Elevenmile Reservoir
Park County, ColoradoView mapDirections
Nutrients and algae run above the regional average.
↓ down from B at the last regrade
- Mesotrophic
- #2 of 2 in the county
- 112 ft max depth
- Public access
- Limited data
Elevenmile Reservoir in Park County, Colorado has a water quality grade of D (Nutrient-rich). Water clarity: 13.1 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
- Clarity
- 13.1 ft
- Max depth
- ~112 ft est.
- Type
- Mesotrophic
- Public access
- Yes
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Stays near Elevenmile Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Elevenmile Reservoir in Park County, Colorado — 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 grade measures nutrients and algae, not lodging — cabins and rentals around Elevenmile Reservoir are listed below.
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Elevenmile Reservoir is a mesotrophic lake in Park County, Colorado with an estimated average depth of about 112 feet. Water quality is graded D based on 3 sampling years through 2021. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 1 other monitored lakes in Park County, Elevenmile Reservoir ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2021-09-23. Grade methodology: LakeQuality methodology.
What Elevenmile Reservoir is good for
From access and monitoring records, not editorial picks.
- Clear water13.1 ft of visibility
- Boat launch3 documented ramps
- Camping2 public campgrounds nearby
Swimming Safety
Grade onlyLimited data
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 D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Good clarity, visible to about 13.1 ft. Phosphorus 33 µg/L. Chlorophyll-a 5.5 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.1 ft | Not graded |
| Phosphorus | 33 µg/L | Fair |
| Chlorophyll-a (Algae) | 5.5 µg/L | Poor |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~112 ft est. |
| Average Depth | ~42 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for Elevenmile Reservoir.
Lake Size & Watershed
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
- Eleven Mile State ParkPublic
- Eleven Mile State ParkPublic
- Eleven Mile State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Elevenmile Reservoir
- Spillway4.7 km
- Cove4.9 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Elevenmile Reservoir
County Ranking
Ranked #2 of 2 lakes in Park County
Nearby Lakes in Park County
Frequently asked questions about Elevenmile Reservoir
Where is Elevenmile Reservoir?
- Elevenmile Reservoir is a lake in Park County, Colorado. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Elevenmile Reservoir?
- Elevenmile Reservoir in Park County, Colorado has a water quality grade of D (Nutrient-rich). Water clarity: 13.1 ft visibility. Phosphorus: 33 µg/L. Chlorophyll-a (algae): 5.5 µg/L.
Is Elevenmile Reservoir safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Elevenmile Reservoir?
- No published bathymetric survey covers Elevenmile Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 112 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Elevenmile Reservoir?
- Elevenmile Reservoir has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Eleven Mile State Park, Eleven Mile State Park, Eleven Mile State Park. Public access is listed as yes.
Are there campgrounds on Elevenmile Reservoir?
- Elevenmile Reservoir has 2 public campgrounds from USGS The National Map within 5 km, including Spillway, Cove. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Elevenmile Reservoir across LakeQuality
16.3 mi away · recorded at 126°F
Species activity outlook by water temperature and season
Where to stay at Colorado's top lakes, each with its grade
Moderate nutrients, good water quality
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Other Grade D Lakes in Colorado
Mesotrophic Lakes in Colorado
Where this data comes from
16 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX16 samples · 2021
Analytical methods
- Secchi disk depth measurement
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrogen in Water by Pyrolysis Detection
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles