Coles Run Reservoir
Augusta County, Virginia5 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · pH / acidity
- #3 of 3 in the county
Coles Run Reservoir in Augusta County, Virginia has a water quality grade of A (Excellent). Water clarity: 25.8 ft visibility. Phosphorus: 5 µg/L. Chlorophyll-a (algae): 0.5 µg/L. Surface area: 5 acres.
- Clarity
- 25.8 ft
- Area
- 5 acres
- Type
- Oligotrophic
- Phosphorus
- 5 µg/L
- Chlorophyll-a
- 0.5 µg/L
- Trend
- ↓ Declining
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Watch Coles Run Reservoir’s letter
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Coles Run Reservoir is a 5-acre cold, clear oligotrophic lake in Augusta County, Virginia. Water quality is graded A based on 2 sampling years through 2024. 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. Grade methodology: LakeQuality methodology.
What Coles Run Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water25.8 ft of visibility
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, 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.
Water Quality Grade: A (Excellent)
Crystal clear, you can see 25.8 ft down. Phosphorus 5 µg/L. Chlorophyll-a 0.5 µg/L. TSI 27. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 25.8 ft | Not graded |
| Phosphorus | 5 µg/L | Good |
| Chlorophyll-a (Algae) | 0.5 µg/L | Good |
| Trophic State Index (TSI) | 27 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 5 acres |
No bathymetric survey has been published for Coles Run Reservoir, so its depth is not documented here.
Fishing Coles Run Reservoir
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.08 m/yr | 4 |
| Phosphorus | ↓ Declining | +0.16 µg/L/yr | 4 |
| Chlorophyll-a | → Stable | 0 µg/L/yr | 4 |
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
Source: EPA ATTAINS assessment unit VAV-B31L_00 · Official waterbody report · Matched by proximity (0.14 km)
County Ranking
Ranked #3 of 3 lakes in Augusta County
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. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Coles Run Reservoir?
- Coles Run Reservoir in Augusta County, Virginia has a water quality grade of A (Excellent). 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?
- The A is nutrients and algae, 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
9 mi away · 1,000 ft
Species activity outlook by water temperature and season
Where to stay at Virginia's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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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)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database