Ennis Lake
Madison County, Montana3,758 acresView mapDirections
No nutrient or algae sampling on record from Montana DEQ for this lake.
- Impaired · Habitat alterations
- 20 ft max depth
Ennis Lake in Madison County, Montana has water-quality measurements published by Montana DEQ, shown here as reported. Maximum depth: 20 ft. Surface area: 3758 acres.
Ennis Lake is a 3,758-acre lake in Madison County, Montana with a maximum depth of 20 feet.
Source: EPA Water Quality Portal sampling records, Montana DEQ. Methodology: how these readings are compared.
What Ennis Lake is good for
From access and monitoring records, not editorial picks.
- Big water3,758 acres
Swimming conditions
No readingNot rated
Nutrient and algae readings are not a swimming clearance. Ennis Lake is listed impaired under Clean Water Act §303(d) (IR 5) for habitat alterations, hydrologic alteration, metals (other than mercury). Check local advisories before you swim.
Whether Ennis Lake is safe to swim in today is a call for the Montana Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Ennis Lake
These are the measurements Montana DEQ publishes for Ennis Lake, 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 Ennis Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
20 ft
Surface area
3,758 acres
Shoreline
12.8 mi
Stays via Stay22
Stays near Ennis Lake
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Fishing Ennis Lake
EPA Impairment Status
Ennis Lake is officially listed as impaired under Clean Water Act §303(d) in the 2021 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Drinking water, Aquatic life.
Source: EPA ATTAINS assessment unit MT41F005_030 · Official waterbody report
Nearby Lakes in Madison County
Frequently asked questions about Ennis Lake
Where is Ennis Lake?
- Ennis Lake is a lake in Madison County, Montana. Its water-quality measurements are published by Montana DEQ and shown on this page as reported.
What is the water quality of Ennis Lake?
- Ennis Lake in Madison County, Montana has water-quality measurements published by Montana DEQ, shown here as reported. Maximum depth: 20 ft. Surface area: 3758 acres.
Is Ennis Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Ennis Lake is listed impaired under Clean Water Act §303(d) (IR 5) for habitat alterations, hydrologic alteration, metals (other than mercury). Check local advisories before you swim.
How deep is Ennis Lake?
- Ennis Lake has a maximum depth of 20 feet. The lake covers 3758 acres.
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Where this data comes from
Measurements for Ennis Lake 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