Willow Creek Reservoir
Grand County, Colorado303 acresView mapDirections
Colorado WQCD publishes the water-quality measurements for Willow Creek Reservoir. Here is what has been measured.
- Mesotrophic
- Impaired · Metals (other than mercury)
- 20 ft max depth
Willow Creek Reservoir in Grand County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 75.5 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 303 acres.
Willow Creek Reservoir is a 303-acre mesotrophic lake in Grand County, Colorado with an estimated average depth of about 20 feet. Overall water quality is improving over recent sampling years. Compared to the 6 other monitored lakes in Grand County, Willow Creek Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2024-01-29. Methodology: how these readings are compared.
What Willow Creek Reservoir is good for
From access and monitoring records, not editorial picks.
- Camping2 public campgrounds nearby
Swimming conditions
Readings onlyModerate 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. Willow Creek Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury). Check local advisories before you swim.
Whether Willow Creek Reservoir is safe to swim in today is a call for the Water Quality Control Division of the Colorado Department of Public Health and Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Willow Creek Reservoir
These are the measurements Colorado WQCD publishes for Willow Creek Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.9 ft. Phosphorus 75.5 µg/L. Chlorophyll-a 2.4 µg/L. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 75.5µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 2.4µg/L | Fair GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 54 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Willow Creek Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~20 ft est.
Surface area
303 acres
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for Willow Creek Reservoir.
Lake Size & Watershed
Watershed (drainage) area
136 sq mi
HydroLAKES / HydroSHEDS
Shoreline
5.4 mi
HydroLAKES / HydroSHEDS
Elevation
8,140 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
Public campgrounds near Willow Creek Reservoir
- Willow Creek Group1.0 kmReserve
- Willow Creek1.1 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
Stays via Stay22
Stays near Willow Creek Reservoir
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Top-rated places to stay near Willow Creek Reservoir
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Fishing Willow Creek Reservoir
Water quality readings over time
3 seasons of samples on record (2021–2023). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving3 years
Phosphorus
Worsening+5.5 µg/L/yr3 years
Chlorophyll-a
Improving-1 µg/L/yr2 years
Reservoir Info (USACE NID)
Willow Creek Reservoir is a man-made reservoir impounded by the Willow Creek Bor CO Dam (completed 1953), built primarily for irrigation on the Willow Creek; earth-type dam, 127 ft tall and 1,100 ft long.
- Surface area
- 303 ac
- Normal storage
- 10,553 ac-ft
- Max storage
- 11,177 ac-ft
- Drainage area
- 127 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Irrigation;Recreation.
Source: USACE National Inventory of Dams, NID ID CO01670 · Operator website · Matched by proximity (0.16 km)
EPA Impairment Status
Willow Creek Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit COUCUC12_D · Official waterbody report
Nearby Lakes in Grand County
Frequently asked questions about Willow Creek Reservoir
Where is Willow Creek Reservoir?
- Willow Creek Reservoir is a lake in Grand County, Colorado. Its water-quality measurements are published by Colorado WQCD and shown on this page as reported.
What is the water quality of Willow Creek Reservoir?
- Willow Creek Reservoir in Grand County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 75.5 µg/L. Chlorophyll-a (algae): 2.4 µg/L. Surface area: 303 acres.
Is Willow Creek Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Willow Creek Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury). Check local advisories before you swim.
How deep is Willow Creek Reservoir?
- No published bathymetric survey covers Willow Creek Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 20 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 303 acres.
Are there campgrounds on Willow Creek Reservoir?
- Willow Creek Reservoir has 2 public campgrounds from USGS The National Map within 5 km, including Willow Creek Group, Willow Creek. 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 Willow Creek Reservoir across LakeQuality
Planning a trip around Rocky Mountain?
Willow Creek Reservoir is about 19 miles from Rocky Mountain 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 Rocky Mountain →More lakes in Colorado
Other Lakes in Colorado
Mesotrophic Lakes in Colorado
Where this data comes from
1,280 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Colorado Water Science Center
USGS-CO1,280 samples · 2020–2024
Analytical methods
- Secchi disk method
- Phosphorus, LL,wu,persulfate(CO)
- YSI EXO, 470/685/40,S bacillaris
- Plant pigments, sonication & 445
- YSI EXO turbidity sensor, FNU
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Public campgrounds from USGS The National Map Structures, within about 3 miles