Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096 LAKESUMMARY LAKEOVERHOLSER.HTML Survey of Reservoir Greenhouse gas Emissions Lake Overholser 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 Overholser can be found under SITEJD NLA17_OK-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 Overholser. 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 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096 LAKESUMMARY LAKEOVERHOLSER.HTML Figure 1. Location of the 108 Reservoirs Included in Study. 2. Lake Overholser Survey Design The Lake Overholser survey design included 15 sampling sites. Water chemistry samples were collected from a 4.1, 2.7m deep site nearby the dam (Figure 2). Click on any of the sites to see the site id, water temperature, pH, turbidity, and dissolved oxygen at the water surface. -JSj + I Leaflet (https://leafletjs.com) | TiteS© Esri "UPR-EGP, and the GIS User Community 2 of 8 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096 LAKESUMMARY LAKEOVERHOLSER.HTML Figure 2. Location of the 15 sampling sites in Lake Overhoiser. 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 22 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 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096 LAKESUMMARY LAKEOVERHOLSER.HTML Threshold Values Observed Values parameter units least disturbed moderately disturbed most disturbed concentration status turbidity NTU <3.32 >3.32 I St <4.67 >4.67 475.44 most disturbed tp ug/l <34 >34 ( CD LO V >56 258 most disturbed tn ug/l <657 >657 f X" A OO U> O >830 829 moderately disturbed chlorophyll a ug/l <6.85 >6.85 f xw A CO oo >13.8 22.1 most 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 is highest near the river inflows, but decreases toward the dam as suspended sediment drops out of the water column, although turbidity is likely driven by wind mixing in this system. Water temperature is lowest near the river inflows and reflects warming of water through solar heating as it moves through the reservoir. Dissolved oxygen and pH are greatest at sampling sites where temperature is highest and turbidity is lowest, likely reflecting high rates of algal metabolism in the relatively warm and clear water. water sitelD temp 1 30.38 2 29.74 3 29.82 4 31.75 5 29.78 6 28.5 7 28.34 8 32.73 Leaflet (https://leafletjs com) | Tiles^ Ei EGP, and the GIS User Community 4 of 8 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096_LAKESUMMARY_LAKEOVERHOLSER.HTML 500 m water 2000 ft sitelD temp 9 29.87 10 29.85 11 30.62 12 29.08 13 31.89 14 30.25 sitelD pH 47 1 9.38 2 9.36 3 9.35 4 9.42 5 9.32 6 9.35 7 9.34 8 9.47 9 9.3 10 9.37 11 9.3 12 9.23 13 9.37 14 9.34 15 9.46 itps://leafletjs.com) | I iles © Esri — Sourcte: the GiS User Qommunity 5 of 8 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096 LAKESUMMARY LAKEOVERHOLSER.HTML sitelD Turbidity (NTU) 1 2 3 4 5 7 8 9 10 11 12 13 14 15 14.8 14.6 14.8 16 15.8 16.4 16.3 17.2 15 17.4 23.4 15.2 14.5 16.4 DO sitelD (mg/L) 1 11.02 2 10.3 3 14 4 4.86 5 119 6 of 8 6/27/2022. 1:52 PM .eaflet (https://leafletjs.com) | Tiles ©*r - Sour EGP, and the GIS User Community lapping ------- Wt PjMv' $ L 1 25! Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096_LAKESUMMARY_LAKEOVERHOLSER.HTML DO _ sitelD (mg/L) Oxygen 1 a ' (mg/L) - 5 - 6 - 7 - 8 - 9 -10 5. Depth Profiles 6 9.15 7 9.51 8 14.34 9 12.72 10 14.44 11 12.69 12 8.5 13 13.35 14 14.37 15 13.52 Dissolved oxygen is one of the most important environmental factors affecting aquatic life. The biological demand for oxygen is often greatest near the sediment where the decomposition of organic matter consumes oxygen through aerobic respiration. Near the surface of lakes, photosynthesis by phytoplankton produces oxygen, often leading to a general pattern of decreasing oxygen availability with increasing depth. This pattern can be exacerbated by thermal stratification. Thermal stratification occurs when lake surface waters are warmed by the sun, causing the water to become less dense and float on top of the deeper, cooler lake water. Since the deeper layer of water cannot exchange gases with the atmosphere, the dissolved oxygen content of the deep water cannot be replenished from the atmosphere. As a result, the deep water can become progressively depleted of oxygen as it is consumed by biological activity, sometimes causing dissolved oxygen to become sufficiently scarce to stress oxygen sensitive organisms including some fish and insects. The deepest sampling location in Lake Overholser was 4.1, 2.7 m deep. In relatively shallow lakes like Lake Overholser, wind induced mixing of the water column is often sufficient to prevent thermal stratification. Lake Overholser had only minor thermal stratification, yet dissolved oxygen was nearly depleted near the lake bottom, indicating strong biological oxygen demand in lake sediment. 7 of 8 6/27/2022, 1:52 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/600S22096_LAKESUMMARY_LAKEOVERHOLSER.HTML Lake Overholser Depth Profiles Temperature (°C) 10 15 20 25 30 Dissolved Oxygen (mg L 1) 1. Jake Beaulieu, United States Environmental Protection Agency, Office of Research and Development, Beaulieu.Jake@epa.gov (mailto:Beaulieu.Jake@epa.gov)«J 8 of 8 6/27/2022, 1:52 PM ------- |