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F

Mcknight Lake

Carver County, MinnesotaHypereutrophic

Mcknight Lake earns an F: 149 µg/L of phosphorus and clarity at 2.3 ft signal heavy nutrient loading from the surrounding watershed. With clarity and phosphorus scored, the sub-grades cluster within a letter of each other, pointing to stable conditions rather than one specific stressor.

The hypereutrophic status — TSI 71 — reflects sustained heavy nutrient loading from the surrounding watershed and frequent algal pressure. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake is compact at 31 acres, with partial shoreline records and little volume to buffer nutrient inputs. Mcknight Lake ranks 33 of 40 in Carver County — at the lower end of the locally monitored distribution.

No invasive species are currently listed at Mcknight Lake — the lake remains off the Minnesota infested-waters roster. 3 fish species are on record, with panfish making up the recreational core. The lake lacks a documented public access point, so visitor use is limited. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.

Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-23. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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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 2.3 ft of visibility. Phosphorus level: 149 µg/L. Trophic State Index: 71.

MetricValueGrade
Water Clarity (Secchi Depth)2.3 ftF
Phosphorus149 µg/LF
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)71Hypereutrophic

Very high nutrients, dense algae, poor clarity

Lake Details

CharacteristicValue
Surface Area31 acres
Public AccessNo

Fish Species

black bullhead,bluegill,green sunfish

Click a species to see all Minnesota and Wisconsin lakes where it is found.

→ Best fishing times for Mcknight Lake (14-day solunar calendar)

→ Is it safe to eat fish from Mcknight Lake? (mercury & PFAS guide)

Mcknight Lake fishing regulations (limits, seasons, special rules)

Water Quality Trend: Stable

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Improving+0.012 m/yr5
Phosphorus Declining+6.15 µg/L/yr5
See year-by-year chart →

Location

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County Ranking

Ranked #33 of 40 lakes in Carver County

Cleaner Lakes Within 30 Miles

Mcknight Lake holds Grade F. 3 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Carver County

Hypereutrophic Lakes in Minnesota

Reservoir Info (USACE NID)

Mcknight Lake is a man-made reservoir impounded by the Mcknight Lake, built primarily for flood risk reduction on the Chaska East Creek; earth-type dam, 8 ft tall.

Surface area
31 ac
Normal storage
82 ac-ft
Max storage
82 ac-ft
Drainage area
5.93 sq mi
Hazard class
Low
Owner
City of Chaska

Source: USACE National Inventory of Dams, NID ID MN01263 · Operator website

EPA Impairment Status

Mcknight Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Nutrients (phosphorus, nitrogen)

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit MN10-0216-00 · 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

Lake details from Minnesota DNR LakeFinder

Most recent sample: 2024-10-23

Monitoring stations: 2