Zumbro Lake
Zumbro Lake in Olmsted County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4 ft visibility. Phosphorus: 69 µg/L. Chlorophyll-a (algae): 24.7 µg/L. Maximum depth: 43 ft. Surface area: 714.54 acres.
Minnesota DNR surveys at Zumbro Lake average 26.09 smallmouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated June 14, 2021. Length samples in the latest survey that recorded them ran 7–19 inches. DNR survey details →
- Clarity
- 4 ft
- Typical in August
- 76°F
- Max depth
- 43 ft
- Area
- 715 acres
- Type
- Eutrophic
- Trend
- → Stable
- Public access
- Yes
- Ice-out
- Mar 31
- Open water
- 245 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Zumbro Lake →
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Zumbro Lake is a 715-acre productive, nutrient-rich eutrophic lake in Olmsted County, Minnesota with a maximum depth of 43 feet. Water quality is graded D based on 2 sampling years through 2025. Phosphorus level is declining over recent sampling years. The lake supports 24 documented fish species including black bullhead, black crappie, and bluegill. Public access is available with 1 public boat landing. Compared to the 1 other monitored lakes in Olmsted County, Zumbro Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-08-28. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyAlgae risk
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 4 ft. Phosphorus level: 69 µg/L. Chlorophyll-a: 24.7 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4 ft | Not graded |
| Phosphorus | 69 µg/L | Poor |
| Chlorophyll-a (Algae) | 24.7 µg/L | Poor |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Zumbro Lake
Compare lakeside cabins, hotels, and vacation rentals near Zumbro Lake in Olmsted 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 Zumbro Lake are listed below.
Top-rated places to stay near Zumbro Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Zumbro Lake typically sits around 76°F at the surface in August. Summer average is about 74°F. Usually warmest in Aug (about 76°F) and coldest in Sep (about 68°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 48 field readings (2017–2025) via the EPA Water Quality Portal. See the full Zumbro Lake water temperature breakdown →
Minnesota DNR surveys at Zumbro Lake average 26.09 smallmouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated June 14, 2021. Length samples in the latest survey that recorded them ran 7–19 inches.
A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Zumbro Lake D from EPA Water Quality Portal chemistry, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
13 surveys on file from MN DNR Fisheries. Most recent: 2021-06-14 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg catch rate (CPUE) | Avg Weight |
|---|---|---|
| Smallmouth Bass | 26.09 | 0.94 lb |
| Largemouth Bass | 17.09 | 0.85 lb |
| Channel Catfish | 7.79 | 2.23 lb |
| Walleye | 4.66 | 1.77 lb |
| Golden Redhorse | 4.60 | 1.89 lb |
| Yellow Perch | 4.58 | 0.19 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE means more abundant in standardized sampling. This is not a weekly bite report.
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.
Smallmouth Bass
Largemouth Bass
Channel Catfish
Walleye
From the 2021-06-14 survey
Lake Zumbro is a large reservoir on the Zumbro River. It is a popular recreation and fishing lake due to its proximity to Rochester, MN. The primary gamefish in the reservoir are Bluegill, Black Crappie, Channel Catfish, Largemouth Bass, Smallmouth Bass, and Northern Pike. A walleye stocking program was initiated in…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Zumbro Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — ZumbroFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — ZumbroFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — ZumbroPublic Water Access Sites · MN DNR LakeFinder
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 43 ft |
| Surface Area | 715 acres |
| Shoreline Length | 22.8 mi |
| Littoral Zone | 37% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- PonderosaPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Zumbro 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.
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.025 m/yr | 6 |
| Phosphorus | ↓ Declining | +2.32 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -1.49 µg/L/yr | 3 |
Ice Season
Historical ice data from Minnesota DNR (51 observations).
Estimated open water season: 245 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2017-02-22 (2017) | 2018-04-25 (2018) |
| Ice-In | 2014-11-13 (2014) | 2015-12-28 (2015) |
Most recent ice-out: 2026-03-22
Reservoir Info (USACE NID)
Zumbro Lake is a man-made reservoir impounded by the Lake Zumbro (completed 1919), built primarily for hydroelectric on the Zumbro River; gravity-type dam, 65 ft tall and 570 ft long.
- Normal storage
- 20,000 ac-ft
- Max storage
- 35,000 ac-ft
- Drainage area
- 845 sq mi
- Hazard class
- High
- Owner
- City of Rochester
Source: USACE National Inventory of Dams, NID ID MN00358 · Operator website
EPA Impairment Status
Zumbro 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 MN55-0004-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Zumbro Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Camp Victory WwtpZumbro Falls · 2.6 mi away · NPDES MN0067032Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
County Ranking
Ranked #2 of 2 lakes in Olmsted County
Nearby Lakes With Higher Grades
Zumbro 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.
See full comparison →Nearby Lakes in Olmsted County
Frequently asked questions about Zumbro Lake
Where is Zumbro Lake?
- Zumbro Lake is a lake in Olmsted County, Minnesota. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Zumbro Lake?
- Zumbro Lake in Olmsted County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 4 ft visibility. Phosphorus: 69 µg/L. Chlorophyll-a (algae): 24.7 µg/L. Maximum depth: 43 ft. Surface area: 714.54 acres.
Is Zumbro 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. Zumbro Lake has a water quality grade of D (Nutrient-rich). Algae concentration (chlorophyll-a) is 24.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Zumbro Lake?
- Zumbro Lake typically sits around 76°F at the surface in August, from 48 EPA Water Quality Portal field readings (2017–2025). That is a typical value for the month, not a live reading.
How deep is Zumbro Lake?
- Zumbro Lake has a maximum depth of 43 feet. The lake covers 714.54 acres.
What fish are in Zumbro Lake?
- Fish species found in Zumbro Lake include black bullhead, black crappie, bluegill, channel catfish, common carp, freshwater drum, golden redhorse, hybrid sunfish, largemouth bass, muskellunge, northern pike, quillback, redhorse, river carpsucker, river redhorse, shorthead redhorse, silver redhorse, smallmouth bass, walleye, white bass, white crappie, white sucker, yellow bullhead, yellow perch. Zumbro Lake is located in Olmsted County, Minnesota.
What did the DNR fisheries survey find at Zumbro Lake?
- Minnesota DNR surveys at Zumbro Lake average 26.09 smallmouth bass per unit of sampling effort (CPUE) across 13 surveys. The most recent is a Targeted Survey dated June 14, 2021. Length samples in the latest survey that recorded them ran 7–19 inches. A DNR fisheries survey reports fish abundance and catch rates, not a water-quality grade. LakeQuality grades Zumbro Lake D from EPA Water Quality Portal chemistry, and the water-quality trend over 6 years of monitoring is stable. Catch rate is not a swim clearance and is not a weekly bite report.
When does Zumbro Lake thaw?
- Zumbro Lake typically has ice-out around Mar 31. Ice typically forms around Dec 1. The open water season is approximately 245 days.
Are there boat ramps on Zumbro Lake?
- Zumbro Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Ponderosa. Public access is listed as yes.
Explore Zumbro Lake across LakeQuality
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Species activity outlook by water temperature and season
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Where this data comes from
230 measurements from 6 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
MNPCA230 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
Monitoring station identifiers (6)
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
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