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B

Rush Lake

Otter Tail County, MinnesotaEutrophic

Rush Lake carries a solid B grade — strong on most parameters, with measurements that hold up well across the summer season. The two scored sub-grades — clarity and phosphorus — track close together, so neither one is dragging the average down.

At a TSI of 51, Rush Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake's 68 ft maximum depth is in the upper tier for Minnesota — deep enough for cold-water fish to find refuge in summer. At 5,276 acres, Rush Lake is one of the larger lakes in Otter Tail County, with 13.6 miles of shoreline supporting multiple distinct use patterns. Within Otter Tail County's 97 graded lakes, Rush Lake ranks 72 — below the local median, though not at the bottom.

Rush Lake is on the Minnesota infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. Walleye are documented at Rush Lake, one of 19 fish species on record for the lake. A documented public access point at Rush Lake makes the lake usable for shore fishing, paddle craft, and trailered boats. Ice-out has been recorded 8 times at Rush Lake, with a median around Apr 14. 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 2024-09-22. Grade methodology: LakeGrade methodology.

Reviewed by LakeQuality Editorial Team · Updated

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 6.9 ft. Phosphorus level: 27.5 µg/L. Trophic State Index: 51.

MetricValueGrade
Water Clarity (Secchi Depth)6.9 ftC
Phosphorus27.5 µg/LB
Chlorophyll-a (Algae)No data
Trophic State Index (TSI)51Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Maximum Depth68 ft
Surface Area5.3K acres
Shoreline Length13.6 mi
Littoral Zone63%
Public AccessYes

Fish Species

black bullhead,black crappie,bluegill,bowfin (dogfish),brown bullhead,common carp,green sunfish,hybrid sunfish,lake sturgeon,largemouth bass,northern pike,pumpkinseed,rock bass,shorthead redhorse,tullibee (cisco),walleye,white sucker,yellow bullhead,yellow perch

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

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

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

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

Invasive & Introduced Species

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

zebra mussel

Water Quality Trend: Improving

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

MetricTrendChange/YearYears
Water Clarity Stable+0.014 m/yr5
Phosphorus Improving-2.25 µg/L/yr5
See year-by-year chart →

Ice Season

Historical ice data from Minnesota DNR (8 observations).

Typical Ice-Out
Apr 14
EarliestLatest
Ice-Out2012-03-21 (2012)2022-05-06 (2022)

Most recent ice-out: 2023-05-03

Location

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County Ranking

Ranked #72 of 97 lakes in Otter Tail County

Cleaner Lakes Within 30 Miles

Rush Lake holds Grade B. 2 nearby lakes hold higher grades.

See full comparison →

Nearby Lakes in Otter Tail County

DNR Fisheries Survey Summary

15 surveys on file from MN DNR Fisheries. Most recent: 2025-08-11 (Standard Survey).

Top Species by Catch Rate

SpeciesAvg CPUEAvg Weight
Bluntnose Minnow32.02
LGP30.52
Yellow Perch21.890.12 lb
MMS16.89
Bluegill12.190.16 lb
Spottail Shiner9.84

CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.

Length Distributions

Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.

Yellow Perch

48 fish · 410 in · 2025-08-11
168045678910

Bluegill

152 fish · 38 in · 2025-08-11
60300345678

From the 2025-08-11 survey

Rush Lake is 5,337-acre mesotrophic (moderately fertile) lake located in central Otter Tail County two miles north of Ottertail, MN. Rush Lake is part of the Otter Tail River Watershed. The Otter Tail River inlet is located along the north shoreline while the outlet is located along the southwest shoreline of the…

Source: MN DNR LakeFinder Fisheries Lake Survey

DNR Reports & Resources

Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Rush Lake. 3 reports on file.

Reservoir Info (USACE NID)

Rush Lake is a man-made reservoir impounded by the Rush Lake (completed 1937), built primarily for recreation on the Otter Tail River; gravity-type dam, 8 ft tall and 105 ft long.

Surface area
5,233 ac
Normal storage
52,330 ac-ft
Max storage
78,345 ac-ft
Drainage area
669.6 sq mi
Hazard class
Low
Owner
MNDNR-EWR

Source: USACE National Inventory of Dams, NID ID MN00211 · Operator website

EPA Impairment Status

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

Causes of impairment

Mercury

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

Source: EPA ATTAINS assessment unit MN56-0141-00 · 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

Ice data from Minnesota DNR Climate

Most recent sample: 2024-09-22

Monitoring stations: 3