Shadow Mountain Lake
Grand County, Colorado1,852 acresView mapDirections
Nutrients and algae run above the regional average.
↓ down from B at the last regrade
- Mesotrophic
- #6 of 7 in the county
- 39 ft max depth
Shadow Mountain Lake in Grand County, Colorado has a water quality grade of D (Nutrient-rich). Water clarity: 7.9 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 5.1 µg/L. Surface area: 1852 acres.
- Clarity
- 7.9 ft
- Max depth
- ~39 ft est.
- Area
- 1,852 acres
- Type
- Mesotrophic
- Trend
- → Stable
Stays via Stay22
Stays near Shadow Mountain Lake
Compare lakeside cabins, hotels, and vacation rentals near Shadow Mountain Lake 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 Shadow Mountain Lake are listed below.
Top-rated places to stay near Shadow Mountain Lake
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Watch Shadow Mountain Lake’s letter
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Shadow Mountain Lake is a 1,852-acre mesotrophic lake in Grand County, Colorado with an estimated average depth of about 39 feet. Water quality is graded D based on 2 sampling years through 2024. Water clarity is declining over recent sampling years. Compared to the 6 other monitored lakes in Grand County, Shadow Mountain Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2024-01-30. Grade methodology: LakeQuality methodology.
What Shadow Mountain Lake is good for
From access and monitoring records, not editorial picks.
- Camping2 public campgrounds nearby
- Big water1,852 acres
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. Shadow Mountain Lake is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury). Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Moderate clarity, visible to about 7.9 ft. Phosphorus 20 µg/L. Chlorophyll-a 5.1 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.9 ft | Not graded |
| Phosphorus | 20 µg/L | Good |
| Chlorophyll-a (Algae) | 5.1 µg/L | Poor |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~39 ft est. |
| Average Depth | ~15 ft est. |
| Surface Area | 1,852 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 Shadow Mountain Lake.
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
Public campgrounds near Shadow Mountain Lake
- Green Ridge1.3 km
- Cutthroat Bay4.0 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 Shadow Mountain Lake
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -5.5 m/yr | 3 |
| Phosphorus | → Stable | 0 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -1 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Shadow Mountain Lake is a man-made reservoir impounded by the Shadow Mountain Dam (completed 1946), built primarily for irrigation on the Colorado River; earth-type dam, 63 ft tall and 3,077 ft long.
- Surface area
- 1,852 ac
- Normal storage
- 18,369 ac-ft
- Max storage
- 18,369 ac-ft
- Drainage area
- 184.47 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
Source: USACE National Inventory of Dams, NID ID CO01666 · Operator website
EPA Impairment Status
Shadow Mountain Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit COUCUC12_B · Official waterbody report
County Ranking
Ranked #6 of 7 lakes in Grand County
Nearby Lakes With Higher Grades
Shadow Mountain Lake 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 Shadow Mountain Lake
Where is Shadow Mountain Lake?
- Shadow Mountain Lake 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 Shadow Mountain Lake?
- Shadow Mountain Lake in Grand County, Colorado has a water quality grade of D (Nutrient-rich). Water clarity: 7.9 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 5.1 µg/L. Surface area: 1852 acres.
Is Shadow Mountain Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Shadow Mountain Lake 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 Shadow Mountain Lake?
- No published bathymetric survey covers Shadow Mountain Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 39 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 1852 acres.
Are there campgrounds on Shadow Mountain Lake?
- Shadow Mountain Lake has 2 public campgrounds from USGS The National Map within 5 km, including Green Ridge, Cutthroat Bay. 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 Shadow Mountain Lake across LakeQuality
Planning a trip around Rocky Mountain?
Shadow Mountain Lake is about 12 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
980 measurements from 4 monitoring stations, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Colorado Water Science Center
USGS-CO974 samples · 2020–2024 - Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX6 samples · 2022
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
- Secchi disk depth measurement
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrogen in Water by Pyrolysis Detection
Monitoring station identifiers (4)
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
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