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F

Locke Lake

Anoka County, MinnesotaEutrophic

On the LakeGrade rubric Locke Lake fails the cutoffs — a TSI of 67 and persistent algal pressure put it in the bottom tier. clarity and phosphorus rate similarly, so there is no obvious single lever to pull on watershed management.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. 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 23 acres, with partial shoreline records and little volume to buffer nutrient inputs. Locke Lake ranks 22 of 24 in Anoka County — at the lower end of the locally monitored distribution.

Eurasian watermilfoil has been documented at Locke Lake, requiring shoreline management to keep dense mats from crowding native vegetation. The state fisheries records do not list documented species for Locke Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. A documented public access point at Locke Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. 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 2021-09-27. 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 3 ft of visibility. Phosphorus level: 107 µg/L. Trophic State Index: 67.

MetricValueGrade
Water Clarity (Secchi Depth)3 ftF
Phosphorus107 µg/LF
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)67Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Surface Area23 acres
Public AccessYes

Invasive & Introduced Species

Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.

Eurasian watermilfoil

Location

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County Ranking

Ranked #22 of 24 lakes in Anoka County

Cleaner Lakes Within 30 Miles

Locke Lake holds Grade F. 5 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Anoka County

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Locke Lake. 1 report on file.

Reservoir Info (USACE NID)

Locke Lake is a man-made reservoir impounded by the Locke Lake (completed 1956), built primarily for recreation on the Rice Creek; concrete-type dam, 25 ft tall and 100 ft long.

Surface area
23 ac
Normal storage
200 ac-ft
Max storage
320 ac-ft
Drainage area
200 sq mi
Hazard class
Significant
Owner
City of Fridley

Source: USACE National Inventory of Dams, NID ID MN00396 · Operator website

EPA Impairment Status

Locke 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 MN02-0075-01 · Official waterbody report · Matched by proximity (2.9 km)

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: 2021-09-27

Monitoring stations: 1