ENE wind 13 (2/30) June Cloudy (16°C); 0-5 mph W/Var wind 15 (4/33) July Fair, (21°C); 0-6 mph NNE wind 18 (8/32) August Fair, (25°C); 0-12 mph N wind 18 (7/33)

September Fair (18°C); 0-3 mph NE wind 14 (-1/26) October Partly cloudy (13°C); 0-9 mph NNE wind 8 (-6/18)

Vertical Water Quality Profiles

Long Lake is relatively shallow and polymictic. The vertical water quality profiles illustrate how the water column at Long Lake warmed to 3.5 meters depth from May to July. Below this depth, temperature and DO declined with depth, indicating stratification as surface temperatures warmed. Stratification was apparent at the deeper north basin site named LO3 until September. Stratification weakened at both sites, particularly LO4, in July. Warmer temperatures strengthened stratification briefly in August. By the September sample date, fall turn-over was evident at LO3 and almost complete at LO4. (Figures 3 to 8).

3 Long Lake 2019

LO3 - May 21, 2019 LO4 - May 21, 2019

Temperature (°C), pH (std), Temperature (°C), pH (std), 0 5 10 15 20 25 0 5 10 15 20 25 0 0

1 1 2

2 3 Depth (meters) Depth (meters) 4 3

5 4 0 40 80 120 160 0 40 80 120 160 SPC (µS/cm) SPC (µS/cm) TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 3. Vertical water quality profiles collected at for LO3 and LO4 in May 2019.

In May, surface of the lake was warming. The temperature difference between water in the photic zone (surface stratum penetrated by sunlight) and at the bottom was greater at the deeper site LO3 compared to the shallower site LO4: Transparency was greater than 3 meters at both sites in May, permitting sunlight to penetrate and photosynthesis to occur in deeper water. • LO3 Photic 18.1°C; DO 9.2 mg/L; pH 7.7 • LO4 Photic 18.1°C; DO 8.6 mg/L; pH 7.6 • LO3 Bottom 14.3°C; DO 2.2 mg/L; pH 6.9 • LO4 Bottom 17.8°C; DO 5.4 mg/L; pH 7.1

LO3 - June 18, 2019 LO4 - June 18, 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 Depth (meters) 4 Depth (meters) 3

5 4 0 40 80 120 160 0 40 80 120 160 SPC µS/cm SPC µS/cm

TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 4. Vertical water quality profiles collected at for LO3 and LO4 in June 2019.

In June, the warm surface layer remained 3.5 meters deep. At both sites, the temperature difference between the photic zone and bottom layer increased and the oxygen supply diminished at the bottom. Temperature differences in the water column created density heterogeneity, which reduced mixing, particularly at LO3. • LO3 Photic 21.8°C; DO 8.9 mg/L; pH 7.8 • LO4 Photic 21.6°C; DO 8.7 mg/L; pH 7.8 • LO3 Bottom 17.7 °C; DO 1.2 mg/L; pH 6.9 • LO4 Bottom 20.8°C; DO 4.7 mg/L; pH 7.2 4 Long Lake 2019

LO3 - July 25, 2019 LO4 - July 25, 2019 Temperature (°C), pH (std), DO Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 25 0 5 10(mg/L)15 20 25 0 0

1 1 2

3 2 Depth (meters) 4 Depth (meters) 3

5 4 0 40 80 120 160 200 0 40 80 120 160 200 SPC (µS/cm) SPC (µS/cm) TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 5. Vertical water quality profiles collected at for LO3 and LO4 in July 2019.

In July, the upper 3.5 meters continued to warm. Thermal stratification was weaker in July than it was in June. • LO3 Photic 22.7°C; DO 9.8 mg/L; pH 8.3 • LO4 Photic 22.6°C; DO 9.3 mg/L; pH 7.9 • LO3 Bottom 21.5°C; DO 2.3 mg/L; pH 6.9 • LO4 Bottom 22.3°C; DO 8.4 mg/L; pH 7.7

LO3 - August 28, 2019 LO4 - August 28, 2019 Temperature (°C), pH (std), DO Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 25 0 5 10(mg/L)15 20 25 0 0

1 1 2

3 2 Depth (meters) 4 Depth (meters) 3

5 4 0 40 80 120 160 200 0 40 80 120 160 200 SPC (µS/cm) SPC (µS/cm)

TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 6. Vertical water quality profiles collected at for LO3 and LO4 in August 2019.

In August, thermal stratification became stronger at both sites. • LO3 Epi 22.9°C; DO 10.4 mg/L; pH 8.9 • LO4 Epi 22.6°C; DO 10.0 mg/L; pH 8.6 • LO3 Hypo 21.5°C; DO 0.5 mg/L; pH 7.0 • LO4 Hypo 21.7°C; DO 3.8 mg/L; pH 7.3

5 Long Lake 2019

LO3 - September 25, 2019 LO4 - September 25, 2019 Temperature (°C), pH, DO (mg/L) Temperature (°C), pH, DO (mg/L) 0 5 10 15 20 25 0 5 10 15 20 0 0

1 1

2 3 Depth (meters) Depth (meters) 4 3

5 4 0 40 80 120 160 0 40 80 120 160

SPC (µS/cm) SPC (µS/cm)

TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 7. Vertical water quality profiles collected at for LO3 and LO4 in September 2019.

In September, air temperatures dropped, particularly after sunset. Surface waters cooled and sank, causing the water columns to mix. The differences in temperature, DO, and pH at the surface and the bottom were smaller than in August. • LO3 Photic 19.1°C; DO 10.2 mg/L; pH 8.6 • LO4 Photic 19.0°C; DO 11.1 mg/L; pH 8.7 • LO3 Bottom 18.6°C; DO 6.3 mg/L; pH 7.5 • LO4 Bottom Temp. 18.2°C; DO 9.6 mg/L; pH 8.3

LO3 - October 23, 2019 LO4 - October 23, 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 0 0

1 1 2

3 2

Depth (meters) 4

Depth (meters) 3

5 4 0 40 80 120 160 0 40 80 120 160 SPC (µS/cm) SPC (µS/cm)

TEMP pH TEMP pH D.O. SPC D.O. SPC

Figure 8. Vertical water quality profiles collected at for LO3 and LO4 in October 2019.

In October, the water quality at the surface and bottom of the lake were nearly homogeneous, indicating at both basins had turned over. • LO3 Photic 13.1°C; DO 9.1 mg/L; pH 7.6 • LO4 Photic 12.7°C; DO 10.4 mg/L; pH 7.9 • LO3 Bottom 12.9°C; DO 7.4 mg/L; pH 8.5 • LO4 Bottom 12.5°C; DO 9.9 mg/L; pH 7.7

6 Long Lake 2019

Color and Transparency

Color of the lake’s water can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. High concentrations of algae cause the color to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown.

Transparency of water to light has been used to approximate turbidity and phytoplankton populations. Secchi depth is closely correlated with the percentage of light transmission through water. The depth at which the Secchi disk is no longer visible approximates 10% of surface light, however suspended particles in the water affect accuracy. To protect public safety, the health department recommends visibility of at least 1.2 meters, or four feet, at public swimming beaches. Figure 9 shows the 2019 color, transparency, and chlorophyll-a concentration data for Long Lake sites LO3 and LO4.

Figure 9. Color, transparency, and chlorophyll-a concentration at LO3 and LO4 in 2019.

In 2019, the highest transparency occurred in early summer in May and June. The lowest transparency transpired in August and September. The Seasonal Kendall test revealed a trend of reduced transparency five out of six months at LO3 (transparency increased in October) and four months at LO4 from July to October (TCEH, 2018). In 2019, transparency was negatively correlated to chlorophyll-a concentration. Transparency was greater at LO3 compared to LO4: • LO3 mean 2.4; median 2.1 meters • LO4 mean 1.6; median 1.5 meters

7 Long Lake 2019

Figure 10 shows the annual average transparency (Secchi depth) compared to the long-term average (LTA). Negative values reflect transparency worse than the LTA. In 2019, transparency was slightly lower than the LTA: • LO3 was 0.1 meter lower • LO4 was 0.3 meters lower

Figure 10. Transparency at LO3 and LO4 compared to the long-term average (LTA).

Productivity

Pigments

Chlorophyll-a pigment is present in algae and cyanobacteria and is widely used to assess the abundance of phytoplankton in suspension. Phaeophytin is also a pigment, but it is not active in photosynthesis. It is a breakdown product of chlorophyll and is present in dead suspended material (Moss, 1967). Phaeophytin absorbs light in the same region of the spectrum as chlorophyll-a. If present, phaeophytin can interfere with acquiring an accurate chlorophyll-a value. The ratio of chlorophyll-a to phaeophytin-a has been used as an indicator of the physiological condition of phytoplankton in the sample.

2019 Productivity Data

Figure 11 shows that the highest concentration of chlorophyll-a occurred in August and September at both sites. The Seasonal Kendall test for trends from 2008 to 2018 for chlorophyll-a concentration indicates a significant (p<0.05) increase in chlorophyll-a concentration at both sites in August and September. A decreasing trend occurred at LO3 in October, which corresponds to the trend of increased transparency at this site in October (TCEH, 2018).

8 Long Lake 2019

Figure 4. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments, and the DO concentration in the photic zone or epilimnion at LO3 and LO4 in 2019.

The ratio of chlorophyll-a to phaeophytin-a peaked in early summer at LO3 and in May, June, and September at LO4. The ratio dropped dramatically in October at both sites. At LO3, DO in the upper strata peaked in July, remaining between 8.9 to 9.7 mg/L with a standard deviation of 0.3 mg/L. At LO4, the DO concentration was more variable (standard deviation 1.0 mg/L) and the upper water column gained oxygen from May to October.

In 2019, TCEH sampled Long Lake on seven different dates between June and October. Every sample was analyzed for microcystin. Some samples were also analyzed for anatoxin-a, cylindrospermopsin, and saxitoxin. None of these samples exceeded the Washington State advisory level for these four toxins. Microcystin algal blooms that exceeded the Washington State advisory level occurred at Long Lake in: August and September 2017 October and November 2015 September 2013 April 2016 October 2014 October 2011

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998). Figure 12 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at the two Long Lake sites.

9 Long Lake 2019

Figure 12. Surface concentration of TP and TN at LO3 and LO4 in 2019.

The concentration of TP at the surface increased each successive month until it peaked in September, when the process of turnover had begun after a period of weak stratification in August. The lowest surface TN occurred in May and June. At LO3, surface TN increased each successive month from July to September. At LO4, TN peaked in July, when mixing was evident, and again in September when cooler temperatures allowed the water column to mix more completely. TP and TN declined at both sites in October.

Total Phosphorus

10 Long Lake 2019

TP Action Level 0.020 mg/L

Figure 13. Concentration of TP at the surface and bottom of Long Lake at LO3 and LO4 in 2019.

At LO3, the greatest bottom TP concentration was collected in August, when thermal stratification was most stable in the north basin. At LO4, the water column was more mixed in July. At both sites, more thorough mixing of the water column was evident in September.

For samples collected during the 2019 sample season, the surface TP concentration (mg/L) was above the action level from July to October at LO3 and from June to October at LO4: • LO3 Surface Mean 0.032 • LO4 Surface Mean 0.035 • LO3 Surface Median 0.029 • LO4 Surface Median 0.035 • LO3 Surface Std Dev 0.019 • LO4 Surface Std Dev 0.015 • LO3 Surface Min. 0.013 in June and July • LO4 Surface Min. 0.015 in May • LO3 Surface Max. 0.063 in September • LO4 Surface Max. 0.056 in September

In 2019, the concentration of TP (mg/L) near the bottom was: • LO3 Bottom Mean 0.049 • LO4 Bottom Mean 0.043 • LO3 Bottom Median 0.049 • LO4 Bottom Median 0.045 • LO3 Bottom Std Dev 0.018 • LO4 Bottom Std Dev 0.016 • LO3 Bottom Min. 0.030 in May • LO4 Bottom Minimum 0.017 in May • LO3 Bottom Max. 0.078 in August • LO4 Bottom Maximum 0.065 in August

The concentration of TP near the bottom was lower at LO4 compared to LO3. This difference is likely due to the alum treatment in the south basin in 2008. The vertical profile graphs show that Long Lake exhibited a weak stratification with a clinograde oxygen curve at LO3 in July and August. The hypolimnion was not mixing with the oxygenated water above. At the same time, oxygen in the hypolimnion was consumed by redox processes like decomposition. Due to the lack of oxygen near the bottom, phosphorus stored in the sediments was released into the water column. This phosphorus

11 Long Lake 2019 accumulated in the hypolimnion until the deeper water mixed with the rest of the water column starting in September.

The Seasonal Kendall test (2008 to 2018) revealed significant trends for TP in surface water at LO4: • Reduced TP concentration in June (-0.003 mg/L) • Increased TP concentration from July to October (+0.002 to 0.008 mg/L)

At LO3, no significant trends were detected, except for a reduction (-0.002 mg/L) in July (TCEH, 2018).

Nitrogen

Nitrogen is also limiting to lake productivity, but supplies are more readily augmented by inputs from external sources. The State of Washington does not have established action or cleanup levels for surface total nitrogen. The average total surface nitrogen concentration was 0.596 mg/L at LO3 and 0.526 mg/L at LO4. Figure 14 shows the 2019 TN concentrations for the two sites at Long Lake.

Figure 14. Concentration of TN at the surface and bottom of Long Lake at LO3 and LO4 in 2019.

At LO3, surface TN increased each month from June until September, with the largest gain in July. Likewise, a dramatic rise of TN at the surface in July occurred at LO4. Mixing of the water column was evident from August to October at the shallower site LO4.

The Seasonal Kendall test (2008 to 2018) showed a significant (p<0.05) upward trend of surface TN from July to October at both sites (TCEH, 2018). TN also increased in May at LO4. No trends were detected in May for LO3 and in June for both sites.

Weak thermal stratification created low DO conditions, which resulted in increased bottom TN. Ammonia-nitrogen released from the bottom sediments accumulated in the hypolimnion. When mixing began, these nitrogen compounds from the sediments contributed to TN at the surface. LO4 mixed earlier in the summer, likely due to the shallower depth in the south basin.

12 Long Lake 2019

Historic Nutrient Data: TP

Figure 15 displays the average annual concentration of total phosphorus at LO3 from 1981 to 2019, except for 2017 when TP was not collected. For these 37 sample seasons at LO3, the surface TP mean/median was 0.028/0.023 mg/L. The surface samples for total phosphorus have been above the state action level (purple line at 0.020 mg/L) for 65% of the period of record.

Figure 15. Mean Total Phosphorus concentration from samples collected at LO3 from 1981 to 2019 and at LO4 from 1983 to 2019 (TP samples were not collected in 2017).

At the south basin site (LO4), surface TP was collected from 1983 to 2019, except for in 2017. At LO4, the mean/median for these 36 sample seasons is 0.032 mg/L. The surface TP concentration at LO4 exceeded the state action level 69% of sample seasons since 1983. The concentration of TP at both the surface and bottom declined in 2008 after the alum application. From 2007 to 2008, the surface TP concentration dropped 0.03 mg/L; the bottom concentration fell 0.07 mg/L.

Historic Nutrient Data: TN

Figure 16 displays the mean annual TN concentrations from 1995 to 2019. For the entire period of record (25 sample seasons), the surface/bottom concentration (mg/L) for the two Long Lake sites are: LO3 LO4 • Mean 0.472/0.608 • Mean 0.546/0.592 • Median 0.457/0.506 • Median 0.563/0.608 • Standard deviation 0.091/0.291 • Standard deviation 0.143/0.145 • Minimum 0.300/0.350 in 2011 • Minimum 0.272/0.282 in 2008 (alum) • Maximum 0.709 in 2001/1.690 in 2017 • Maximum 0.805 in 1999/0.841 in 2004

13 Long Lake 2019

Figure 16. Mean Total Nitrogen concentration from samples collected at LO3 and LO4 from 1995 to 2019. Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 17 shows the TN to TP ratio at the two Long Lake sites. The ratio has been above 10 every year except 2016.

Figure 17. TN:TP at LO3 and LO4 from 1995 to 2018. No TP samples collected in 2017.

14 Long Lake 2019

Trophic State Indices (TSI)

Table 3. Trophic State Index variables. TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

The 2019 TSI results (Figure 18) for the Long Lake sites are LO3 mean TSI score: 53 eutrophic LO4 mean TSI score: 55 eutrophic • Chlorophyll-a: 58 eutrophic • Chlorophyll-a: 57 eutrophic • Total Phosphorus: 54 eutrophic • Total Phosphorus: 55 eutrophic • Secchi Disk: 47 eutrophic • Secchi Disk: 52 eutrophic

Figure 18. LO3 and LO4 Trophic State Index scores from 1983 to 2019. For the entire period of record, the Long Lake sites have been classified as eutrophic (% of sample seasons): LO3 Chlorophyll-a: 97% LO3 Total Phosphorus: 38% LO3 Secchi Disk: 12% LO4 Chlorophyll-a: 87% LO4 Total Phosphorus: 55% LO4 Secchi Disk: 47%

15 Long Lake 2019

The Mann Kendall test (2008 to 2018) revealed a significant trend (p˂0.05) of increasing TSI values for chlorophyll-a concentration and transparency at LO3 (TCEH, 2018). No trend was detected for TP concentration at LO3. The south basin (LO4) has become more eutrophic. All three TSI indicators had significant upward trends (p˂0.05).

SUMMARY

Thermal Stratification In 2019, the water column at Long Lake began to stratify in May. Stratification was apparent at the deeper north basin site named LO3 until September. Stratification weakened at both sites, particularly LO4, in July. Warmer temperatures strengthened stratification briefly in August. By the September sample date, fall turn-over was evident at LO3 and almost complete at LO4. The trend from 2008 to 2018 was increased temperature in surface water at both locations from May to August (TCEH, 2018).

Water Transparency In 2019, transparency was lower than the long-term average at both sites. Transparency was greater at the north basin site and was negatively correlated to productivity. The general trend from 2008 to 2018 was a decrease in transparency for both basins, except for the north basin in October, where the trend was increased transparency (TCEH, 2018).

High Productivity in August and September Like in 2018, the highest concentration of chlorophyll-a of the 2019 sample season in both basins occurred in August and September. The Seasonal Kendall test for chlorophyll-a concentration indicated a significant (p<0.05) increasing trend at both sites in August and September from 2008 to 2018 (TCEH, 2018). A decreasing trend of chlorophyll-a occurred at the north basin LO3 site in October, which correlates to the trend of greater transparency at LO3 in October.

High Concentrations of Nutrients and Trends Cultural eutrophication is linked to algal blooms, degradation of water quality and biological integrity, and interference with recreational activities. Human activity accelerates the rate of eutrophication through loading of nutrients from point and non-point sources. Excess nutrients at Long Lake contribute to eutrophication and algal blooms. Since 2010, TCEH sampled Long Lake on 62 different dates for algal toxins. The algal toxin microcystin was detected above the Washington State advisory level ten times.

The average surface TP concentration was 0.032 mg/L at LO3 and 0.035 mg/L at LO4 in 2019, up from the 2018 average of 0.030 mg/L at both sites. This concentration is above the action level (0.020 mg/L) for mesotrophic lakes in the Puget Lowlands. The Seasonal Kendall test (2008 to 2018) revealed the following significant trends for TP in surface water at the south basin site LO4, where alum was applied in 2008: less surface TP in June and greater surface TP from July to October. At the north basin site, the only significant trend detected was a decline in surface TP in July (TCEH, 2018).

The average total surface TN concentration was 0.5 to 0.6 mg/L at both sites. The Seasonal Kendall test shows a significant (p<0.05) upward trend of surface TN concentrations from July to October at both sites. No trends were detected in May and June (TCEH, 2018).

16 Long Lake 2019

Classified as Eutrophic For the 32 sample seasons with adequate chlorophyll-a, surface TP, and Secchi depth data, the north basin site LO3 was classified as eutrophic 56% of the time. For the six samples from 1984 to 1990, LO3 was classified as mesotrophic. From 1991 to 2000, LO3 was eutrophic half the sample seasons. After 2000, LO3 was classified eutrophic over three-quarters of the sample seasons. From 2016 to 2019, LO3 was classified as eutrophic every year based on the average TSI Score. The trend from 2008 to 2018 in the north basin was toward eutrophication, with higher productivity and reduced transparency No trend was detected for TP concentration at LO3 (TCEH, 2018).

For the period of record, the south basin site LO4 was eutrophic 65% of sample seasons, a higher percentage due to persistent eutrophic conditions from 1989 to 2007, before the alum application. LO4 was classified as eutrophic two of the past four years. Trend analysis showed that the south basin grew more eutrophic from 2008 to 2018. All three TSI indicators had significant upward trends (TCEH, 2018).

DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 or https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59. 17 Long Lake 2019

Thurston Regional Planning Council. 2008. Shoreline inventory for the cities of Lacey, Olympia, and Tumwater and their urban growth areas. Olympia, Washington.

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

18 Long Lake 2019

Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control

19 Long Lake 2019

Appendix A. Raw data

Table A-1 Raw data collected at site LO3 located in the north basin of Long Lake. Profile Samples Site INFO Temp ( C ) pH DO (m/L) Spec Cond (µS/cm) Turb (FNU) TP (mg/L) TN (mg/L) Composite Sample (µg/L) Bottom Bottom Total Secchi Water Profile Sample Site Date Time Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a (m) Color Depth Depth (m) (m) (m) LO3 5/21/2019 10:37 5.8 3.80 6 5.0 18.149 14.280 7.75 6.90 9.23 2.20 140.2 154.0 0.21 1.24 5.3 0.013 0.030 0.133 0.170 4.8 0.4 LO3 6/18/2019 12:01 5.75 4.10 6 5.5 21.775 17.653 7.78 6.90 8.94 1.21 145.2 166.0 -0.78 2.83 5.3 0.013 0.057 0.305 0.449 2.7 0.2 LO3 7/25/2019 10:03 5.47 2.32 3 5.0 22.789 21.467 8.33 6.91 9.81 2.27 151.5 157.2 2.37 2.20 5 0.026 0.053 0.632 0.549 10.0 0.8 LO3 8/28/2019 11:41 5.33 1.05 3 5.0 22.955 21.511 8.89 6.99 10.43 0.52 154.7 169.0 5.78 6.57 5 0.045 0.078 0.699 0.631 28.0 2.6 LO3 9/25/2019 12:48 5.49 1.12 3 5.0 19.361 18.622 8.66 7.45 10.64 6.25 154.5 156.4 7.70 2.35 5.00 0.063 0.045 0.849 0.502 42.0 4.2 LO3 10/23/2019 13:16 5.5 1.90 6 5.0 13.114 12.879 7.60 7.44 9.15 8.48 152.7 152.5 2.70 2.27 5.00 0.031 0.031 0.558 0.593 15.0 2.8

Table A-2 Raw data collected at site LO4 located in the south basin of Long Lake. Profile Samples Site INFO Temp ( C ) pH DO (m/L) Spec Cond (µS/cm) Turb (FNU) TP (mg/L) TN (mg/L) Composite Sample (µg/L) Bottom Bottom Total Secchi Water Profile Sample Site Date Time Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a (m) Color Depth Depth (m) (m) (m) LO4 - S Basin 5/21/2019 10:07 4.44 3.25 3 4.0 18.048 17.754 7.67 7.13 8.64 5.42 149.5 155.2 0.21 1.58 3.9 0.015 0.017 0.161 0.171 6.1 0.4 LO4 - S Basin 6/18/2019 11:35 4.4 2.20 3 4.0 21.578 20.809 7.82 7.18 8.68 4.65 153.6 156.4 -0.08 1.24 3.9 0.023 0.047 0.298 0.417 6.4 0.8 LO4 - S Basin 7/25/2019 9:37 4.19 1.46 8 4.0 22.619 22.315 7.91 7.70 9.34 8.41 160.2 160.7 3.09 6.34 3.5 0.033 0.036 0.836 0.609 11.0 3.4 LO4 - S Basin 8/28/2019 11:08 4 0.80 3 3.9 22.830 21.738 8.62 7.31 10.21 3.84 165.2 169.1 4.92 194.31 3.75 0.046 0.065 0.629 0.708 25.0 3.6 LO4 - S Basin 9/25/2019 12:21 4.17 0.93 7 4.0 19.042 18.182 8.68 8.26 11.10 9.59 163.5 163.6 10.06 7.67 3.75 0.056 0.052 0.862 0.942 32.0 3.1 LO4 - S Basin 10/23/2019 12:41 4.33 1.50 8 4.0 12.848 12.462 7.91 7.65 10.38 9.82 162.0 162.1 2.62 8.42 4.00 0.037 0.042 0.632 0.667 12.0 5.5

20 Long Lake 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

21 Long Lake 2019

2018 and 2019 Offutt Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Offutt Lake map showing location of sample site OF1.

PART OF DESCHUTES RIVER WATERSHED PUBLIC ACCESS: The Washington Department of Fish and Wildlife • SHORELINE LENGTH: 2.9 miles operates one public boat launch on the north side of • LAKE SIZE: 0.30 square miles (195 acres) the lake off 116th Ave SE. • BASIN SIZE: 2.7 square miles • MEAN DEPTH: 4.6 meters (15 feet) GENERAL TOPOGRAPHY: • MAXIMUM DEPTH: 7.6 meters (25 feet) Offutt Lake is a Puget Sound lowland lake at an • VOLUME: 2,900 acre-feet elevation of 234 feet above mean sea level.

PRIMARY LAND USES: GENERAL WATER QUALITY: The Offutt (also spelled Offut) Lake watershed is Fair – The average of three TSI values categorized primarily suburban residential with some Offutt Lake is eutrophic in 2018 and mesotrophic undeveloped forest cover primarily in wetland areas. 2019. The surface TP concentration exceeded the The sample site OF1 is near a private swim area on action level for mesotrophic lakes both years. Based the northern side of the lake (Figure 1). on the surface TP concentration alone, Offutt lake would be classified as eutrophic in both 2018 and PRIMARY LAKE USE: 2019. There were multiple reports of algal blooms Offutt Lake is used for fishing, swimming, and with surface scum in 2018, but none of the samples boating (5 mph). exceeded the Washington Advisory level for algal toxins. Offutt Lake 2018 and 2019 DESCRIPTION

Offutt Lake is located eleven miles south of Olympia in Thurston County, Washington. This relatively shallow lake (maximum depth 7.6 meters) has one small perennial inlet stream and one outlet stream that flows to the Deschutes River. The lake is also fed by several springs (Bortleson et al., 1976).

Approximately 60% of the shoreline has been developed, primarily for single-family residences. Most of the development is on the north and south shorelines, with 45 to 50 developed parcels on each side. The Offutt Lake Resort, along with other community and commercial properties are on the south shore. The undeveloped eastern shore (20% of the total shoreline) has wetlands and both submerged and emergent aquatic macrophytes. The remaining 20% of shoreline on the western side of the lake is bordered by larger parcels of undeveloped land that supports forest and grasslands.

Soils in the watershed include: • Everette very gravelly sandy loam (3 to 30%): deep excessively drained soil on terraces and outwash plains • Spanaway gravelly sandy loam (3 to 15% slopes): very deep, somewhat excessively drained soil on terraces • Godfrey silty clay loam (0 to 3 % slope): deep, poorly drained soil in depressions on flood plains • Mukilteo muck (0 to 2% slope): very deep, very poorly drained soils in upland depressions

The Washington Department of Fish and Wildlife (WDFW) maintains a public boat ramp on the north side of the lake which is open year-round. WDFW stocks with rainbow trout, cutthroat trout, and occasionally brown trout. The most abundant fish is largemouth bass, followed by rainbow trout. The lake also supports populations of yellow perch, brown bullhead catfish, pumpkinseed sunfish, largescale suckers, redside shiner, and sculpin. Coho salmon have been collected in Offutt lake and may have entered the lake as smolts when the Deschutes River flooded (Couto and Caromile, 2007). In 2006, Offutt Lake was listed as Category 5 (polluted waters requiring clean-up) for polychlorinated biphenyls (PCBs) and Category 2 (waters of concern) for 2,3,7,8- tetrachlorodibenzo-P-dioxin (2,3,7,8-TCDD, also referred to simply as dioxin) in fish tissue. These listings are a result of a 2006 toxicology study of largemouth bass, rainbow trout, and yellow perch.

METHODS

In 2018 and 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Offutt Lake from May to October. Figure 1 shows the sample site OF1, 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.

2 Offutt Lake 2018 and 2019

Figure 2. TCEH compared water color to the Custer Color Strip.

Quality Assurance and Quality Control (QA/QC)

RESULTS

Weather Conditions

Weather conditions during the 2018 and 2019 sample season are provided in Table 2.

Table 2. Weather on 2018 and 2019 sample days and the average, minimum, and maximum air temperatures for each month from Camelot-KWAOLYMP150 weather station.

2018 Temperature 2019 Temperature (ᵒ C) Monthly (ᵒ C) Monthly Month 2018 Weather on Sample Day 2019 Weather on Sample Day Average Average (Low/High) (Low/High)

Fair (21°C); 0-3 mph Variable Partly cloudy, (13°C); 0-5 mph S May 13 (2/31) 13 (2/30) wind wind Mostly cloudy (19°C); 0-6 mph Partly cloudy, (18°C); 0-13 mph W June 14 (4/32) 15 (4/33) SSW wind wind Partly cloudy, (23°C); 0-7 mph Partly cloudy, (13°C); 0-5 mph S July 19 (6/34) 19 (8/32) W wind wind

Hazy from wildfire smoke, August 18 (7/35) Fair (22°C); 0-6 mph ENE wind 18 (7/33) (27°C); 0-5 mph NNE wind

Fair (18°C); 0-6 mph Variable Cloudy (18°C); 0-8 mph WSW September 13 (2/29) 14 (-1/26) wind wind Fair to partly cloudy (14°C); 0-8 October Cloudy (11°C); 0 mph Calm 9 (0/22) 8 (-6/18) mph WSW wind

3 Offutt Lake 2018 and 2019 Vertical Water Quality Profiles

The vertical water quality profiles illustrate how the water column at Offutt Lake changed over the sample seasons in 2018 and 2019 (Figures 3 to 7).

Offutt Lake - May 23, 2018 Offutt Lake - May 22, 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

Depth (meters) 5 Depth (meters) 5

6 6

7 7 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 3. Vertical water quality profiles for OF1 collected in May 2018 and 2019.

In May, a layer of warm water floated on a layer of cooler, denser water below. Stratification was starting, but the layers were not yet well defined. In 2018, the sample day was 8°C warmer and the upper water column was 3°C warmer compared to 2019. • May 2018 Epilimnion – Temp 20.3°C; DO 9.4 mg/L • May 2018 Hypolimnion – Temp 11.2°C; DO 1.3 mg/L

In 2019, upper layer was cooler and extended two meters deeper than in May 2018. Uniform temperature in this upper layer indicates mixing. Below 3 meters depth, the profile shows sharp density difference in deeper water. • May 2019 Epilimnion – Temp 17.3°C; DO 9.2 mg/L • May 2019 Hypolimnion – Temp 9.9°C; DO 0.7 mg/L

In both 2018 and 2019, a clinograde DO curve was forming. 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.

4 Offutt Lake 2018 and 2019

Offutt Lake - June 27, 2018 Offutt Lake - June 19, 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 Depth (meters) 5 Depth (meters) 5

6 6

7 7 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC µS/cm SPC µS/cm

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 4. Vertical water quality profiles for OF1 collected in June 2018 and 2019.

In June, the average daily air temperature increased, heating the epilimnion. This heat was retained because the overnight air temperature remained warmer, as well (Table 2). In June 2018, the epilimnion grew over two meters deeper than it was in May. • June 2018 Epilimnion – Temp 21.0°C; DO 8.8 mg/L • June 2018 Hypolimnion – Temp 11.8°C; DO 0.5 mg/L

The dissolved oxygen (DO) profile was a weak positive heterograde curve. The water column was sufficiently transparent (3.4 meters Secchi depth) to permit photosynthesis in deeper water, where excess oxygen accumulated due to the reduced mixing of the water column (Wetzel, 1983).

In 2019, the epilimnion depth remained about the same depth (3.5 meters) throughout stratification. • June 2019 Epilimnion – Temp 20.2°C; DO 9.1 mg/L • June 2019 Hypolimnion – Temp 12.5°C; DO 0.6 mg/L

The DO curve was clinograde in June 2019. The concentration of DO in the hypolimnion was low due to redox processes in the hypolimnion, which was isolated from more oxygenated water above by density differences during thermal stratification.

5 Offutt Lake 2018 and 2019

Offutt Lake - July 18, 2018 Offutt Lake - July 19, 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 Depth (meters) Depth (meters) 5 5

6 6

7 7 0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 5. Vertical water quality profiles for OF1 collected in July 2018 and 2019.

Average air temperatures reached the summer maximum in July (Table 2), likewise epilimnion water temperatures peaked. Three distinct layers were readily discernable, indicating that density differences hindered mixing of the water column. The temperature difference between the epilimnion and hypolimnion was greatest in July in both 2018 and 2019 (Figure 5). • 2018 July Epilimnion – Temp 24.5°C; DO 8.6 mg/L • 2018 July Hypolimnion – Temp 13.3°C; DO 0.7 mg/L

In 2018, the dissolved oxygen (DO) profile was a very weak positive heterograde curve. Transparency remained relatively high (3.4 meters Secchi depth) in July, which permitted photosynthesis in deeper water. The oxygen supply was marginally higher in the cooler water in the metalimnion.

The DO curve was clinograde in June 2019. The concentration of DO in the hypolimnion was low, which was isolated from more oxygenated water above by density differences during thermal stratification. • 2019 July Epilimnion – Temp 21.7°C; DO 8.7 mg/L • 2019 July Hypolimnion – Temp 13.7°C; DO 0.6 mg/L

6 Offutt Lake 2018 and 2019

Offutt Lake - August 15, 2018 Offutt Lake - August 27, 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 Depth (meters) Depth (meters) 5 5

6 6

7 7 0 40 80 120 160 200 240 0 40 80 120 160 200 240 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 6. Vertical water quality profiles for OF1 collected in August 2018 and 2019.

The average air temperature cooled slightly in August, as did the temperature in the epilimnion. In 2018, the epilimnion reached a depth of 3.6 meters. • 2018 August Epilimnion – Temp 23.2°C; DO 8.9 mg/L • 2018 August Hypolimnion – Temp 16.3°C; DO 0.9 mg/L

In 2019, the epilimnion remained approximately the same depth (3.5 meters) from May until August. • 2019 August Epilimnion – Temp 21.2°C; DO 8.3 mg/L • 2019 August Hypolimnion – Temp 15.4°C; DO 0.5 mg/L

A clinograde curve was evident in August 2018 and 2019. Contact with the atmosphere and photosynthesis contributed to oxygen in the epilimnion. The hypolimnion was cut-off from the surface oxygen supply. Anoxic conditions were likely due to redox processes, like decomposition and advection of low oxygen groundwater.

7 Offutt Lake 2018 and 2019

Offutt Lake - September 19, 2018 Offutt Lake - September 24, 2019

Temperature (°C), pH, DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0

1 1

2 2

3 3 Depth (meters) Depth (meters) 4 4

5 5

6 6

7 7 0 40 80 120 160 200 240 0 40 80 120 160 200 240 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 7. Vertical water quality profiles from OF1 collected in September 2018 and 2019.

In September, average air temperatures declined, especially overnight. The water columns began to mix. In 2018, the lake turned over and only the upper meter of surface water remained warmer and more oxygenated. Internal loading provided a phosphorus boost in in this phosphorus-limited lake. As a result, productivity boomed, and photosynthesis combined with cooler temperatures produced the maximum DO concentration for the season. • September Photic Zone (Secchi Depth 0.8 meters) – Temp 18.2°C; DO 10.6 mg/L • September Bottom Measurement (5 meters) – Temp 17.7°C; DO 9.6 mg/L

In 2019, the bottom of Offutt Lake was cold and anoxic. The lake had mixed to 5.5 meters depth. In contrast the 2018 sample season, the minimum DO concentration for the sample season occurred September. The surface oxygen supply declined each successive month from May until September. • September Photic Zone (Secchi Depth 1.8 meters) – Temp 18.0°C; DO 7.4 mg/L • September Bottom Measurement (5 meters) – Temp 15.3°C; DO 0.6 mg/L

8 Offutt Lake 2018 and 2019 Offutt Lake - October 24, 2018 Offutt Lake - October 22, 2019

Temperature (°C), pH (std), DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0

1 1

2 2 3 3 4 Depth (meters) Depth (meters) 4 5

5 6

6 7 0 20 40 60 80 0 20 40 60 80 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 8. Vertical water quality profiles from OF1 collected in October 2018 and 2019.

In October, the weather turned colder. The surface water continued to cool and sink, diminishing vertical differences of water quality parameters. Offutt Lake was isothermal. The minimum surface temperature for the season occurred in October. • October Photic Zone (Secchi Depth 2.1 meters) – Temp 12.9°C; DO 6.4 mg/L • October Bottom Measurement (4.5 meters) – Temp 12.9°C; DO 5.6 mg/L

In October 2019, Offutt Lake completely turned over. The surface DO reached the maximum for the season, likely a result of cooler temperatures as productivity was below average. • October Photic Zone (Secchi Depth 3.4 meters) – Temp 12.4°C; DO 9.2 mg/L • October Bottom Measurement (4.5 meters) – Temp 12.4°C; DO 9.1 mg/L

Water Transparency and Color

Figures 9 and 10 show the Secchi depth (bar length), color (color of the bar), and chlorophyll-a concentration (purple line) at OF1 for 2018 and 2019.

9 Offutt Lake 2018 and 2019 2018 offutt Lake Water Transparency and Color May June July August September October 0.00 90 0.50 80 1.00 70 1.50 60 a (µg/L) 2.00 50 - 2.50 40 3.00 30 chlorophyll Secchi depth (meters) 3.50 20 4.00 10 4.50 0 Secchi (meters) Chl a (µg/L)

Figure 9. Water color, Secchi depths, and chlorophyll-a concentrations at OF1 in 2018.

In 2018, the mean transparency for the sample season was 2.9 meters (median 3.4 meters). Secchi depth was negatively correlated with the chlorophyll-a concentration. Productivity, as measured by the chlorophyll-a concentration, was lowest (mean 4.1 µg/L) in the early summer (May to August), when the mean Secchi depth was 3.6 meters. In September, when Offutt Lake turned over, internal loading increased the surface phosphorus by five times above the early summer mean, causing productivity to spike almost twenty times greater. Transparency plummeted from 3.6 meters (mean for May to August) to 0.8 meters in September during an algal bloom.

2019 Offutt Lake Water Transparency and Color May June July August September October 0.00 90 0.50 80 1.00 70 1.50 60 a (µg/L) 2.00 50 - 2.50 40 3.00 30 chlorophyll

Secchi depth (meters) 3.50 20 4.00 10 4.50 0 Secchi (meters) Chl a (µg/L)

Figure 10. Water color, Secchi depths, and chlorophyll-a concentrations at OF1 in 2019.

For the 2019 season, the greatest Secchi depth (3.4 meters) occurred in May and October. The mean transparency was 2.7 meters (median 2.9 meters). Like 2018, the lowest transparency of the sample season occurred in September 2019, but the lake had not yet completely turned over. The surface TP in September 2019 was lower, less than three times higher than the early summer average.

The color of the water (shown as the bar color in Figures 10 and 11), based on the reference Custer Color Strip, varied more in 2018 compared to 2019. Lake color was likely affected by changes in the algae and cyanobacteria communities; phytoplankton identification would provide more information about productivity and phytoplankton assemblages.

10 Offutt Lake 2018 and 2019 Productivity

Pigments

2018 and 2019 Productivity Data

In 2018, the concentration of chlorophyll-a crested after turnover in September (Figure 11) and remained higher than average in October. Transparency was lowest these two months; transparency was negatively correlated (R²=0.86) to productivity (Appendix C). The surface supply of oxygen (10.6 mg/L) was highest in September, when productivity peaked. Phaeophytin-a spiked twice, once in June and again in September.

2018 Offutt - Chlorophyll-a and Ratio Chlorophyll-a to Phaeophytin-a 100 40

80 30 60 20 40 10 -a a:Phaeo

20 - DO (mg/L) µg/L) and Epilimnion 0 0 a ( - May June July August September October Chlor

Chlor Chlorophyll-a Epilimnion DO (mg/L) Ratio Chlor-a : Phaeo-a

Figure 11. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments, and DO concentration in the photic zone or epilimnion collected at OF1 in 2018.

Much like the 2018 sample season, productivity increased in September 2019 (Figure 12). The concentration of phaeophytin-a was highest in September, as well. Unlike 2018, the surface oxygen supply in September 2019 was at the minimal concentration (7.4 mg/L) for the sample season. Surface DO in May was 9.2 mg/L. It declined each successive month until the increase in October back to 9.2 mg/L. Transparency was not correlated to productivity (Appendix C).

2019 Offutt - Chlorophyll-a and Ratio Chlorophyll-a to Phaeophytin-a

10 40

8 30 6 20 a (µg/L) and - 4

10 -a a:Phaeo

2 - Chlor Epilimnion DO (mg/L) 0 0 May June July August September October Chlor

Chlorophyll-a Epilimnion DO (mg/L) Ratio Chlor-a : Phaeo-a

Figure 12. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments, and DO concentration in the photic zone or epilimnion collected at OF1 in 2019. 11 Offutt Lake 2018 and 2019 In 2018, citizens reported algal blooms with surface scum in May, July, September, and October. During these blooms, TCEH collected five samples, which were tested algal toxins. None of the samples exceeded the Washington State Toxic Algae Advisory Level for microcystin, anatoxin-a, cylindrospermopsin, or saxitoxin. Offutt Lake was not sampled for toxic algae in 2019.

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998). Figures 13 and 14 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at OF1 in 2018 and 2019.

2018 Offutt Lake - Surface Total Phosphorus & Total Nitrogen 1.60 0.07 1.40 0.06 1.20 0.05 1.00 0.04 0.80 0.03 0.60 0.02 TP (mg/L) TP

TN (mg/L) 0.40 0.20 0.01 0.00 0.00 May June July August September October Surface TN Surface TP

Figure 13. 2018 surface concentration of TP and TN at OF1.

2019 Offutt Lake - Surface Total Phosphorus & Total Nitrogen 1.60 0.07 1.40 0.06 1.20 0.05 1.00 0.04 0.80 0.03 0.60 0.02 TP (mg/L) TP TN (mg/L) 0.40 0.20 0.01 0.00 0.00 May June July August September October Surface TN Surface TP

Figure 14. 2019 surface concentration of TP and TN at OF1.

In both 2018 and 2019, concentration of TP at the surface peaked when the water column began to mix in September. Thermal stratification reduced internal loading to surface waters from June to August; changes in the phytoplankton community and external sources likely affect nutrient levels during stratification.

12 Offutt Lake 2018 and 2019 Total Phosphorus

In 2018, the concentration was higher at the bottom from June to August. Three defined layers were recognizable in the vertical profiles during those three months indicating thermal stratification. During stratification, the hypolimnion was mostly stagnant, not mixing with the oxygenated water above. At the same time, oxygen in the hypolimnion was consumed by redox processes like decomposition. Due to the lack of oxygen near the bottom, phosphorus stored in the sediments was released into the water column. This phosphorus accumulated in the hypolimnion, until turn-over in September, when the water column mixed and productivity boomed.

In 2018, the TP concentrations were: • 2018 TP Surface Mean 0.028 mg/L • 2018 TP Bottom Mean 0.195 mg/L • 2018 TP Surface Median 0.014 mg/L • 2018 TP Bottom Median 0.123 mg/L • 2018 TP Surface Std Dev 0.022 mg/L • 2018 TP Bottom Std Dev 0.181 mg/L

2018 Offutt Lake - Total Phosphorus 1.00

0.80

0.60 TP Action Level 0.40 0.020

mg/L 0.20

0.00 May June July August September October Surface TP Bottom TP

Figure 15. Concentration of Total Phosphorus at the surface and bottom at OF1 in 2018.

In 2019, the TP concentration at the bottom steadily increased from May to September. The bottom strata fully mixed with the rest of the water column in October. In 2019, the TP concentrations were: • 2019 TP Surface Mean 0.030 mg/L • 2019 TP Bottom Mean 0.308 mg/L • 2019 TP Surface Median 0.028 mg/L • 2019 TP Bottom Median 0.251 mg/L • 2019 TP Surface Std Dev 0.014 mg/L • 2019 TP Bottom Std Dev 0.276 mg/L

2019 Offutt Lake - Total Phosphorus 1.00

0.80 TP 0.60 Action Level 0.40 0.020

mg/L 0.20

0.00 May June July August September October Surface TP Bottom TP

Figure 16. Concentration of Total Phosphorus at the surface and bottom at OF1 in 2019.

13 Offutt Lake 2018 and 2019 Nitrogen

Nitrogen is also limiting to lake productivity, but supplies are more readily augmented by inputs from external sources. The State of Washington does not have established action or cleanup levels for surface total nitrogen. In 2018, the surface TN was more variable, and the surface maximum, which occurred after turn-over, was 180% higher than the 2019 maximum.

In 2018 TN concentrations were: • 2018 TN Surface Mean 0.567 mg/L • 2018 TN Bottom Mean 0.745 mg/L • 2018 TN Surface Median 0.350 mg/L • 2018 TN Bottom Median 0.655 mg/L • 2018 TN Surface Std Dev 0.398 mg/L • 2018 TN Bottom Std Dev 0.305 mg/

2018 Offutt Lake - Total Nitrogen 3.00

2.50

2.00

1.50

mg/L 1.00

0.50

0.00 May June July August September October Surface TN Bottom TN

Figure 17. Concentration of Total Nitrogen at the surface and bottom at OF1 in 2018.

In 2019, TN concentrations were: • 2019 TN Surface Mean 0.373 mg/L • 2019 TN Bottom Mean 0.897 mg/L • 2019 TN Surface Median 0.397 mg/L • 2019 TN Bottom Median 0.725 mg/L • 2019 TN Surface Std Dev 0.107 mg/L • 2019 TN Bottom Std Dev 0.720 mg/L

2019 Offutt Lake - Total Nitrogen 3.00

2.50

2.00

1.50 mg/L 1.00

0.50

0.00 May June July August September October Surface TN Bottom TN

Figure 18. Concentration of Total Nitrogen at the surface and bottom at OF1 in 2019.

The median surface TN was higher in 2019. The total nitrogen concentration was higher at the bottom during stratification because the hypolimnion was hypoxic; ammonia-nitrogen was released from the bottom sediments

14 Offutt Lake 2018 and 2019 and accumulated in the hypolimnion. In September 2019, the anoxic bottom layer had not yet mixed with the rest of the water column and the TN concentration peaked.

Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 19 shows the TN to TP ratio at OF1. Offutt Lake was phosphorus limited in 2018 and 2019.

Offutt Lake - TN to TP Ratio 100

Phosphorus Limited

10 TN:TP (mg/L) Nitrogen Limited

1 2018 2019 Surface TN:TP

Figure 19. TN:TP at OF1 in 2018 and 2019.

Trophic State Indices (TSI)

Table 3. Trophic State Index variables. TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

For OF1, the TSI results were: • 2018 Chlorophyll-a: 59 eutrophic • 2019 Chlorophyll-a: 47 mesotrophic • 2018 Total Phosphorus: 52 eutrophic • 2019 Total Phosphorus: 53 eutrophic • 2018 Secchi Disk: 45 mesotrophic • 2019 Secchi Disk: 45 mesotrophic

Offutt Lake was categorized as: • Eutrophic in 2018: Average TSI 52 • Mesotrophic in 2019: Average TSI 48

15 Offutt Lake 2018 and 2019 Offutt Lake - Trophic State Indices 65 60 55 Eutrophic 50 45 Mesotrophic 40

Oligotrophic TSI ValueTSI 35 30 25 20 2018 2019 Chlorophyll-a TSI TP TSI Secchi TSI Figure 20. OF1 Trophic State Index in 2018 and 2019.

SUMMARY

Thermal Stratification In both 2018 and 2019, the water column at Offutt Lake began to stratify in May and three distinct layers were apparent from June to August. In September 2018, Offutt Lake turned over. In 2019, the upper three-quarters of the water column had mixed in September, and the lake completely turned-over by October.

Transparency In 2018, the mean transparency was 2.9 meters (range from 0.8 to 3.9 meters), and was negatively correlated to the concentration of chlorophyll-a. In 2019, the mean transparency was 2.7 meters (range 1.8 to 3.4 meters). Transparency was not correlated to productivity.

Chlorophyll-a and Lower Productivity Trends In 2018, the mean concentration of chlorophyll-a was 18.7 µg/L (range 2.9 to 80.0 µg/L). In 2019, the mean chlorophyll-a concentration was 5.3 µg/L (range 3.5 to 6.7 µg/L). In both years, the highest productivity occurred in September. Algal blooms with surface scum were reported in May, July, September, and October 2018. During these blooms, TCEH collected five samples which were tested algal toxins. None of the samples exceeded the Washington State Toxic Algae Advisory Level for microcystin, anatoxin-a, cylindrospermopsin, or saxitoxin. No samples for algal toxins were collected in 2019.

Nutrients and Trends The average surface TP concentration was 0.028 mg/L in 2018 and 0.030 mg/L in 2019. This level of TP was above the action level (0.020 mg/L) for lower mesotrophic lakes in the Puget Sound Lowlands ecoregion.

In 2018, the average surface TN concentration was 0.567 mg/L (range 0.279 to 1.390 mg/L). Surface TN increased over 100% in September 2018 when the lake turned over. In 2019, the mean surface TN concentration was lower (0.373 mg/L, range 0.159 to 0.489 mg/L) and lacked the dramatic increase after turnover like in 2018.

Lake Classifications Based on an average of the three TSI variables, the Offutt Lake site OF1 was classified as • eutrophic in 2018 • mesotrophic in 2019

16 Offutt Lake 2018 and 2019 DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 or https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 or https://www.co.thurston.wa.us/health/ehrp/annualreport.html

For digital data contact: [email protected]

For correction, questions, and suggestions, contact the author of the 2018 report: [email protected]

FUNDING SOURCE:

Thurston County funded monitoring in 2018.

LITERATURE CITED

Bortleson, G.C., Dion, N.P., McConnell, J.B., and Nelson, L.M. 1976. Reconnaissance data on lakes in Washington, Volume 4. Water Supply Bulletin 43(4) 161-163.

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Couto, A. and Caromile, S.J. 2007. Four lakes surveyed in fall 2003: McIntosh lake, Munn lake, and Offutt lake in Thurston county and Ohop lake in Pierce county. Washington Department of Fish and Wildlife, Fish Program. FPT 07-03.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

Thurston County Environmental Health (TCEH), 2009. Surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring.

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

17 Offutt Lake 2018 and 2019

Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control Appendix C. Correlation Transparency to Productivity

18 Offutt Lake 2018 and 2019

Appendix A. Raw data

Table A-1 Raw data collected at the Offutt Lake site OF1 in 2018. Bottom Bottom Secchi Water Sample Surface TP Bottom TP Surface TN Bottom TN Chl a Phae a Date Time Depth (meters) Color Depth (mg/L) (mg/L) (mg/L) (mg/L) (µg/L) (µg/L) (meters) (meters)

5/23/2018 10:44 6.50 3.60 8 6.0 0.012 0.017 0.359 0.429 2.9 0.2 6/27/2018 11:07 7.30 3.43 2 6.8 0.012 0.505 0.280 0.562 3.0 <0.1 7/18/2018 13:10 7.60 3.40 4 7.0 0.016 0.178 0.340 0.798 6.7 0.6 8/15/2018 11:09 6.60 3.90 6 6.0 0.010 0.374 0.279 0.777 3.5 0.3 8/15/2018 0.010 0.347 0.329 0.698 3.7 <0.1 QA 11:09 - - - - 9/19/2018 11:45 5.65 0.75 4 5.0 0.065 0.068 1.390 1.370 80.0 2.1 10/24/2018 10:44 5.92 2.13 7 5.4 0.051 0.040 0.730 0.573 16.0 1.9

Table A-2 Raw data collected at the Offutt Lake site OF1 in 2019. Bottom Bottom Secchi Water Sample Surface TP Bottom TP Surface TN Bottom TN Chl a Phae a Date Time Depth (meters) Color Depth (mg/L) (mg/L) (mg/L) (mg/L) (µg/L) (µg/L) (meters) (meters)

5/22/2019 9:27 7.47 3.40 7 7.0 0.014 0.038 0.159 0.192 6.1 <0.1 6/19/2019 9:48 6.73 2.00 7 5.5 0.016 0.174 0.408 0.542 5.7 1.0 7/24/2019 9:59 6.55 3.00 7 6.25 0.029 0.327 0.489 0.922 3.5 1.9 8/27/2019 9:39 6.41 2.82 3 6.0 0.027 0.436 0.341 0.908 5.1 1.5 9/24/2019 9:57 6.91 1.78 10 6.5 0.057 0.835 0.457 2.400 6.7 2.9 10/22/2019 9:49 6.33 3.41 7 6.0 0.034 0.040 0.386 0.418 4.5 1.3

19 Offutt Lake 2018 and 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift for Offutt Lake sample days in 2018. Percent Percent Percent Difference Difference Difference End Date SPC ODO pH (µS/cm) (% sat) (std units) 5/23/2018 -6.13 0.14 -0.29 6/28/2018 0.02 -0.46 0.57 7/18/2018 0.06 0.83 -1.71 8/15/2018 0.18 -0.20 -1.00 10/1/2018 0.09 -0.30 -0.86 10/29/2018 0.98 -0.67 -0.14 Mean Percent Difference -0.80 -0.11 -0.57

Table B-2. Instrument drift for Offutt Lake sample days in 2019. Percent Percent Percent Difference Difference Difference End Date SPC ODO pH (µS/cm) (% sat) (std units) 5/23/2019 -0.71 -0.03 0.14 6/20/2019 -0.18 0.05 0.57 7/26/2019 -0.62 0.09 -0.43 8/28/2019 0.11 -0.30 0.00 9/25/2019 0.20 -0.24 0.00 10/23/2019 0.76 0.16 -0.14

Mean Percent Difference -0.07 -0.04 0.02

20 Offutt Lake 2018 and 2019

Table B-3 Replicate precision for samples collected at the Offutt Lake site OF1 in 2018. Relative Percent Site Datetime sample field replicate Difference OF1 Surface TP 8/15/2018 11:09 0.010 0.010 0.000 OF1 Bottom TP 8/15/2018 11:09 0.374 0.347 7.490 Relative Standard Deviation TP samples: 3.64 OF1 Surface TN 8/15/2018 11:09 0.279 0.329 16.447 OF1 Bottom TN 8/15/2018 11:09 0.777 0.698 10.712 Relative Standard Deviation TN samples: 6.19 OF1 Chlor-a 8/15/2018 11:09 3.50 3.70 5.556 Relative Standard Deviation Chlor-a samples: 2.78 OF1 Phaeo-a 8/15/2018 11:09 0.30 0.10 100.000 Relative Standard Deviation Phae-a samples: 50.00

21 Offutt Lake 2018 and 2019

Appendix C. Correlation Transparency to Productivity

2018 Correlation Transparency to Productivity

90 80 70 y = -23.537x + 86.214 R² = 0.8647 60 µg/L)

a ( 50 - 40 30 20 Chloropyll 10 0 -100.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 Secchi Depth

Figure C-1. Correlation between transparency and productivity in 2018.

2019 Correlation Transparency to Productivity

8 7 6

µg/L 5 a ( - 4 y = -0.8787x + 7.6698 3 R² = 0.2808 2

Chlorophyll 1 0 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00

Secchi Depth

Figure C-2. Correlation between transparency and productivity in 2019.

2019 Summit Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Summit Lake map showing location of sample site SL1 and 456 parcels along the shoreline.

PART OF TOTTEN INLET WATERSHED public boat launch; three small private community accesses; 126-acre boy scout camp • SHORELINE LENGTH: 5.6 miles at the west end of the lake. • LAKE SIZE: 0.8 square miles (530 acres) • BASIN SIZE: 3.8 square miles GENERAL TOPOGRAPHY: • MEAN DEPTH: 16.2 meters (53 feet) The approximate altitude of the lake is 460 • MAXIMUM DEPTH: 30 meters (100 feet) feet. The drainage is steep and rugged with • VOLUME: 5,695,00 cubic meters (4,617 slopes up to 80 percent. There are numerous acre-feet) springs and intermittent streams that flow into the lake. The outlet, at the west end of the PRIMARY LAND USES: lake, is controlled by flash boards and flows Most of the basin is commercial forest with into Kennedy Creek. dense development upslope of the lake or along the shoreline (Figure 1). GENERAL WATER QUALITY: Good to Excellent - The lake has low nutrient PRIMARY LAKE USE: and chlorophyll-a levels and good water clarity. Domestic water supply, fishing, boating, Good water quality is important because the swimming, and other water sports. lake is used as a drinking water source for most of the lake residents. PUBLIC ACCESS: Washington Department of Fish and Wildlife Summit Lake 2019 DESCRIPTION

Summit Lake is in the northwestern corner of Thurston County, about eight miles west of McCleary and nine miles west of Olympia, Washington. One of the deepest lakes in Thurston County, the maximum depth is 30 meters. It is fed by intermittent streams, seeps, and springs. The outlet is Kennedy Creek, which flows north to discharge into Totten Inlet. Many residents depend on the lake for drinking water.

The Department of Fish and Wildlife manage the lake for rainbow trout and kokanee. Summit Lake also supports naturally reproducing largemouth bass, smallmouth bass, yellow perch, brown bullhead, pumpkinseed sunfish, coastal cutthroat and northern pike minnow.

METHODS

In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Summit Lake from May to October. Figure 1 shows the sample site SL1 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 color of the lake water 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 • Dissolved Oxygen (mg/L) YSI EXO1 Multi- ~ 0.5 meter below the water surface to Water Quality • pH (standard units) parameter Sonde ~ 0.5 meter above the bottom sediments Profile • 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 Total Grab Samples with Surface Sample: ~ 0.5 meter below the surface mg/L Nitrogen Kemmerer Bottom Sample: ~ 0.5 meter above the benthos Composite of Chlorophyll-a µg/L Multiple Grab Photic Zone Samples Composite of Phaeophytin- µg/L Multiple Grab Photic Zone a Samples

Figure 2. TCEH compared color of the lake’s water to the Custer Color Strip.

2 Summit Lake 2019 Quality Assurance and Quality Control (QA/QC)

Each sample day 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. General weather conditions from the NOAA Olympia Regional weather station and precipitation from Thurston County 69u Summit Lake weather station.

Table 2. Weather on sample days and the average, minimum, and maximum air temperatures for each month. Monthly Weather Total Precipitation Month Weather on Sample Day Temperature (°C) Previous Seven Days Mean (Low/High)

May Cloudy (12°C); 0-8 mph SSW wind 13 (2/30) 1.30 inches

June Cloudy (19°C); 0-6 mph S wind 15 (4/33) 0 inches

July Cloudy, (21°C); 0-8 mph WSW wind 17 (9/31) 0.5 inches

August Fair, (23°C); 0-13 mph NE wind 21 (12/34) 0.01 inches

September Rain (16°C); 0-8 mph S wind 17 (9/29) 1.14 inches

October Rain (12°C); 0-17 mph SSW wind 12 (6/22) 5.68 inches

Vertical Water Quality Profiles

The vertical water quality profiles illustrate how the water column at Summit Lake was thermally stratified from May until October (Figures 3 to 5). Warmer, more oxygenated water existed on the surface in the epilimnion. Below this layer, the temperature and oxygen concentration declined with depth.

3 Summit Lake 2019 Summit Lake - May 20, 2019 Summit 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 2 2 4 4 6 6 8 8 10 10 12 12 14 14 16 16

18 Depth (meters) 18 Depth (meters) 20 20 22 22 24 24 26 26 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 SPC (µS/cm) SPC µS/cm

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 3. Vertical water quality profiles for Summit Lake collected during May and June 2019.

In May, the lake was stratified. The epilimnion was very distinct; water quality was uniform in the upper 5.5 meters. • May Epilimnion – Mean Temperature 16.17°C; Mean DO 9.90 mg/L; pH 8.42 • May Hypolimnion – Mean Temperature 6.93°C; Mean DO 8.75 mg/L; pH 7.38

In June, the surface water warmed over 3°C. DO and pH were lower than in May. In contrast, temperature and DO in the hypolimnion were greater in June than in May. • June Epilimnion – Mean Temperature 19.87°C; Mean DO 9.10 mg/L; pH 7.53 • June Hypolimnion – Mean Temperature 7.44°C; Mean DO 7.78 mg/L; pH 6.62

During both months, the DO profile exhibited a positive heterograde curve. The water column was sufficiently transparent to permit photosynthesis in the metalimnion. Excess oxygen accumulated there because thermal stratification prevented vertical mixing of the water column (Wetzel, 1983). In May, transparency was very high (11.0 meters), which allowed photosynthesis at greater depth. Productivity was twice as high in May compared to June. DO accrued in upper metalimnion. In June, transparency was reduced to 9.7 meters and productivity declined. The DO supply was lower in the metalimnion and was more concentrated in the deeper, colder water.

4 Summit Lake 2019 Summit Lake - July 23, 2019 Summit 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 2 2 4 4 6 6 8 8 10 10 12 12 14 14 16 16 18 Depth (meters) 18 Depth (meters) 20 20 22 22 24 24 26 26 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70

SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 4. Vertical water quality profiles for Summit Lake collected during July and August 2019.

In July, surface water temperature grew by 1.5°C. DO and pH increased slightly as productivity increased. Transparency fell to 6.5 meters depth. • July Epilimnion – Mean Temperature 21.26°C; Mean DO 9.21 mg/L; pH 7.71 • July Hypolimnion – Mean Temperature 7.84°C; Mean DO 5.88 mg/L; pH 6.25

In August, the epilimnion remained the same temperature. The hypolimnion grew warmer, as DO and pH declined. • August Epilimnion – Mean Temperature 21.26°C; Mean DO 9.17 mg/L; pH 7.66 • August Hypolimnion – Mean Temperature 8.08°C; Mean DO 2.78 mg/L; pH 6.19

During July and August, the DO curve remained positive heterograde. Secchi depth declined these two months compared to early summer. The pH curve indicates primary productivity was limited to the epilimnion.

5 Summit Lake 2019 Summit Lake - September 23, Summit Lake - October 21, 2019 2019 Temperature (°C), pH, DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0 2 2 4 4 6 6 8 8 10 10 12 12 14 14 Depth (meters)

16 Depth (meters) 16 18 18 20 20 22 22 24 24 26 26 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 5. Vertical water quality profiles from Summit Lake collected during September and October 2018.

In September, the temperature of the epilimnion dropped by 2.3°C. This cooler water sank. The epilimnion grew deeper to 9.5 meters. Productivity peaked and transparency fell to 5.9 meters depth. At the bottom of the lake, temperature increased slightly and DO and pH continued to fall. • September Epilimnion – Mean Temperature 18.95°C; Mean DO 9.12 mg/L; pH 7.58 • September Hypolimnion – Mean Temperature 8.17°C; Mean DO 1.54 mg/L; 6.09

The epilimnion continued to cool and sink to 14.5 meters depth in October, but the lake had not yet completely turned over. Productivity remained relatively high and transparency fell to 5.6 meters depth. The DO curve was clinograde. Photosynthesis and contact with the atmosphere oxygenated the epilimnion. Oxygen consuming processes or advection of low oxygen groundwater produced anoxic conditions in the hypolimnion. • October Epilimnion – Mean Temperature 13.87°C; Mean DO 9.52 mg/L; pH 7.27 • October Hypolimnion – Mean Temperature 8.47°C; Mean DO 1.47 mg/L; pH 6.31

Color and Transparency

Color can reveal information about a lake’s nutrient load, algal growth, water quality and surrounding landscape. High concentrations of algae cause the color of the lake’s water to appear green, golden, or red. Weather, rocks and soil, land use practices, and types of trees and plants influence dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown.

Summit Lake Secchi Depth May June July August September October 0.00 2.5

2.00 2.0 4.00 a (µg/L)

1.5 - 6.00 1.0 8.00 Chlorophyll Secchi depth (meters) 10.00 0.5

12.00 0.0

Secchi depth (m) Chlor-a

Figure 6. Secchi depth, chlorophyll-a concentration, and color of the lake water at SL1 in 2019.

The transparency 2019 statistics are: • mean 7.7 • minimum 5.6 in October • median 6.9 • maximum 11.0 in May • standard deviation 2.2

The color of the water, based on the reference Custer Color Strip, was #4 in May and #1 from June to October. Transparency was weakly associated (R² = 0.32) with chlorophyll-a concentration.

Figure 7 shows the annual average transparency (Secchi depth) compared to the long-term average (LTA). Positive values reflect transparency better than the long-term average. In 2019, transparency at Summit Lake was higher (0.9 meter) than the long-term average.

Summit Lake Transparency (meters) Annual Average Minus Long-Term Average 1.5

1.0

0.5

LTA0.0 6.8 -0.5

-1.0

-1.5

Figure 7. Transparency at SL1 compared to the long-term average (LTA).

7 Summit Lake 2019 Productivity

Pigments

2019 Productivity Data

Figures 8 shows that the highest concentration of chlorophyll-a in 2019 occurred in September, and October. The supply of oxygen at the surface was highest in May (9.9 mg/L) and October (9.5 mg/L). The ratio of chlorophyll-a to phaeophytin-a peaked in September. The chlorophyll-a statistics for 2019 are (µg/L): • mean 1.2 • minimum 0.5 in June • median 1.1 • maximum 2.1 in September • standard deviation 0.5

Summit Lake - Chlorophyll-a, Ratio Chlorophyll-a to Phaeophytin-a, and DO 3 25

2 15 µg/L) a ( -

10 µg/L) and DO (mg/L)

1 a (

5 Chlorophyll

0 0 - Phaeophytin May June July August September October

Chlorophyll-a Ratio Chlor-a : Phaeo-a Surface DO

Figure 8. Chlorophyll-a concentration and ratio of chlorophyll-a to phaeophytin-a pigments in samples collected at SL1.

In 2019, TCEH sampled Summit Lake for toxic algae ten times, in the following months: January, February, March (3 samples), April (4 samples) and May. The concentration of anatoxin-a exceeded the Thurston County and Washington State advisory levels in one sample collected April 8, 2019 (Appendix C).

8 Summit Lake 2019 Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998) Figure 9 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at Summit Lake.

Summit Lake - 2019 Surface Total Phosphorus & Total Nitrogen 0.300 0.012

0.250 0.010

0.200 0.008

0.150 0.006 TN (mg/L) TP (mg/L) TP

0.100 0.004

0.050 0.002

0.000 0.000 May June July August September October Surface TN Surface TP

Figure 9. 2019 surface concentration of TP and TN at SL1 at Summit Lake.

The concentration of TP in surface waters was highest from August to October. TN was highest in June and July before higher productivity started in August. Thermal stratification reduced internal loading to surface waters from May to October; changes in the phytoplankton community and external sources likely affect nutrient levels during stratification.

Total Phosphorus

9 Summit Lake 2019 Summit Lake - 2019 Total Phosphorus

0.20 0.18 0.16 0.14 0.12 0.10

mg/L 0.08 Action Level 0.06 0.020 mg/L 0.04 0.02 0.00 May June July August September October Surface TP Bottom TP

Figure 10. Concentration of Total Phosphorus at the surface and bottom at SL1 in 2019.

At SL1, the 2019 statistics for TP concentration are (mg/L): • Surface mean 0.007 • Bottom mean 0.062 • Surface median 0.008 • Bottom median 0.030 • Surface standard deviation 0.003 • Bottom standard deviation 0.060 • Surface minimum 0.002 in June • Bottom minimum 0.012 in June • Surface maximum 0.011 in October • Bottom maximum 0.173 in October

The concentration was greater at the bottom because Summit Lake was thermally stratified during the summer. During stratification, the hypolimnion was mostly stagnant, not mixing with the oxygenated water above. Meanwhile, oxygen in the hypolimnion was consumed by redox processes like decomposition and advection of low DO groundwater. Due to the lack of oxygen near the bottom, phosphorus stored in the sediments was released into the water column. This phosphorus accumulated in the hypolimnion, until turn-over later.

TCEH has collected data at Summit Lake since 2008. The statistics for the twelve-year period of record are (mg/L): • Surface mean 0.006 • Bottom mean 0.036 • Surface median 0.006 • Bottom median 0.020 • Surface standard deviation 0.001 • Bottom standard deviation 0.012 • Surface minimum mean 0.005 in 2008 • Bottom minimum mean 0.012 in 2009 • Surface maximum mean 0.008 in 2009 • Bottom maximum mean 0.176 in 2018

10 Summit Lake 2019 Figure 11 displays the average annual concentration of total phosphorus at Summit Lake from 2008 to 2019 The surface samples for total phosphorus have been below the state action level (purple line at 0.020 mg/L) for the entire of the period of record.

Summit Lake - Total Phosphorus Annual Summer Averages 0.20

0.16

0.12 mg/L 0.08 Action Level 0.020 mg/L 0.04

0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Bottom TP Surface TP

Figure 11. Average Annual Total Phosphorus at SL1 from 2008 to 2019.

Nitrogen

Nitrogen is also limiting to lake productivity, but supplies are more readily augmented by inputs from external sources. The State of Washington does not have established action or cleanup levels for surface total nitrogen. At SL1, the 2019 statistics for TN concentration are (mg/L): • Surface mean 0.143 • Bottom mean 0.286 • Surface median 0.130 • Bottom median 0.310 • Surface standard deviation 0.079 • Bottom standard deviation 0.057 • Surface minimum 0.026 in October • Bottom minimum 0.188 in August • Surface maximum 0.284 in July • Bottom maximum 0.340 in July

The TN concentration statistics for the 2008 to 2019 period of record are (mg/L): • Surface mean 0.163 • Bottom mean 0.286 • Surface median 0.153 • Bottom median 0.252 • Surface standard deviation 0.033 • Bottom standard deviation 0.167 • Surface minimum mean 0.116 in 2011 • Bottom minimum mean 0.157 in 2011 • Surface maximum mean 0.231 in 2016 • Bottom maximum mean 0.794 in 2018

The total nitrogen concentration was higher at the bottom because the hypolimnion was hypoxic during stratification; ammonia-nitrogen was released from the bottom sediments and accumulated in the hypolimnion. Figure 12 shows the 2019 TN concentrations at the surface and bottom of Summit Lake at SL1. Figures 13 displays the average annual concentrations for total nitrogen from 2008 to 2019.

11 Summit Lake 2019

Summit Lake - 2019 Total Nitrogen 0.4

0.3

0.2 mg/L

0.1

0.0 May June July August September October

Surface TN Bottom TN

Figure 12. Concentration of Total Nitrogen at the surface and bottom at SL1 in 2019.

Summit Lake - Total Nitrogen Annual Summer Averages 0.90 0.80 0.70 0.60 0.50

mg/L 0.40 0.30 0.20 0.10 0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN Bottom TN Figure 13. Average Annual Total Nitrogen at SL1 from 2008 to 2019.

12 Summit Lake 2019 Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 14 shows the TN to TP ratio at the Summit Lake site, which has been phosphorus limited since 2008.

Summit Lake - TN to TP Ratio 100 Phosphorus Limited

Nitrogen Limited TN:TP (mg/L)

1 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN:TP

Figure 14. TN:TP at SL1 from 2008 to 2019.

Trophic State Indices (TSI)

For Summit Lake at SL1, the 2019 TSI results are: • Chlorophyll-a: 32 oligotrophic • Total Phosphorus: 32 oligotrophic • Secchi Disk: 31 oligotrophic

The average of the three TSI variables is 32, which categorizes Summit Lake as oligotrophic in 2019. Based on the TP concentration and Secchi depth, Summit Lake has been classified as oligotrophic since 2008 (Figure 20). In 2010, the TSI score for chlorophyll-a concentration entered the mesotrophic range with a score of 42.

13 Summit Lake 2019 Summit Lake - Trophic State Indices 60 55 Eutrophic 50 45 Mesotrophic 40 35 TSI ValueTSI 30 25 Oligotrophic 20 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Chlorophyll-a TSI TP TSI Secchi TSI Figure 6. SL1 Trophic State Index from 2008 to 2019.

SUMMARY

Thermal Stratification from May to October 2019 In 2019, the water column at Summit Lake was thermally stratified from May to October. The DO curve was positive heterograde from May to August. The water column was transparent, and photosynthesis occurred in the metalimnion where excess oxygen accumulated. In September and October, the DO curve changed to clinograde. The epilimnion was oxygenated due to photosynthesis and contact with the atmosphere. The hypolimnion was anoxic due to redox processes and advection of low oxygen groundwater.

Good Transparency in 2019 In 2019, the mean transparency was 7.7 meters, 0.9 meters higher than the long-term average. Transparency was weakly associated (R² = 0.32) with chlorophyll-a concentration.

Chlorophyll-a Concentration and Low Productivity In 2019, the mean concentration of chlorophyll-a was 1.1 µg/L (range 0.5 to 2.1 µg/L). Productivity was relatively low. The highest productivity was in September and October.

TCEH sampled Summit Lake ten times for toxic algae in 2019, detecting toxins over the Thurston County and Washington State advisory levels one time for anatoxin-a in April.

Nutrients Enrichment Stable In 2019, the average TP concentration was 0.007 mg/L at the surface, below the action level (0.020 mg/L) for lower mesotrophic lakes in the Puget Sound Lowlands ecoregion. The mean surface TN concentration was 0.163 mg/L in 2019, approximately the same as the long-term (2008 to 2018) mean (0.164 mg/L).

Classified as Oligotrophic In 2019, the Summit Lake site SL1 was classified as oligotrophic based on an average of the three TSI variables.

Summit Lake 2019

DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 or https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 or https://www.co.thurston.wa.us/health/ehrp/annualreport.html For digital data, contact [email protected] For question, suggestions, or concerns, contact the author of this report [email protected]

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

TCEH. 2009. Surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring.

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

15 Summit Lake 2019

Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control Appendix C. Toxic Algae

16 Summit Lake 2019

Appendix A. Raw data

Table A-1 Raw data collected at the Summit Lake site SL1 in 2019. Profile Samples Site INFO Temp ( C ) pH DO (m/l) Conductivity (Sp) Turb (FNU) TP TN Composite Sample Bottom Bottom Total Secchi Water Profile Sample Site Date Time Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a (m) Color Depth Depth (m) (m) (m) Summit 5/20/2019 13:40 27.4 11.00 4 24.5 16.173 6.941 8.50 7.35 9.92 8.68 58.0 57.4 -0.55 -0.29 25.5 0.006 0.110 0.100 0.311 1.1 <0.1 Summit 6/17/2019 13:25 25.1 9.67 1 24.5 20.201 7.440 7.56 6.59 9.05 7.73 59.6 58.0 -1.23 -0.84 24.5 0.002 0.012 0.185 0.309 0.5 <0.1 Summit 7/23/2019 14:27 25.2 6.50 1 24.5 21.367 7.829 7.78 6.23 9.24 5.78 59.5 58.3 -24.85 -23.70 25 0.005 0.016 0.284 0.340 0.9 0.1 Summit 8/26/2019 13:17 24.95 7.30 1 24.5 21.483 8.043 7.67 6.17 9.18 2.23 60.4 60.7 0.22 5.71 24.5 0.009 0.018 0.128 0.188 1.1 0.4 Summit 9/23/2019 12:24 24.9 5.90 1 13.5 18.940 13.589 7.66 6.78 9.17 8.27 60.0 58.2 -0.32 -0.22 24.5 0.009 0.041 0.132 0.232 2.1 <0.1 Summit 10/21/2019 13:26 24.7 5.60 1 24.0 13.890 8.159 7.43 6.20 9.62 0.63 59.8 70.5 0.44 5.16 24.10 0.011 0.173 0.026 0.337 1.4 0.7

17 Summit Lake 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

18 Summit Lake 2019

19 Summit Lake 2019

Appendix C. Algal toxins

cylindrospermopsin microcystin and saxitoxin anatoxin-a

Figure C-1. Concentration of four algal toxins at Summit Lake from 2012 to 2019.

Figure C-1 shows the concentration (µg/L) of algae toxins from Summit Lake samples and the 2019 drinking water advisory levels:

• anatoxin-a - 1.0 µg/L child and adult • microcystin and saxitoxin - 0.3 µg/L child to 1.6 µg/L adult • cylindrospermopsin - 0.7 µg/L child to 3 µg/L adult

2019 Ward Lake Water Quality Report Prepared by Thurston County Environmental Health Division

Figure 1. Ward Lake map showing location of sample site WD1.

PART OF DESCHUTES RIVER WATERSHED private access points exist for lakeside communities. • SHORELINE LENGTH: 1.4 miles • LAKE SIZE: 0.1 square miles (65 acres) GENERAL TOPOGRAPHY: • BASIN SIZE: 0.95 square miles The Ward Lake sub-basin is 313 acres. The lake • MEAN DEPTH: 10 meters (33 feet) is located at an altitude of 131 feet above mean • MAXIMUM DEPTH: 20 meters (67 feet) sea level. The topography of the basin is • VOLUME: 2,100 acre-feet lowlands and rolling hills with occasional glacial depressions. Ward Lake is a kettle lake, a deep PRIMARY LAND USES: glacial depression, that is fed by groundwater. Most of the basin is suburban with moderate to There is no surface inlet or outlet. high density residential housing. Historically

there was a large plant nursery on the west 2019 GENERAL WATER QUALITY: side, but that area is now apartments and Good – Ward Lake was classified as oligotrophic single-family homes. in 2019. Chlorophyll-a concentration was PRIMARY LAKE USE: relatively low. Transparency was good, except Ward Lake is used for fishing, boating, and in July. The total phosphorus (TP) swimming. concentration was below the action level. Two algal blooms were reported in January and PUBLIC ACCESS: March, but no toxins were detected. The Washington Department of Fish and Wildlife has one public boat launch. Four Ward Lake 2019

DESCRIPTION

Ward Lake is a kettle lake located near the southwest boundary of Olympia, Washington. In the Puget Sound lowlands, many lakes occupy depressions in the surface of glacial drift. Ward Lake was formed by the melting of huge blocks of glacial ice. Kettle lakes often have a crenulated shoreline and undulating bathymetry. Ward Lake and the surrounding drainage area have Yelm fine sandy loam soils. Formed by volcanic ash and glacial outwash, these are deep, moderately drained soils on terraces (USDA, 1990).

Much of the eastern shoreline has been developed for residential use, with docks, bulkheads, and maintained lawns extending to the edge of water. Other shorelines are less developed, with more native riparian vegetation, wetlands, and large woody debris (Herrera, 2011).

Aquatic macrophytes in the littoral zone include fragrant water lily (non-native and invasive), yellow water lily, Nuttall’s waterweed, water moss, and big-leaf pondweed. Emergent plants grow along the shoreline, including bull rush, cattail, and yellow flag iris (non-native and invasive).

Ward Lake is fed by groundwater; it has no surface inlet or outlet. Water quality has been generally good, except for in 2012 when higher concentrations of nutrients and fecal coliform bacteria degraded water quality and spring and summer algal blooms interfered with recreation.

The Department of Fish and Wildlife manage the lake for rainbow trout and kokanee. Ward Lake also supports naturally reproducing largemouth bass, bluegill sunfish, cutthroat trout, and rock bass. Ward Lake is listed for persistent organic pollutants in fish: Category 5 (highest category for polluted waters) for Polychlorinated Biphenyls (PCBs) and Category 2 (water of concern) for 2, 3, 7, 8-Tetrachlordibenzo-p-dioxin (TCDD), which is the most toxic dioxin. Ward Lake was listed for these contaminants in 2006 as a result of a toxin study of tissue samples from bluegill, kokanee, and largemouth bass.

METHODS

In 2019, Thurston County Environmental Health (TCEH) conducted monthly monitoring at Ward Lake from May to October. Figure 1 shows the Ward Lake sample site WD1 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 color of the water since the 1990s.

Ward Lake 2019

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) Grab Samples with Surface Sample: ~ 0.5 meter below the surface Total Phosphorus mg/L 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

Figure 2. TCEH compared water color to the Custer Color Strip.

Quality Assurance and Quality Control (QA/QC)

RESULTS

Weather Conditions

Weather conditions during the 2019 sample season are provided in Table 2.

Ward Lake 2019 Table 2. Weather from NOAA Regional Weather Station on 2019 sample days and the average, minimum, and maximum air temperatures for each month. Temperature (ᵒ C) Month Weather on Sample Day Monthly Average (Low/High) May Cloudy, 16°C, ENE Winds 0-6 mph 13 (2/29) June Cloudy, 18°C, Var Winds 0-5 mph 15 (4/33) July Fair, 28°C, N Winds 0-7 mph 18 (8/32) August Fair, 28°C, NE Winds 0-7 mph 18 (7/33) September Fair, 20°C, Var Winds 0-3 mph 14 (-1/26) October Fair, 8°C, N to NNE Winds 0-9 mph 8 (-5/18)

Vertical Water Quality Profiles

The vertical water quality profiles illustrate how the water column at Ward Lake was thermally stratified for the duration of the sample season (Figures 3 to 5). Warmer, more oxygenated water existed on the surface in the epilimnion. Below this layer, the temperature and oxygen concentration declined with depth.

Ward Lake 2019

Ward Lake - May 21, 2019 Ward Lake - June 18, 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 2 2 4 4 6 6 8 8 10 10 12 12 Depth (meters) 14 Depth (meters) 14 16 16 18 18 20 20 0 20 40 60 80 100 0 20 40 60 80 100 SPC µS/cm SPC µS/cm

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 3. Vertical water quality profiles collected at WD1 in May and June 2019.

Ward Lake was thermally stratified in May. The summer sun heated the surface layer, the epilimnion, to a depth of 3.5 meters. Secchi depth was almost five meters, which permitted photosynthesis in the cooler metalimnion. Productivity peaked in May. The effects of photosynthesis in the upper metalimnion are apparent by the sharp pH and DO increase. The oxygen produced accumulated in the metalimnion, which was not mixing with the upper and lower layers due to density differences during thermal stratification. This type of DO curve is called positive heterograde. • May Epilimnion – Mean Temperature 17.9°C; Mean DO 10.0 mg/L • May Hypolimnion – Mean Temperature 5.3°C; Mean DO 0.7 mg/L

In June, the mean daily temperature increased, warming the surface waters. The epilimnion retained this heat because overnight temperatures were 4°C warmer than in May. The mean temperature increased 3°C. The epilimnion remained about 3.5 meters deep. Water transparency grew to over six meters depth. The concentration of chlorophyll-a was less than half the concentration in May. The DO curve remained a positive heterograde, but the mean DO concentration was lower. • June Epilimnion – Mean Temperature 21.3°C; Mean DO 9.1 mg/L • June Hypolimnion – Mean Temperature 5.5°C; Mean DO 0.7 mg/L

Ward Lake 2019

Ward Lake - July 25, 2019 Ward Lake - August 28, 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 2 2 4 4 6 6 8 8 10 10 12 12 Depth (meters) Depth (meters) 14 14 16 16 18 18 20 20 0 20 40 60 80 0 20 40 60 80 SPC (µS/cm) SPC (µS/cm)

TEMP pH D.O. SPC TEMP pH D.O. SPC

Figure 4. Vertical water quality profiles collected at site WD1 in July and August 2019.

In July, the epilimnion reached the season’s high temperature 23.9°C and its depth increased to 4.5 meters. Transparency fell to the season’s low of three meters. Productivity was somewhat greater in July, compared to June. The pH and DO curves indicate enhanced impacts of photosynthesis from four to eight meters depth. Isolated from the oxygenated strata above, the hypolimnion grew more anoxic due to oxygen consuming processes or advection of low oxygen groundwater • July Epilimnion – Mean Temperature 22.9°C; Mean DO 9.1 mg/L • July Hypolimnion – Mean Temperature 5.8°C; Mean DO 0.6 mg/L

The epilimnion depth remained 4.5 meters deep in August. Compared to July, transparency grew two meters deeper in August. The water changed from green to clear, even though productivity remained about the same (chlorophyll-a concentration was 1.9 µg/L in both July and August). The DO curve remains positive heterograde. The pH curve indicates most of the productivity was close to the surface. • August Epilimnion – Mean Temperature 22.7°C; Mean DO 8.7 mg/L • August Hypolimnion – Mean Temperature 6.1°C; Mean DO 0.7 mg/L

Ward Lake 2019

Ward Lake - September 25, 2019 Ward Lake - October 23, 2019

Temperature (°C), pH, DO (mg/L) Temperature (°C), pH (std), DO (mg/L) 0 5 10 15 20 0 5 10 15 20 0 0 2 2 4 4 6 6 8 8 10 10

Depth (meters) 12 12 14 Depth (meters) 14 16 16 18 18 20 20 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 5. Vertical water quality profiles collected at site WD1 in September and October 2019.

In September, the temperature of the epilimnion declined and this layer extended one meter deeper. The oxygen supply in the metalimnion declined significantly. The lake was clear. Transparency was over 6 meters. The pH curve indicates photosynthesis in the photic zone to six meters depth. The positive heterograde DO curve has weakened to include only the upper meter of the metalimnion. • September Epilimnion – Mean Temperature 19.3°C; Mean DO 8.9 mg/L • September Hypolimnion – Mean Temperature 6.0°C; Mean DO 0.6 mg/L

The epilimnion cooled and sank two meters in October. The DO curve changed to clinograde. The metalimnion was no longer supersaturated with oxygen. Productivity, which declined somewhat compared to September, appeared to be restricted to the epilimnion. Transparency was reduced by one-third to 4.4 meters. The hypolimnion grew colder and deeper in October. • October Epilimnion – Mean Temperature 13.5°C; Mean DO 9.2 mg/L • October Hypolimnion – Mean Temperature 5.9°C; Mean DO 0.6 mg/L

Color and Transparency

Ward Lake 2019 dissolved and suspended materials in the lake. Tannins and lignins, naturally occurring organic compounds from decomposition, can color the water yellow to brown.

Ward Lake - Transparency, Water Color, and Productivity May June July August September October 0.00 3.5

1.00 3.0

2.00 2.5 a (µg/L)

3.00 2.0 -

4.00 1.5

5.00 1.0 Chlorophyll Secchi depth (meters) 6.00 0.5

7.00 0.0 Secchi Depth (meters) Chl a (µg/L)

Figure 6. Color of lake water (bar color), Secchi depth (bar length), and chlorophyll-a concentration (purple line) from May to October 2019.

In 2019, mean transparency was 5.06 meters and median transparency was 5.08 meters, ranging from the high of 6.30 meters in June and September to the low of 3.21 meters in July.

Ward Lake 2019

Figure 7 shows the annual average transparency (Secchi depth) compared to the long-term average (LTA). Positive values reflect transparency better than the long-term average. In 2019, transparency at WD1 was over 0.3 meters higher than the long-term average. Ward Lake - Transparency (meters) Annual Average Minus Long-Term Average (LTA) 1 0.5 LTA 4.70 -0.5 -1 -1.5 -2 -2.5

Figure7. 2019 transparency at WD1 compared to the long-term average (LTA).

The Seasonal Kendall test for 2008 to 2018 revealed a trend of reduced transparency in July and August and increased transparency in May. No significant (p˂0.05) trends existed in June, September, and October (TCEH, 2018).

Productivity

Pigments

Chlorophyll-a pigment is present in algae and cyanobacteria and is widely used to assess the abundance of phytoplankton in suspension. Phaeophytin is also a pigment, but it is not active in photosynthesis. It is a breakdown product of chlorophyll and is present in dead suspended material (Moss, 1967). Phaeophytin absorbs light in the same region of the spectrum as chlorophyll-a, and if present, can interfere with acquiring an accurate chlorophyll-a value. Phaeopigments have been reported to contribute 16 to 60% of the measured chlorophyll-a content (Marker et al., 1980). The ratio of chlorophyll-a to phaeophytin-a has been used as an indicator of the physiological condition of phytoplankton in the sample.

2019 Productivity Data

The chlorophyll-a statistics for 2019: • mean 2.2 µg/L • median 2.0 µg/L • standard deviation 0.6 µg/L

Ward Lake 2019

Figures 8 shows that the concentration of chlorophyll-a, the ratio chlorophyll-a to phaeophytin-a, and the DO supply in the epilimnion peaked in May. Chlorophyll-a concentration declined in June, leveled off in July and August. Productivity increased somewhat in September and October. The chlorophyll-a to phaeophytin-was significantly lower in samples collected later in the season, particularly in samples from August, September, and October.

Ward Lake - 2019 Chlorophyll-a, Ratio Chlorophyll-a to Phaeophytin-a, and DO

4 36 32

3 28 24

µg/L) 20

a ( 2 -

16 µg/L) and DO (mg/L)

12 a ( 1 8 Chlorophyll 4

0 0 - Phaeophytin May June July August September October

Chlorophyll-a Ratio Chlor-a : Phaeo-a Epilimnion Mean DO

Figure 8. Chlorophyll-a concentration, ratio of chlorophyll-a to phaeophytin-a pigments and mean DO in the epilimnion at WD1 in 2019.

In 2019, citizens reported algal blooms at Ward Lake in January, and March. TCEH collected samples on 1/29/2019 and 3/19/2019. King County analyzed both samples for anatoxin-a, cylindrospermopsin, microcystin, and saxitoxin. All results were below the method detection limit for the laboratory method.

Nutrients

Surface Nutrients

Inorganic nutrients, particularly the elements phosphorus and nitrogen, are vital for algal nutrition and cellular constituents. Over-enrichment of surface waters leads to excessive production of autotrophs, especially algae and cyanobacteria (Correll, 1998). Figure 9 shows the total phosphorus (TP) and total nitrogen (TN) present in the surface waters at WD1 in 2019.

Ward Lake 2019

Ward Lake - Surface Total Phosphorus & Total Nitrogen 0.50 0.020

TP Action Level 0.40 0.020 mg/L 0.015

0.30 0.010

0.20 (mg/L) TP TN (mg/L)

0.005 0.10

0.00 0.000 May June July August September October Surface TN Surface TP

Figure 9. Surface concentration of TP and TN at WD1 at Ward Lake in 2019.

Total Phosphorus (TP)

Ward Lake 2019

Ward Lake- Total Phosphorus 1.20

1.00

0.80

0.60 mg/L 0.40

Action Level 0.20 0.020 mg/L

0.00 May June July August September October

Surface TP Bottom TP

Figure 10. Concentration of Total Phosphorus at the surface and bottom of Ward Lake at WD1 in 2019.

At WD1, the 2019 statistic for surface TP concentration are: • TP Surface Mean 0.011 mg/L • TP Bottom Mean 0.906 mg/L • TP Surface Median 0.010 mg/L • TP Bottom Median 0.918 mg/L • TP Surface Std Dev 0.005 mg/L • TP Bottom Std Dev 0.231 mg/L The TP concentration was higher at the bottom because Ward Lake was thermally stratified during the summer. During stratification, the hypolimnion was mostly stagnant, not mixing with the oxygenated water above. At the same time, oxygen in the hypolimnion was consumed by redox processes like decomposition and advection of low DO groundwater. Due to the lack of oxygen near the bottom, phosphorus stored in the sediments was released into the water column. This phosphorus accumulated in the hypolimnion over the course of the sample season.

Figure 11 displays the average annual concentration of TP at the Ward Lake site WD1 from 2008 to 2019. From 2008 to 2019, the statistics for TP concentration are: • TP Surface Mean 0.012 mg/L • TP Bottom Mean 0.280 mg/L • TP Surface Median 0.011 mg/L • TP Bottom Median 0.223 mg/L • TP Surface Std Dev 0.005 mg/L • TP Bottom Std Dev 0.225 mg/L

Ward Lake 2019

Ward Lake - Total Phosphorus Annual Summer Averages 1.00 0.90 0.80 0.70 0.60

mg/L 0.50 0.40 0.30 Action Level 0.020 0.20 mg/L 0.10 0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TP Bottom TP

Figure 11. Average Annual Total Phosphorus (TP) at WD1 from 2008 to 2019.

TCEH has monitored Ward Lake since 2008. For the 12 years, the mean surface TP was below the state action level (purple line at 0.020 mg/L) every sample season except in 2017. The highest mean surface TP was 0.025 mg/L collected in 2017 and the lowest was 0.006 mg/L collected in 2008. The mean TP concentration in the hypolimnion has been trending upward since 2017.

Total Nitrogen

Ward Lake 2019

Ward Lake - Total Nitrogen 5.0

4.0

3.0

2.0 mg/L

1.0

0.0 May June July August September October

Surface TN Bottom TN

Figure 12. Concentration of Total Nitrogen (TN) at the surface and bottom at WD1 in 2019.

The 2019 TN concentration statistics are: • TN Surface Mean 0.363 mg/L • TN Bottom Mean 3.340 mg/L • TN Surface Median 0.312 mg/L • TN Bottom Median 3.435 mg/L • TN Surface Std Dev 0.171 mg/L • TN Bottom Std Dev 0.841 mg/L In 2019, TN at the surface was greatest in mid-summer in June (0.302 mg/L) and July (0.386 mg/L). The lowest concentration was in May (0.146 mg/L). Trend analysis (2008 to 2018) for surface TN revealed significant (p<0.05) trends (TCEH, 2018): • Downward trend in May (0.0.065 mg/L) • Upward trends in June (0.018 mg/L), July (0.066 mg/L) and August (0.033 mg/L) The TN concentration was higher at the bottom because the hypolimnion was hypoxic during stratification; ammonia-nitrogen was released from the bottom sediments and accumulated in the hypolimnion. The highest bottom TN (4.380 mg/L) occurred in September and the lowest (1.870 mg/L) in May.

Figure 13 displays the mean annual concentrations for TN from 2008 to 2019. The surface TN concentration exceeded the mean in 2012 and 2018. The bottom concentration exceeded the mean 2013 and 2018 and 2019.

The statistics for the TN concentration for the period of record are: • TN Surface Mean 0.363 mg/L • TN Bottom Mean 1.361 mg/L • TN Surface Median 0.312 mg/L • TN Bottom Median 1.203 mg/L • TN Surface Std Dev 0.171 mg/L • TN Bottom Std Dev 0.711 mg/L

Ward Lake 2019

Ward Lake - Total Nitrogen Annual Summer Averages 4.00 3.50 3.00 2.50 2.00

mg/L 1.50 1.00 0.50 0.00 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Surface TN Bottom TN

Figure 13. Average Annual Total Nitrogen at WD1 from 2008 to 2019.

Nitrogen to Phosphorus Ratios

To prevent dominance by cyanobacteria (blue-green algae), the TN to TP ratio (TN:TP) should be above 10:1 (Moore and Hicks, 2004). Figure 14 shows the TN to TP ratio at WD1. Ward Lake has been phosphorus limited since 2008.

Ward Lake - TN to TP Ratio 70 60 50 40 30 20 Phosphorus Limited

TN:TP (mg/L) 10 0 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Surface TN:TP

Figure 14. TN:TP at the Ward Lake site WD1 from 2008 to 2019.

Trophic State Indices (TSI)

The most used method to classify lakes is called the Carlson’s Trophic State Index (Carlson, 1977). Based on the productivity, this method uses three index variables: transparency (Secchi disk

Ward Lake 2019 depth), chlorophyll-a (productivity), and phosphorus concentrations (nutrient enrichment). Table 3 provides the index values for each trophic classification. Table 3. Trophic State Index variables. TSI Value Trophic State Productivity 0 to 40 oligotrophic Low 41 to 50 mesotrophic Medium ˃ 50 eutrophic High

For the Ward Lake site, the 2019 TSI results were: • Chlorophyll-a: 38 oligotrophic • Total Phosphorus: 39 oligotrophic • Secchi Disk: 37 oligotrophic The average of the three TSI variables is 38, which categorizes the Ward Lake site as oligotrophic in 2019. Based on the chlorophyll-a concentration, Ward Lake has been mesotrophic 83% of sample seasons -- every year except 2009 and 2019 (Figure 15). The TSI value for total phosphorus classified the Ward Lake site as mesotrophic 25% of sample seasons -- in 2012, 2013, and 2017. For water transparency, the Ward Lake site was classified as oligotrophic 92% of sample seasons; this site was classified as mesotrophic once in 2012 based on reduced water clarity.

Ward Lake - Trophic State Indices 60 55 Eutrophic 50 45 Mesotrophic 40 35 TSI ValueTSI 30 25 Oligotrophic 20 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Chlorophyll-a TSI TP TSI Secchi TSI Figure 15. Ward Lake Trophic State Index from 2008 to 2019.

The Mann Kendall test revealed significant increasing trend (p˂0.05) for the Secchi depth TSI value for the 2008 to 2018 decade. The upward trend of the Secchi depth TSI indicates lower transparency. No trend was found for chlorophyll-a or TP concentration TSI scores (TCEH, 2018).

Ward Lake 2019

SUMMARY

Thermally Stratified from May to October In 2019, the water column at Ward Lake was thermally stratified from May to October. The trend from 2008 to 2018 was increased temperature in surface water at WD1 from May to August (TCEH, 2018).

Good Transparency in 2019 In 2019, the mean transparency was 5.1 meters, over 0.3 meters higher than the long-term average. Transparency in 2019 was highest in June and September (6.3 meters) and lowest in July (3.2 meters). The trend from 2008 to 2018 was more transparency in May and less transparency in July and August (TCEH, 2018).

Lower Chlorophyll-a in 2019 In 2019, the concentration of chlorophyll-a was relatively low (mean 2.2 and median 2.0 µg/L). The highest productivity (3.3 µg/L) was in May and the lowest (1.5 µg/L) was in June. The DO concentration was highest (10.0 mg/L) in May, when productivity peaked. Trend analysis indicates a significant downward trend in June and upward trend in August. The magnitude of the trends was +/- 0.5 µg/L for the decade (TCEH, 2018).

TCEH received reports of algal blooms in January and March 2019. One sample was collected during each bloom. No toxins were detected in these samples.

2019 Nutrients and Trends The 2019 mean surface TP concentration was 0.011 mg/L, below the action level (0.020 mg/L) for lower mesotrophic lakes in the Puget Sound Lowlands ecoregion. In 2019, TP at the surface was highest in June (0.019 mg/L) and lowest in August (0.006 mg/L).

TCEH has monitored Ward Lake since 2008. In those twelve years, the mean surface TP was below the state action level (purple line at 0.020 mg/L) every sample season except in 2017. The mean TP concentration in the hypolimnion has been trending upward since 2017.

The mean surface TN concentration was 0.267 mg/L in 2019. The highest concentration occurred in July (0.386 mg/L) and the lowest in May (0.147 mg/L). The Seasonal Kendall test for surface TN from 2008 to 2018 indicated a significant (p<0.05) downward trend in May and upward trends in June, July, and August (TCEH, 2018).

Classified as Oligotrophic in 2019 In 2019, the Ward Lake was classified as oligotrophic based on an average of the three TSI variables. Since 2008, the TSI value has been in the mesotrophic range: 83% of sample seasons for chlorophyll-a, 25% for TP, and 8% for Secchi depth. The trend for Secchi depth TSI from 2008 to 2018 was upward, which indicates a decline in transparency. There was no trend for chlorophyll-a and TP TSI scores (TCEH, 2018).

Ward Lake 2019

CONTACTS AND DATA SOURCES:

Thurston County Community Planning and Economic Development (360) 786-5549 or https://www.thurstoncountywa.gov/planning/Pages/water-gateway.aspx

Thurston County Environmental Health (360) 867-2626 or https://www.co.thurston.wa.us/health/ehrp/annualreport.html For digital data contact [email protected] For questions, corrections, and/or suggestions, contact the author of the 2019 report: [email protected]

FUNDING SOURCE:

Thurston County funded monitoring in 2019.

LITERATURE CITED

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography. 22(2): 361-369

Correll, D.L. 1998. The role of phosphorus in the eutrophication of receiving waters: a review. Journal of Environmental Quality 27(2): 261-266.

Gilliom, R.J. 1983. Estimation of nonpoint source loadings of phosphorus for lakes in the Puget Sound region, Washington. USGS Water Supply Paper 2240.

Herrera Environmental Consultants, Inc. 2011. Baseline characterization: Ward lake and Ward lake park.

Moore, A. and Hicks, M. 2004. Nutrient criteria development in Washington State. Washington State Department of Ecology, Publication Number: 04-10-033.

Moss, Brian. 1967. Studies on the degradation of chlorophyll-a and carotenoids in freshwaters. New Phytol. 67: 49-59.

TCEH. 2009. Surface water ambient monitoring program: standard operating procedures and analysis methods for water quality monitoring. Thurston County Environmental Health. Olympia, Washington.

Ward Lake 2019

TCEH. 2018. Ward Lake Water Quality Report. Thurston County Environmental Health. Olympia, Washington.

USDA. 1990. Soil survey of Thurston County, Washington.

WAC. 2019. Chapter 173-201A, “Water Quality Standards for Surface Water of the State of Washington.” https://apps.leg.wa.gov/wac/default.aspx?cite=173-201a

Wetzel, R.G. 1983. Limnology, 2nd Edition. CBS College Publishing, New York, NY.

Ward Lake 2019

Appendices

Appendix A. Raw Data Appendix B. Quality Assurance/Quality Control

Ward Lake 2019

Appendix A. Raw Data

Profile Samples Site INFO Temp ( C ) pH DO (m/l) Conductivity (Sp) Turb (FNU) TP TN Composite Sample Bottom Bottom Total Secchi Water Profile Sample Site Date Time Depth Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Surface Bottom Chl a Phae a (m) Color Depth Depth (m) (m) (m) Ward 5/21/2019 12:55 19.2 4.90 2 19.0 18.033 5.406 7.76 6.59 10.01 0.61 22.8 80.5 -0.15 2.48 18.5 0.014 0.633 0.147 1.870 3.3 <0.1 Ward 6/18/2019 13:22 19.15 6.30 6 18.5 21.377 5.477 7.88 6.21 9.13 0.59 22.5 77.6 -1.06 1.05 18.5 0.019 1.100 0.302 3.350 1.5 <0.1 Ward 7/25/2019 14:02 19.15 3.21 6 18.5 23.667 5.577 7.17 6.05 8.95 0.49 22.6 79.9 0.16 2.64 18.5 0.009 0.719 0.386 3.120 1.9 <0.1 Ward 8/28/2019 13:05 19.35 5.25 1 18.5 23.229 5.693 7.58 5.98 8.76 0.56 22.9 72.7 0.28 2.14 18.8 0.006 0.746 0.285 3.520 1.9 0.7 Ward 9/25/2019 14:04 19 6.30 1 18.5 19.959 5.770 7.41 6.00 8.89 0.55 22.9 89.2 1.13 1.94 18.50 0.010 1.090 0.289 4.380 2.4 0.4 Ward 10/23/2019 15:27 19.44 4.40 1 19.0 13.746 5.843 7.31 6.23 9.33 0.55 23.0 101.4 0.33 2.14 19.00 0.010 1.150 0.193 3.800 2.1 0.7

Ward Lake 2019

Appendix B. Quality Assurance/Quality Control

Table B-1. Instrument drift during the 2019 sample season. Percent Difference

Lakes Monitored Date Time DO SPC pH

Ward Lake 2019