Windy Gap Reservoir
Grand County, Colorado108 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from B at the last regrade
- Mesotrophic
- #7 of 7 in the county
- 15 ft max depth
Windy Gap Reservoir in Grand County, Colorado has a water quality grade of D (Nutrient-rich). Phosphorus: 52 µg/L. Chlorophyll-a (algae): 3 µg/L. Surface area: 108 acres.
- Max depth
- ~15 ft est.
- Area
- 108 acres
- Type
- Mesotrophic
- Trend
- → Stable
Stays via Stay22
Stays near Windy Gap Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Windy Gap Reservoir in Grand 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 Windy Gap Reservoir are listed below.
Top-rated places to stay near Windy Gap Reservoir
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Watch Windy Gap Reservoir’s letter
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Windy Gap Reservoir is a 108-acre mesotrophic lake in Grand County, Colorado with an estimated average depth of about 15 feet. Water quality is graded D based on 2 sampling years through 2023. Phosphorus level is improving over recent sampling years. Compared to the 6 other monitored lakes in Grand County, Windy Gap Reservoir ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2023-07-10. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyElevated nutrients
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)
No clarity data. Phosphorus 52 µg/L. Chlorophyll-a 3 µg/L. TSI 51. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 52 µg/L | Poor |
| Chlorophyll-a (Algae) | 3 µg/L | Fair |
| Trophic State Index (TSI) | 51 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~15 ft est. |
| Average Depth | ~12 ft est. |
| Surface Area | 108 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 Windy Gap 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.
Fishing Windy Gap Reservoir
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -19.75 µg/L/yr | 3 |
| Chlorophyll-a | ↓ Declining | +0.7 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Windy Gap Reservoir is a man-made reservoir impounded by the Windy Gap (completed 1985), built primarily for irrigation on the Colorado River; earth-type dam, 43 ft tall and 4,955 ft long.
- Surface area
- 108 ac
- Normal storage
- 445 ac-ft
- Max storage
- 1,633 ac-ft
- Drainage area
- 773 sq mi
- Hazard class
- Significant
- Owner
- NORTHERN COLORADO WATER CONSERVANCY DISTRICT (FRIA
All listed purposes: Irrigation;Water Supply.
Source: USACE National Inventory of Dams, NID ID CO02593 · Operator website
County Ranking
Ranked #7 of 7 lakes in Grand County
Nearby Lakes With Higher Grades
Windy Gap Reservoir holds Grade D. 2 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Grand County
Frequently asked questions about Windy Gap Reservoir
Where is Windy Gap Reservoir?
- Windy Gap Reservoir is a lake in Grand County, Colorado. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Windy Gap Reservoir?
- Windy Gap Reservoir in Grand County, Colorado has a water quality grade of D (Nutrient-rich). Phosphorus: 52 µg/L. Chlorophyll-a (algae): 3 µg/L. Surface area: 108 acres.
Is Windy Gap Reservoir safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Windy Gap Reservoir?
- No published bathymetric survey covers Windy Gap Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 15 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 108 acres.
Explore Windy Gap Reservoir across LakeQuality
7.3 mi away · recorded at 111°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
Colorado's cleanest and most-polluted lakes, ranked
Planning a trip around Rocky Mountain?
Windy Gap Reservoir is about 23 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 Colorado Lake Rankings
Other Grade D Lakes in Colorado
Mesotrophic Lakes in Colorado
Where this data comes from
266 measurements from 1 monitoring station, 2021–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Colorado Water Science Center
USGS-CO266 samples · 2021–2023
Analytical methods
- 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)
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)