Mountain Run Lake
Culpeper County, Virginia75 acresView mapDirections
Virginia DEQ publishes the water-quality measurements for Mountain Run Lake. Here is what has been measured.
- Eutrophic
- Impaired · Pathogens (E. coli, fecal)
- 37 ft max depth
- Public access
Mountain Run Lake in Culpeper County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 2.6 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 17.3 µg/L. Surface area: 75 acres.
Mountain Run Lake is a 75-acre productive, nutrient-rich eutrophic lake in Culpeper County, Virginia with an estimated average depth of about 37 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Culpeper County, Mountain Run Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Virginia DEQ, last sampled 2022-10-06. Methodology: how these readings are compared.
What Mountain Run Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyBacteria advisory
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. Mountain Run Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pathogens (E. coli, fecal). Check local advisories before you swim.
Whether Mountain Run Lake 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 Mountain Run Lake
These are the measurements Virginia DEQ publishes for Mountain Run Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Very murky, less than 2.6 ft of visibility. Phosphorus 40 µg/L. Chlorophyll-a 17.3 µg/L. TSI 60.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 2.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 40µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 17.3µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 60 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Mountain Run Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~37 ft est.
Surface area
75 acres
Public access
Yes
Listed by Virginia DEQ
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Virginia has not published bathymetry for Mountain Run Lake.
Lake Size & Watershed
Watershed (drainage) area
6 sq mi
HydroLAKES / HydroSHEDS
Shoreline
2.2 mi
HydroLAKES / HydroSHEDS
Elevation
440 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Mountain Run LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Mountain Run Lake
Compare lakeside cabins, hotels, and vacation rentals near Mountain Run Lake in Culpeper County, Virginia — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Mountain Run Lake are listed below.
Top-rated places to stay near Mountain Run Lake
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Virginia’s top lakes →
Follow Mountain Run Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Mountain Run Lake
Water Quality Trend: Worsening
Based on 4 years of monitoring (2014–2022).
Water clarity
Worsening4 years
Phosphorus
Worsening+1.1 µg/L/yr4 years
Chlorophyll-a
Worsening+1.11 µg/L/yr4 years
Reservoir Info (USACE NID)
Mountain Run Lake is a man-made reservoir impounded by the Mountain Run Dam #11, built primarily for flood risk reduction on the Mountain Run; earth-type dam, 44 ft tall and 722 ft long.
- Surface area
- 75 ac
- Normal storage
- 611 ac-ft
- Max storage
- 2,880 ac-ft
- Drainage area
- 6.46 sq mi
- Hazard class
- High
- Owner
- Town of Culpeper
All listed purposes: Flood Risk Reduction;Water Supply.
Source: USACE National Inventory of Dams, NID ID VA047002 · Operator website
EPA Impairment Status
Mountain Run Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit VAN-E09L_MTN02A02 · Official waterbody report
Nearby Lakes in Culpeper County
Frequently asked questions about Mountain Run Lake
Where is Mountain Run Lake?
- Mountain Run Lake is a lake in Culpeper County, Virginia. Its water-quality measurements are published by Virginia DEQ and shown on this page as reported.
What is the water quality of Mountain Run Lake?
- Mountain Run Lake in Culpeper County, Virginia has water-quality measurements published by Virginia DEQ, shown here as reported. Water clarity: 2.6 ft visibility. Phosphorus: 40 µg/L. Chlorophyll-a (algae): 17.3 µg/L. Surface area: 75 acres.
Is Mountain Run Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Mountain Run Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for pathogens (E. coli, fecal). Check local advisories before you swim.
How deep is Mountain Run Lake?
- No published bathymetric survey covers Mountain Run Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 37 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 75 acres.
Are there boat ramps on Mountain Run Lake?
- Mountain Run Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Mountain Run Lake. Public access is listed as yes.
Can I fish at Mountain Run Lake?
- Mountain Run Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Virginia's fish and wildlife agency, so check its current regulations before you go.
Explore Mountain Run Lake across LakeQuality
2 documented falls within 20.5 mi, nearest Dark Hollow Falls
Species activity outlook by water temperature and season
Where to stay at Virginia's top lakes, each with its readings
Virginia's cleanest lakes, ranked on agency measurements
Planning a trip around Shenandoah?
Mountain Run Lake is about 22 miles from Shenandoah National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Shenandoah →More lakes in Virginia
Other Lakes in Virginia
Eutrophic Lakes in Virginia
Where this data comes from
207 measurements from 2 monitoring stations, 2014–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- VIRGINIA DEPARTMENT OF ENVIRONMENTAL QUALITY
21VASWCB207 samples · 2014–2022
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
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory