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. Data for Beaver Creek Upground Reservoir can be found under SITE_ID NLA17_OH-10007.

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 Creek Upground Reservoir. These data will be included in a formal peer-reviewed publication to be submitted for publication in 2024.

Figure 1. Location of the 108 Reservoirs Included in Study.

2. Beaver Creek Upground Reservoir Survey Design

The Beaver Creek Upground Reservoir survey design included 15 sampling sites that were sampled on 2020-07-27. 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.

Figure 2. Location of the 15 sampling sites in Beaver Creek Upground Reservoir.

3. Lake Disturbance and Trophic Status

Lake condition 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)), 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 & <5 <3 11 least disturbed
turbidity NTU <3.7 >3.7 & <5.38 >5.38 0.43 least disturbed
TP ug/l <49 >49 & <82 >82 19 least disturbed
TN ug/l <1105 >1105 & <1699 >1699 952 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 curser over any point in the figures to reveal the siteID 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, dissolved oxygen, and temperature were relatively constant at 0.1 m depth throughout the reservoir. This likely reflects the simple shape of the reservoir and the lack of natural tributary inputs and outflows.

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, depleting dissolved oxygen to concentrations that may stress or kill oxygen sensitive organisms including some fish and insects.

The deepest sampling location in Beaver Creek Upground Reservoir was 9.1 m deep. Water temperature was relatively constant in the top 5m of the water column, but dropped to approximately 5C in the bottom 4m of the reservoir, indicating strong thermal stratification. Dissolved oxygen was abundant and homogeneous in the top of the water column, but nearly depleted near the lake bottom, indicating strong biological oxygen demand in lake sediment.

  1. Jake Beaulieu, United States Environmental Protection Agency, Office of Research and Development, ↩︎