Forest Lake
Forest Lake in Washington County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5.1 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 16.5 µg/L. Maximum depth: 37 ft. Surface area: 2270.93 acres.
- Clarity
- 5.1 ft
- Typical in August
- 70°F
- Max depth
- 37 ft
- Area
- 2,271 acres
- Type
- Eutrophic
- Public access
- Yes
- Ice-out
- Apr 9
- Open water
- 235 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Forest Lake →
Next lake in Washington County
Free interactive depth-contour map of Forest Lake, reaching a maximum surveyed depth of 35 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Forest Lake is a 2,271-acre productive, nutrient-rich eutrophic lake in Washington County, Minnesota with a maximum depth of 37 feet. Water quality is graded D based on 2 sampling years through 2024. The lake supports 18 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 74 other monitored lakes in Washington County, Forest Lake ranks #54 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-17. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 5.1 ft. Phosphorus level: 28 µg/L. Chlorophyll-a: 16.5 µg/L. Trophic State Index: 55.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.1 ft | Not graded |
| Phosphorus | 28 µg/L | Fair |
| Chlorophyll-a (Algae) | 16.5 µg/L | Poor |
| Trophic State Index (TSI) | 55 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Forest Lake
Compare lakeside cabins, hotels, and vacation rentals near Forest Lake in Washington County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Forest Lake are listed below.
Top-rated places to stay near Forest Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Forest Lake typically sits around 70°F at the surface in August. Summer average is about 69°F. Usually warmest in Jul (about 70°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 171 field readings (2011–2024) via the EPA Water Quality Portal. See the full Forest Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 37 ft |
| Surface Area | 2,271 acres |
| Shoreline Length | 15.7 mi |
| Littoral Zone | 67% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Forest Lake #2 - Willow PointPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Forest Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
20 surveys on file from MN DNR Fisheries. Most recent: 2025-07-07 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 32.29 | 0.11 lb |
| Black Crappie | 8.40 | 0.17 lb |
| Spottail Shiner | 7.16 | — |
| Yellow Perch | 7.00 | 0.1 lb |
| Pumpkinseed | 6.76 | 0.16 lb |
| BKF | 6.00 | — |
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.
Bluegill
Black Crappie
Yellow Perch
Pumpkinseed
From the 2025-07-07 survey
Forest Lake is a 2,251 acre lake comprised of three distinct basins and assigned to lake class 24. There are three public boat accesses available on the lake resulting in high recreational use. Zebra Mussels were discovered in 2015. The primary management species in the lake are Walleye and Muskellunge both of which…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Forest Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — ForestFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — ForestFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ForestPublic Water Access Sites · MN DNR LakeFinder
Ice Season
Historical ice data from Minnesota DNR (142 observations).
Estimated open water season: 235 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2013-05-02 (2013) |
| Ice-In | 1991-11-04 (1991) | 2001-12-20 (2001) |
Most recent ice-out: 2026-03-31
EPA Impairment Status
Forest Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN82-0159-00 · Official waterbody report
County Ranking
Ranked #54 of 75 lakes in Washington County
Nearby Lakes With Higher Grades
Forest Lake holds Grade D. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Washington County
Frequently asked questions about Forest Lake
What is the water quality grade for Forest Lake?
- Forest Lake in Washington County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5.1 ft visibility. Phosphorus: 28 µg/L. Chlorophyll-a (algae): 16.5 µg/L. Maximum depth: 37 ft. Surface area: 2270.93 acres.
Is Forest Lake safe to swim in?
- Nutrients and algae run higher than average — check local advisories before swimming, and skip the water if you see scum. Forest Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 16.5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Forest Lake?
- Forest Lake typically sits around 70°F at the surface in August, from 171 EPA Water Quality Portal field readings (2011–2024). That is a typical value for the month, not a live reading.
How deep is Forest Lake?
- Forest Lake has a maximum depth of 37 feet. The lake covers 2270.93 acres.
What fish are in Forest Lake?
- Fish species found in Forest Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, muskellunge, northern pike, pumpkinseed, rock bass, walleye, white crappie, white sucker, yellow bullhead, yellow perch. Forest Lake is located in Washington County, Minnesota.
When does Forest Lake thaw?
- Forest Lake typically has ice-out around Apr 9. Ice typically forms around Nov 30. The open water season is approximately 235 days.
Are there boat ramps on Forest Lake?
- Forest Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Forest Lake #2 - Willow Point. Public access is listed as yes.
Explore Forest Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
Fish species and top-graded lakes across Minnesota
Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Lakes in the St. Croix Watershed, ranked by water quality
High nutrients, frequent algae, reduced clarity
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Forest Lake
Other Grade D Lakes in Minnesota
Eutrophic Lakes in Minnesota
Compare Forest Lake With Nearby Lakes
Where this data comes from
173 measurements from 4 monitoring stations, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA173 samples · 2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Analysis of Chlorophyll in Periphyton and Plankton
Monitoring station identifiers (4)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory
Ice data from Minnesota DNR Climate