Otter Lake
Otter Lake in Ramsey County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.5 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 21 ft. Surface area: 302.21 acres.
- Clarity
- 11.5 ft
- Typical in August
- 72°F
- Max depth
- 21 ft
- Area
- 302 acres
- Type
- Mesotrophic
- Trend
- ↑ Improving
- Public access
- Yes
- Ice-out
- Apr 3
- Open water
- 225 days
Next lake in Ramsey County
Otter Lake is a 302-acre mesotrophic lake in Ramsey County, Minnesota with a maximum depth of 21 feet (6-foot average). Water quality is graded A based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 43 other monitored lakes in Ramsey County, Otter Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-11. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyLow algae
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 11.5 ft. Phosphorus level: 22 µg/L. Chlorophyll-a: 2.7 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11.5 ft | Not graded |
| Phosphorus | 22 µg/L | Good |
| Chlorophyll-a (Algae) | 2.7 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Otter Lake
Compare lakeside cabins, hotels, and vacation rentals near Otter Lake in Ramsey 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.
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Water Temperature
Otter Lake typically sits around 72°F at the surface in August. Summer average is about 70°F. Usually warmest in Jul (about 72°F) and coldest in Mar (about 40°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 491 field readings (2010–2025) via the EPA Water Quality Portal. See the full Otter Lake water temperature breakdown →
Blue-Green Algae (Cyanobacteria)
There’s no recent EPA CyAN cyanobacteria estimate for Otter Lake — clouds, ice, or an off-season gap in coverage. The most recent reading was high (151,356 cells/mL) on November 16, 2025.
Blue-green algae can appear and clear within days, so check your state’s current advisory before swimming. EPA CyAN ↗
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 21 ft |
| Average Depth | 6 ft |
| Surface Area | 302 acres |
| Shoreline Length | 4.2 mi |
| Littoral Zone | 99% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Bald Eagle-Otter Lake Regional ParkPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Otter 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
8 surveys on file from MN DNR Fisheries. Most recent: 2019-06-10 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Bullhead | 25.41 | 0.35 lb |
| Bluegill | 12.46 | 0.21 lb |
| Brown Bullhead | 10.83 | 0.53 lb |
| Northern Pike | 8.84 | 1.49 lb |
| Hybrid Sunfish | 3.59 | 0.26 lb |
| Pumpkinseed | 2.85 | 0.18 lb |
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.
Black Bullhead
Bluegill
Northern Pike
Hybrid Sunfish
From the 2019-06-10 survey
Otter Lake is a 332 acre highly fertile lake assigned to lake class 39. The maximum depth is 21 feet but the vast majority of the lake is 15 feet or shallower. The lack of deep water habitat has resulted in this lake being historically susceptible to winter kills. An aeration system was installed in 2002 and is…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Otter Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OtterFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — OtterFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — OtterPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↑ Improving
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.226 m/yr | 6 |
| Phosphorus | → Stable | -0.17 µg/L/yr | 6 |
| Chlorophyll-a | ↑ Improving | -0.6 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (37 observations).
Estimated open water season: 225 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2000-03-07 (2000) | 2018-04-29 (2018) |
| Ice-In | 2019-11-09 (2019) | 2017-12-10 (2017) |
Most recent ice-out: 2026-03-27
EPA Impairment Status
Otter Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN02-0003-00 · Official waterbody report
County Ranking
Ranked #2 of 44 lakes in Ramsey County
Nearby Lakes in Ramsey County
Frequently asked questions about Otter Lake
What is the water quality grade for Otter Lake?
- Otter Lake in Ramsey County, Minnesota has a water quality grade of A (Excellent). Water clarity: 11.5 ft visibility. Phosphorus: 22 µg/L. Chlorophyll-a (algae): 2.7 µg/L. Maximum depth: 21 ft. Surface area: 302.21 acres.
Is Otter Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Otter Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Otter Lake?
- Otter Lake typically sits around 72°F at the surface in August, from 491 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Otter Lake?
- Otter Lake has a maximum depth of 21 feet and an average depth of 6 feet. The lake covers 302.21 acres.
What fish are in Otter Lake?
- Fish species found in Otter Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, yellow bullhead. Otter Lake is located in Ramsey County, Minnesota.
When does Otter Lake thaw?
- Otter Lake typically has ice-out around Apr 3. Ice typically forms around Nov 14. The open water season is approximately 225 days.
Does Otter Lake have blue-green algae?
- There is no recent EPA CyAN cyanobacteria estimate for Otter Lake (clouds, ice, or an off-season gap). The most recent reading was high (151,356 cells/mL). Blue-green algae can appear and clear within days, so check Minnesota's current advisory before swimming.
Are there boat ramps on Otter Lake?
- Otter Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Bald Eagle-Otter Lake Regional Park. Public access is listed as yes.
Explore Otter 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 Ramsey County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its grade
Moderate nutrients, good water quality
Minnesota's cleanest and most-polluted lakes, ranked
More Minnesota Lake Rankings
State Parks Near Otter Lake
Other Grade A Lakes in Minnesota
Mesotrophic Lakes in Minnesota
Where this data comes from
295 measurements from 2 monitoring stations, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA295 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- Phosphorus by Two Reagent Colorimetry
Monitoring station identifiers (2)
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