Douglas Reservoir
Larimer County, Colorado565 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from D at the last regrade
- Mesotrophic
- #3 of 9 in the county
- 16 ft max depth
- Public access
- Limited data
Douglas Reservoir in Larimer County, Colorado has a water quality grade of A (Excellent). Water clarity: 4.1 ft visibility. Phosphorus: 11 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Surface area: 565 acres.
- Clarity
- 4.1 ft
- Max depth
- ~16 ft est.
- Area
- 565 acres
- Type
- Mesotrophic
- Public access
- Yes
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Watch Douglas Reservoir’s letter
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Douglas Reservoir is a 565-acre mesotrophic lake in Larimer County, Colorado with an estimated average depth of about 16 feet. Water quality is graded A based on 3 sampling years through 2021. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 8 other monitored lakes in Larimer County, Douglas Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2021-09-08. Grade methodology: LakeQuality methodology.
What Douglas Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
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 A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Murky, only visible to about 4.1 ft. Phosphorus 11 µg/L. Chlorophyll-a 2.5 µg/L. TSI 45. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.1 ft | Not graded |
| Phosphorus | 11 µg/L | Good |
| Chlorophyll-a (Algae) | 2.5 µg/L | Good |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~16 ft est. |
| Surface Area | 565 acres |
| 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 Douglas 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
- Douglas Reservoir State Wildlife AreaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Douglas Reservoir
Reservoir Info (USACE NID)
Douglas Reservoir is a man-made reservoir impounded by the Douglas (completed 1901), built primarily for irrigation on the Dry Creek; earth-type dam, 47 ft tall and 3,700 ft long.
- Surface area
- 565 ac
- Normal storage
- 8,940 ac-ft
- Max storage
- 13,324 ac-ft
- Drainage area
- 43 sq mi
- Hazard class
- High
- Owner
- WRCC, INC. (NELSON, KIMBERLY)
All listed purposes: Irrigation;Fish and Wildlife Pond.
Source: USACE National Inventory of Dams, NID ID CO01163 · Operator website
County Ranking
Ranked #3 of 9 lakes in Larimer County
Nearby Lakes in Larimer County
Frequently asked questions about Douglas Reservoir
Where is Douglas Reservoir?
- Douglas Reservoir is a lake in Larimer County, Colorado. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Douglas Reservoir?
- Douglas Reservoir in Larimer County, Colorado has a water quality grade of A (Excellent). Water clarity: 4.1 ft visibility. Phosphorus: 11 µg/L. Chlorophyll-a (algae): 2.5 µg/L. Surface area: 565 acres.
Is Douglas Reservoir safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Douglas Reservoir?
- No published bathymetric survey covers Douglas Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 16 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 565 acres.
Are there boat ramps on Douglas Reservoir?
- Douglas Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Douglas Reservoir State Wildlife Area. Public access is listed as yes.
Explore Douglas Reservoir across LakeQuality
More Colorado Lake Rankings
Other Grade A 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