Horsetooth Reservoir
Larimer County, Colorado1,817 acresView mapDirections
No nutrient or algae sampling on record from Colorado WQCD for this lake.
- Impaired · Mercury
- 200 ft max depth
Horsetooth Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Maximum depth: 200 ft. Surface area: 1817 acres.
Horsetooth Reservoir is a 1,817-acre lake in Larimer County, Colorado with a maximum depth of 200 feet.
Source: EPA Water Quality Portal sampling records, CDPHE. Methodology: how these readings are compared.
What Horsetooth Reservoir is good for
From access and monitoring records, not editorial picks.
- Deep water200 ft surveyed max depth
- Big water1,817 acres
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Horsetooth 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 Horsetooth 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 Horsetooth Reservoir
These are the measurements Colorado WQCD publishes for Horsetooth 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. TSI undefined.
Ask about Horsetooth Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
200 ft
Surface area
1,817 acres
Shoreline
26.4 mi
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Fishing Horsetooth Reservoir
EPA Impairment Status
Horsetooth 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 COSPCP14_A · Official waterbody report
Nearby Lakes in Larimer County
Frequently asked questions about Horsetooth Reservoir
Where is Horsetooth Reservoir?
- Horsetooth 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 Horsetooth Reservoir?
- Horsetooth Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Maximum depth: 200 ft. Surface area: 1817 acres.
Is Horsetooth Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Horsetooth 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 Horsetooth Reservoir?
- Horsetooth Reservoir has a maximum depth of 200 feet. The lake covers 1817 acres.
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Where this data comes from
Measurements for Horsetooth Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database