Carter Reservoir
Larimer County, Colorado3,551 acresView mapDirections
No nutrient or algae sampling on record from Colorado WQCD for this lake.
- Impaired · Mercury
- 81 ft max depth
- Limited data
Carter Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Surface area: 3551 acres.
Carter Reservoir is a 3,551-acre lake in Larimer County, Colorado with an estimated average depth of about 81 feet.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2022-10-27. Methodology: how these readings are compared.
Carter Reservoir covers about 3,600 acres in Larimer County. For a place on the water, look through cabin and lake-house rentals near Carter Reservoir on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Carter Reservoir is good for
From access and monitoring records, not editorial picks.
- Big water3,551 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Carter Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury). Check local advisories before you swim.
Whether Carter 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 Carter Reservoir
These are the measurements Colorado WQCD publishes for Carter Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data.
Ask about Carter Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~81 ft est.
Surface area
3,551 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 Carter Reservoir.
Lake Size & Watershed
Watershed (drainage) area
2 sq mi
HydroLAKES / HydroSHEDS
Shoreline
6.8 mi
HydroLAKES / HydroSHEDS
Elevation
5,758 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.
Stays via Stay22
Stays near Carter Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Carter Reservoir in Larimer 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.
Top-rated places to stay near Carter Reservoir
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Colorado’s top lakes →
Follow Carter Reservoir’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Carter Reservoir
Reservoir Info (USACE NID)
Carter Reservoir is a man-made reservoir impounded by the Carter Lake Dam 1 (completed 1952), built primarily for hydroelectric on the Big Thompson River Os; earth-type dam, 214 ft tall and 1,235 ft long.
- Surface area
- 3,551 ac
- Normal storage
- 112,228 ac-ft
- Max storage
- 116,837 ac-ft
- Drainage area
- 18.03 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Hydroelectric;Irrigation;Water Supply.
Source: USACE National Inventory of Dams, NID ID CO01650 · Operator website
EPA Impairment Status
Carter 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, Aquatic life.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit COSPBT11_A · Official waterbody report
Nearby Lakes in Larimer County
Frequently asked questions about Carter Reservoir
Where is Carter Reservoir?
- Carter Reservoir is a lake in Larimer County, Colorado. Its water-quality measurements are published by Colorado WQCD and shown on this page as reported.
What is the water quality of Carter Reservoir?
- Carter Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Surface area: 3551 acres.
Is Carter Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Carter Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury). Check local advisories before you swim.
How deep is Carter Reservoir?
- No published bathymetric survey covers Carter Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 81 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 3551 acres.
Explore Carter Reservoir across LakeQuality
Planning a trip around Rocky Mountain?
Carter Reservoir is about 25 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
Where this data comes from
6 measurements from 2 monitoring stations, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX6 samples · 2022
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)
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)