Survey of Reservoir Greenhouse gas Emissions file:///P:/PDF_Harvest/ScienceInventory/ScienceInventoiyHarvest/600. Survey of Reservoir Greenhouse gas Emissions Rosser Park Lake Water Quality Survey Jake Beaulieu 25 July, 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 Rosser Park Lake can be found under SITE J D NLA17JN-10141. Afield sensor is used to measure chlorophyll a, dissolved oxygen, pH, specific conductivity, water temperature, and turbidity near the water surface at 10-20 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 Rosser Park Lake. These data will be included in a formal peer-reviewed publication to be submitted for publication in 2024. Ecoregions Coastal Plains Northern Appalachians Northern Plains Southern Appalachians Southern Plains I ¦ - u. .fx Temperate Plains Upper Midwest Western Mountains Leaflet (https://leafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGR UPR-EGP, and the GIS User Community Figure 1, Location of the 108 Reservoirs Included in Study. 2. Rosser Park Lake Survey Design The Rosser Park Lake survey design included 12 sampling sites that were sampled on 2020-08-26. Water chemistry samples were collected from a 9.1m 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. Sample sites sensor sites Leaflet (https://leafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community _ _ ¦ 1 of 5 12/14/2022. 1:37 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///P:/PDF_Harvest/ScienceInventory/ScienceInventoryHarvest/600... Figure 2. Location of the 15 sampling sites in Rosser Park Lake. 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, an indicator of algae abundance, in the water column. Chlorophyll a concentration was 5 ug/L during the sampling, indicating the lake was mesotrophic. 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). All lake disturbance values are least disturbed. Chemical Condition Indicators Measured at Water Chemistry Site Threshold Values Observed Values parameter units least disturbed moderately disturbed most disturbed concentration status do mg/l >5 >3. 3c <5 <3 7 least disturbed turbidity NTU <3.7 >3.7 8 OO CO LO V >5.38 0.97 least disturbed tp ug/l <49 V CO CM OO V >82 18 least disturbed tn ug/l <1105 LD O A i <1699 >1699 532 least disturbed chlorophyll a ug/l <13.9 >13.9 < i <22.7 >22.7 5.4 least 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 cursor over any point in the figures 2 of 5 12/14/2022. 1:37 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///P:/PDF_Harvest/ScienceInventory/ScienceInventoiyHarvest/600. 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. Water temperature, pH, turbidity, and dissolved oxygen were fairly uniform through the surface waters with no evidence of strong spatial patterning. water sitelD temp 3 28.43 4 28.65 5 28.25 6 28.68 7 28.51 10 29.16 11 28.44 12 28.51 13 28.06 14 28.5 15 28.97 sitelD pH 3 8.91 4 8.88 5 8.86 6 8.7 7 8.81 10 8.84 11 8.86 12 8.85 13 8.79 14 8.81 15 8.83 Turbidity sitelD (NTU) 2.5 2.4 1.5 Water Temp. (Leaflet (https://leafietjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, GetmajDping, Aerogrid, IGN, IGP, UPR^EGP, jand the GIS User Community (Leaflet (https://leafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, GetmajDping, Aerogrid, IGN, IGP, UPRJEGP,_and the GIS User Community . ¦:' ¦ ' (https://ieafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community 3 of 5 12/14/2022. 1:37 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///P:/PDF_Harvest/ScienceInventory/ScienceInventoiyHarvest/600... Turbidity sitelD (NTU) DO sitelD (mg/L) 3 7.09 4 8.25 5 8.19 6 8.16 7 7.9 10 8.05 11 7.91 12 7.91 13 7.85 14 7.94 15 8 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. Rosser Park Lake had strong thermal stratification at the 9.1 m deep water chemistry sampling site. Dissolved oxygen was nearly depleted near the lake bottom, indicating strong biological oxygen demand in lake sediment. Dissolved Oxygen fmg/L) [Leaflet (https://leafletjs.com) | Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid IGN, IGP, UPR^EGP, arid the GIS User Community 4 of 5 12/14/2022. 1:37 PM ------- Survey of Reservoir Greenhouse gas Emissions file:///P:/PDF_Harvest/ScienceInventory/ScienceInventoryHarvest/600. Rosser Park Lake 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 5 of 5 12/14/2022, 1:37 PM ------- |