Benton Lake
Carver County, MinnesotaHypereutrophic
Benton Lake grades an F: every scored parameter (clarity and phosphorus) rates poorly, placing it among the most stressed lakes monitored in Minnesota. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.
Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Benton Lake sits at rank 30 of 40 in Carver County, in the lower half of the local distribution.
No invasive species are currently listed at Benton Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Benton Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Benton Lake — most use is by shoreline residents and their guests. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-22. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 0.8 ft of visibility. Phosphorus level: 171 µg/L. Trophic State Index: 80.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.8 ft | F |
| Phosphorus | 171 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 80 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.046 m/yr | 5 |
| Phosphorus | ↑ Improving | -33.9 µg/L/yr | 5 |
Location
County Ranking
Ranked #30 of 40 lakes in Carver County
Cleaner Lakes Within 30 Miles
Benton Lake holds Grade F. 3 nearby lakes hold higher grades.
- CBurandt LakeCarver County · mi · Two grade letters higher (F → C)
- DMyers LakeCarver County · mi · Higher grade (F → D)
- DReitz LakeCarver County · mi · Higher grade (F → D)
Nearby Lakes in Carver County
More Minnesota Lake Rankings
State Parks Near Benton Lake
Other Grade F Lakes in Minnesota
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Benton Lake. 1 report on file.
- —Fish Stocking History — BentonFish Stocking History · MN DNR LakeFinder
EPA Impairment Status
Benton Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN10-0069-00 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-10-22
Monitoring stations: 2