Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML Survey of Reservoir Greenhouse gas Emissions Beaver Pond 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 Beaver Pond can be found under SITEJD NLA17_VA-10001. 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 Beaver Pond. 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, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML Figure 1. Location of the 108 Reservoirs Included in Study. 2. Beaver Pond Survey Design The Beaver Pond survey design included 15 sampling sites. Water chemistry samples were collected from a 2.9m deep site on the east end of the lake (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, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file :///C :/Users/Home/Downloads/LAKE SUMMARY BEAVERPOND.HTML Figure 2. Location of the 15 sampling sites in Beaver Pond. 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 18 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 moderately 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 4 moderately disturbed 3 of 8 7/11/2022, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML Threshold Values Observed Values parameter units least disturbed moderately disturbed most disturbed concentration status turbidity NTU <2.83 >2.83 t * <3.94 >3.94 29.68 most disturbed tp ug/l <19 >19 I A CO CO >33 34 most disturbed tn ug/l <309 >309 f * <407 >407 435 most disturbed chlorophyll a ug/l <5.23 CO Csl LO A x <11.5 >11.5 17.9 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 typically highest near the river inflows, but decreases toward the dam as water velocity decreases and suspended sediment drops out of the water column. This pattern was not observed at Beaver Pond, perhaps due to its small size. The spatial pattern of water temperature reflects the time of sampling, with cooler temperatures reflective of samples collected in the morning and warmer temperatures reflective of afternoon sampling. Surface dissolved oxygen concentrations tended to be higher on the west end of the lake while the opposite pattern was observed for pH. water sitelD temp 1 28.9 2 29.7 3 30.3 4 30.9 5 28.8 6 29.8 9 28.4 10 29.7 Leaflet (https://leafletjs.ci EGP, and the G?s'u?er| 4 of 8 7/11/2022, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions Leaflet (https://leafletjs.cptr'') I Tiles'1 EGP, and the GIS User&ommunity 5 of 8 file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML water sitelD temp 11 30.3 12 30.9 13 29.2 14 30 15 30.4 sitelD pH 1 7.69 2 7.37 3 6.82 4 6.6 5 7.55 6 7.5 9 7.67 10 7.36 11 6.82 12 7.2 13 7.62 14 7.31 15 6.9 7/11/2022, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML Leaflet (https://leafletjs. EGP, and the GIS User ipping, Aerogrid, IGN, IGP, UPR- immunity sitelD Turbidity (NTU) 1 7.6 2 7.4 3 9.7 4 8.4 5 8.6 6 6.1 9 10.8 10 8.1 11 8.8 12 7.3 13 7.4 14 6.7 15 8 DO sitelD (mg/L) 1 7.41 2 9.14 3 8.5 4 9.7 ;ommi 6 of 8 7/11/2022, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file:///C:/Users/Home/Downloads/LAKESUMMARY BEAVERPOND.HTML Dissolved fftcygen fthg/L) » DO sitelD (mg/L) 5 7,4 6 10.1 9 5.36 10 9.25 11 8.4 12 9.3 13 8.31 14 9.5 15 10 5. Depth Profiles 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 Beaver Pond was 2.9 m deep. In relatively shallow lakes like Beaver Pond, wind induced mixing of the water column is often sufficient to prevent thermal stratification. Beaver Pond was not thermally stratified, yet dissolved oxygen was nearly depleted near the lake bottom, indicating strong biological oxygen demand in lake sediment. 7 of 8 7/11/2022, 7:57 AM ------- Survey of Reservoir Greenhouse gas Emissions file :///C :/Users/Home/Downloads/LAKE SUMMARY BEAVERPOND.HTML Beaver Pond 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 7/11/2022, 7:57 AM ------- |