Sullivan Lake
Sullivan Lake in Morrison County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.8 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 5 µg/L. Maximum depth: 57 ft. Surface area: 1103.4 acres.
- Clarity
- 10.8 ft
- Typical in August
- 67°F
- Max depth
- 57 ft
- Area
- 1,103 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 19
- Open water
- 225 days
Next lake in Morrison County
Free interactive depth-contour map of Sullivan Lake, reaching a maximum surveyed depth of 50 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Sullivan Lake is a 1,103-acre mesotrophic lake in Morrison County, Minnesota with a maximum depth of 57 feet (18-foot average). Water quality is graded A based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. The lake supports 18 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 4 public boat landings. Compared to the 7 other monitored lakes in Morrison County, Sullivan Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-09-24. 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 10.8 ft. Phosphorus level: 14 µg/L. Chlorophyll-a: 5 µg/L. Trophic State Index: 44.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.8 ft | Not graded |
| Phosphorus | 14 µg/L | Good |
| Chlorophyll-a (Algae) | 5 µg/L | Good |
| Trophic State Index (TSI) | 44 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Sullivan Lake
Compare lakeside cabins, hotels, and vacation rentals near Sullivan Lake in Morrison 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
Sullivan Lake typically sits around 67°F at the surface in August. Summer average is about 65°F. Usually warmest in Aug (about 67°F) and coldest in May (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 181 field readings (2016–2025) via the EPA Water Quality Portal. See the full Sullivan Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 57 ft |
| Average Depth | 17.6 ft |
| Surface Area | 1,103 acres |
| Shoreline Length | 7.7 mi |
| Littoral Zone | 51% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Platte LakePublic
- Sullivan Lake (West)Public
- Sullivan Lake (East)Public
- Round LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Sullivan Lake
DNR Fisheries Survey Summary
30 surveys on file from MN DNR Fisheries. Most recent: 2025-06-23 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| CNM | 19.87 | — |
| Bluegill | 15.74 | 0.22 lb |
| Walleye | 10.64 | 1.49 lb |
| Largemouth Bass | 8.88 | 1.51 lb |
| Bluntnose Minnow | 8.14 | — |
| Yellow Perch | 6.80 | 0.15 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.
Bluegill
Walleye
Largemouth Bass
Yellow Perch
From the 2025-06-23 survey
A targeted survey of nearshore fish species in Sullivan Lake, was conducted on June 23rd-24th, 2025, by Area Fisheries staff. Sampling sites were evenly spaced around the lake, and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine, where possible. Backpack electrofishing was…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Sullivan Lake. 5 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — SullivanFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Sullivan (0241)Aquatic Plant Report · MN DNR LakeFinder
- —Aquatic Plant Report — Sullivan (1926)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — SullivanFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — SullivanPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.13 m/yr | 4 |
| Phosphorus | ↓ Declining | +0.66 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +0.65 µg/L/yr | 4 |
Ice Season
Historical ice data from Minnesota DNR (33 observations).
Estimated open water season: 225 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2012-03-19 (2012) | 1996-04-29 (1996) |
| Ice-In | 2023-11-27 (2023) | 2001-12-20 (2001) |
Most recent ice-out: 2023-04-29
EPA Impairment Status
Sullivan 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 MN49-0016-00 · Official waterbody report
County Ranking
Ranked #1 of 8 lakes in Morrison County
Nearby Lakes in Morrison County
Frequently asked questions about Sullivan Lake
What is the water quality grade for Sullivan Lake?
- Sullivan Lake in Morrison County, Minnesota has a water quality grade of A (Excellent). Water clarity: 10.8 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 5 µg/L. Maximum depth: 57 ft. Surface area: 1103.4 acres.
Is Sullivan Lake safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Sullivan Lake has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 5 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Sullivan Lake?
- Sullivan Lake typically sits around 67°F at the surface in August, from 181 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Sullivan Lake?
- Sullivan Lake has a maximum depth of 57 feet and an average depth of 17.6 feet. The lake covers 1103.4 acres.
What fish are in Sullivan Lake?
- Fish species found in Sullivan Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, rock bass, smallmouth bass, tullibee (cisco), walleye, white sucker, yellow bullhead, yellow perch. Sullivan Lake is located in Morrison County, Minnesota.
When does Sullivan Lake thaw?
- Sullivan Lake typically has ice-out around Apr 19. Ice typically forms around Nov 30. The open water season is approximately 225 days.
Are there boat ramps on Sullivan Lake?
- Sullivan Lake has 4 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Platte Lake, Sullivan Lake (West), Sullivan Lake (East), Round Lake. Public access is listed as yes.
Explore Sullivan 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 Morrison 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
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State Parks Near Sullivan Lake
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Mesotrophic Lakes in Minnesota
Compare Sullivan Lake With Nearby Lakes
Where this data comes from
57 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA57 samples · 2020–2024
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (1)
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