Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY LAKEGREENHAVEN.HTML Survey of Reservoir Greenhouse gas Emissions Lake Greenhaveri Water Quality Survey Jake Beaulieu1 02 June, 2022 1. Background Between 2020 and 2023 the US Environmental Protection Agency (USEPA) will survey water quality and greenhouse gas (GHG) emissions from 108 reservoirs distributed across the United States (Figure 1). The objective of the research is to estimate the magnitude of GHG emissions from US reservoirs. All reservoirs included in this study were previously sampled by the USEPA during the 2017 National Lakes Assessment (2017 NLA). Data from the 2017 NLA can be found at the EPA website (https://www.epa.gov/national-aquatic-resource-surveys/data-national-aquatic-resource-surveys). Data for Lake Greenhaven can be found under SITEJD NLA17_CA-10003. A field sensor is used to measure chlorophyll a, dissolved oxygen, pH, specific conductivity water temperature, and turbidity near the water surface at a minimum of 15 locations within each reservoir. Water samples are collected from the deepest site for analysis of nutrients and chlorophyll a. This preliminary report presents water quality results for Lake Greenhaven. These data will be included in a formal peer-reviewed publication to be submitted for publication in 2024. Western Mountains 500 km ji; . - 300 mi (Mff!3(2/leafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, ^GP, and the GIS User Community ., GeoEye, Getmapping, Aeroflrid, IGN, I 1 of 8 7/11/2022, 7:56 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY LAKEGREENHAVEN.HTML Figure 1. Location of the 108 Reservoirs Included in Study. 2. Lake Greenhaven Survey Design The Lake Greenhaven survey design included 15 sampling sites. Water chemistry samples were collected from a 3.3m deep site (Figure 2). Click on any of the sites to see the site id, water temperature, pH, turbidity, and dissolved oxygen at the water surface. 2 of 8 7/11/2022, 7:56 AM ------- Survey of Reservoir Greenhouse gas Emissions file -JIIC :/Users/Home/Downloads/LAKESUMMARY LAKEGREENHAVEN.HTML Figure 2. Location of the 15 sampling sites in Lake Greenhaven. 3. Lake Disturbance and Trophic Status Lakes are often classified according to their trophic state. There are four trophic state categories that reflect nutrient availability and plant growth within a lake. A eutrophic lake has high nutrients and high algal and/or macrophyte plant growth. An oligotrophic lake has low nutrient concentrations and low plant growth. Mesotrophic lakes fall somewhere in between eutrophic and oligotrophic lakes and hypereutrophic lakes have very high nutrients and plant growth. Lake trophic state is typically determined by a wide variety of natural factors that control nutrient supply climate, and basin morphometry. A metric commonly used for defining trophic state is the concentration of chlorophyll a (chla), an indicator of algae abundance, in the water column. Chlorophyll a concentration was 9 ug/L during the sampling, indicating the lake was eutrophic. Trophic State Classification Analyte Oligotrophic Mesotrophic Eutrophic Hypereutrophic chlorophyll a (ug/L) <=2 >2 and <=7 >7 and <=30 >30 In addition to classifying lakes by trophic status, lakes can be classified by degree of disturbance relative to undisturbed lakes (i.e. reference lakes) within the ecoregion. Degree of disturbance can be based on a wide variety of metrics, but here we use nutrients (total phosphorus (tp), total nitrogen (tn)), suspended sediment (turbidity), chlorophyll a, and dissolved oxygen (do). Lake disturbance values range from least to most disturbed. Chemical Condition Indicators Threshold Values Observed Values parameter units least disturbed moderately disturbed most disturbed concentration status do mg/l >5 >3 & <5 <3 8 least disturbed 3 of 8 7/11/2022, 7:56 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY LAKEGREENHAVEN.HTML Threshold Values Observed Values parameter units least disturbed moderately disturbed most disturbed concentration status turbidity NTU <2.97 >2.97 t A oo >4.84 9.77 most disturbed tp ug/l <48 >48 A OO >84 317 most disturbed tn ug/l <465 >465 f * <746 >746 695 moderately disturbed chlorophyll a ug/l <6.65 >6.65 f * <12.2 >12.2 9.3 moderately disturbed 4. Within-lake Spatial Patterns A field sensor was used to measure water temperature, pH, dissolved oxygen, and turbidity near the water surface at all sampling sites. Data are reported in figures and tables below. Hover the curser over any point in the figures to reveal the sitelD corresponding to the adjacent data table. Alternatively, click on any row in the data table to reveal the location of the sampling site on the map. Turbidity was generally higher and water temperatures were slightly warmer on the north side of the lake. pH was consistent throughout the lake, likely reflecting similar rates of algal metabolism throughout the reservoir. Dissolved oxygen was generally high, with one outlier in the middle of the reservoir where the dissolved oxygen concentration was only 5.5 mg L water sitelD temp 2 25.2 3 24.6 4 24.6 5 25.9 7 24.7 8 25.1 9 25 10 23.7 11 24.9 Leaflet,(http&://leafletjs.com) les ©tsci —S= EGP, and (he GIS User'fcommunity " Aerogrii 4 of 8 7/11/2022, 7:56 AM ------- |