Coles Run Reservoir
Augusta County, Virginia5 acresView mapDirections
Virginia DEQ publishes the water-quality measurements for Coles Run Reservoir. Here is what has been measured.
- Oligotrophic
- Impaired · pH / acidity
Coles Run Reservoir in Augusta County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 25.8 ft visibility. Phosphorus: 5 µg/L. Chlorophyll-a (algae): 0.5 µg/L. Surface area: 5 acres.
Coles Run Reservoir is a 5-acre cold, clear oligotrophic lake in Augusta County, Virginia. Overall water quality is declining over recent sampling years. Compared to the 2 other monitored lakes in Augusta County, Coles Run Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Virginia DEQ, last sampled 2024-10-03. Methodology: how these readings are compared.
What Coles Run Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water25.8 ft of visibility
Swimming conditions
Readings onlyLow algae
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Coles Run Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for pH / acidity. Check local advisories before you swim.
Whether Coles Run Reservoir is safe to swim in today is a call for the Virginia Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Coles Run Reservoir
These are the measurements Virginia DEQ publishes for Coles Run Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Crystal clear, you can see 25.8 ft down. Phosphorus 5 µg/L. Chlorophyll-a 0.5 µg/L. TSI 27.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 25.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 5µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 0.5µg/L | Good GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 27 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Coles Run Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
5 acres
No bathymetric survey has been published for Coles Run Reservoir, so its depth is not documented here.
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Fishing Coles Run Reservoir
Water Quality Trend: Worsening
Based on 4 years of monitoring (2017–2024).
Water clarity
Stable4 years
Phosphorus
Worsening+0.16 µg/L/yr4 years
Chlorophyll-a
Stable0 µg/L/yr4 years
Reservoir Info (USACE NID)
Coles Run Reservoir is a man-made reservoir impounded by the Coles Run Dam, built primarily for water supply on the Coles Run; earth-type dam, 65 ft tall and 540 ft long.
- Surface area
- 5 ac
- Normal storage
- 181 ac-ft
- Max storage
- 256 ac-ft
- Drainage area
- 2.56 sq mi
- Hazard class
- High
- Owner
- Augusta County Service Authority
Source: USACE National Inventory of Dams, NID ID VA015019 · Operator website · Matched by proximity (0.06 km)
EPA Impairment Status
Coles Run Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Aquatic life.
Source: EPA ATTAINS assessment unit VAV-B31L_00 · Official waterbody report
Nearby Lakes in Augusta County
Frequently asked questions about Coles Run Reservoir
Where is Coles Run Reservoir?
- Coles Run Reservoir is a lake in Augusta County, Virginia. Its water-quality measurements are published by Virginia DEQ and shown on this page as reported.
What is the water quality of Coles Run Reservoir?
- Coles Run Reservoir in Augusta County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 25.8 ft visibility. Phosphorus: 5 µg/L. Chlorophyll-a (algae): 0.5 µg/L. Surface area: 5 acres.
Is Coles Run Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Coles Run Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for pH / acidity. Check local advisories before you swim.
Explore Coles Run Reservoir across LakeQuality
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Where this data comes from
119 measurements from 1 monitoring station, 2017–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- VIRGINIA DEPARTMENT OF ENVIRONMENTAL QUALITY
21VASWCB119 samples · 2017–2024
Analytical methods
- Tyler, John. 1968. The secchi disk, Limnology and Oceanograpy, 13(1):1-6.
- Total Phosphorus After Block Digestion
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 2130 B ~ Nephelometric Method
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database