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LakeQuality
B

Headquarters Bay Lake

Cass County, MinnesotaMesotrophic

Headquarters Bay Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The lake's weakest score is on Secchi depth — the water looks more turbid than its phosphorus number alone would predict.

A TSI near 46 places Headquarters Bay Lake in the mesotrophic band — moderate productivity, with seasonal swings between clearer spring water and richer late-summer conditions. 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. Within the 133 graded lakes of Cass County, Headquarters Bay Lake sits at rank 104, near the bottom of the county list.

Zebra mussel presence at Headquarters Bay Lake means the lake's clarity numbers carry an asterisk — filtered water is not the same as nutrient-poor water. The state fisheries records do not list documented species for Headquarters Bay Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. Public access is available — the lake is on the Minnesota PCA public-access list. The lake has a long ice-out record — 71 observations on file, with a median ice-out around Apr 28. 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 2023-09-07. Grade methodology: LakeGrade methodology.

Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 7.5 ft. Chlorophyll-a: 3.6 µg/L. Trophic State Index: 46.

MetricValueGrade
Water Clarity (Secchi Depth)7.5 ftC
PhosphorusNo data
Chlorophyll-a (Algae)3.6 µg/LA
Trophic State Index (TSI)46Mesotrophic

Moderate nutrients, good water quality

Invasive Species

Eurasian watermilfoilstarry stonewortzebra mussel

Water Quality Trend: Stable

Based on 2 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.52 m/yr2
Chlorophyll-a Improving-1 µg/L/yr2

Ice Season

Historical ice data from Minnesota DNR (74 observations).

Typical Ice-Out
Apr 28
Typical Ice-In
Nov 14

Estimated open water season: 200 days

EarliestLatest
Ice-Out1945-04-09 (1945)1950-05-23 (1950)
Ice-In2018-11-13 (2018)2021-11-25 (2021)

Most recent ice-out: 2022-05-08

Location

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County Ranking

Ranked #104 of 133 lakes in Cass County

Nearby Lakes in Cass County

State Parks Near Headquarters Bay Lake

DNR Reports & Resources

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

Data Sources

Water quality data from the EPA Water Quality Portal

Grading methodology based on Metropolitan Council standards

Ice data from Minnesota DNR Climate

Most recent sample: 2023-09-07

Monitoring stations: 1