St Olaf Lake
St Olaf Lake in Waseca County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 33 ft. Surface area: 91.2 acres.
- Clarity
- 5 ft
- Typical in August
- 68°F
- Max depth
- 33 ft
- Area
- 91 acres
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Mar 31
- Open water
- 247 days
Next lake in Waseca County
Why St Olaf Lake has no grade
We grade a lake only when its monitoring record clears the evidence bar: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For St Olaf Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by MPCA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
St Olaf Lake is a 91-acre lake in Waseca County, Minnesota with a maximum depth of 33 feet. Overall water quality is declining over recent sampling years. The lake supports 11 documented fish species including black crappie, bluegill, and common carp. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-16. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for St Olaf Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 5 ft. Trophic State Index: 54.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 54 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near St Olaf Lake
Compare lakeside cabins, hotels, and vacation rentals near St Olaf Lake in Waseca 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.
Top-rated places to stay near St Olaf Lake
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Water Temperature
St Olaf Lake typically sits around 68°F at the surface in August. Summer average is about 66°F. Usually warmest in Jul (about 68°F) and coldest in Apr (about 47°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 708 field readings (2010–2019) via the EPA Water Quality Portal. See the full St Olaf Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 33 ft |
| Surface Area | 91 acres |
| Shoreline Length | 1.6 mi |
| Littoral Zone | 56% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- St. Olaf LakePublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing St Olaf Lake
DNR Fisheries Survey Summary
11 surveys on file from MN DNR Fisheries. Most recent: 2022-06-20 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluntnose Minnow | 58.11 | — |
| Bluegill | 55.88 | 0.14 lb |
| Largemouth Bass | 27.78 | 1.18 lb |
| Black Crappie | 14.48 | 0.18 lb |
| JND | 11.88 | — |
| Black Bullhead | 10.12 | 0.58 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
Largemouth Bass
Black Crappie
Black Bullhead
From the 2022-06-20 survey
St Olaf Lake is a 91-acre lake located approximately 3.5 miles east of the town of New Richland in Waseca County. The county-owned public access is located on the north shore off County Highway 8. St Olaf Lake has a maximum depth of 33 feet, with approximately 55% of the lake less than 15 feet. St Olaf Lake is…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for St Olaf Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — St. OlafFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — St. OlafFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — St. OlafPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.049 m/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (25 observations).
Estimated open water season: 247 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2013-04-22 (2013) |
| Ice-In | 2014-11-15 (2014) | 2004-12-14 (2004) |
Most recent ice-out: 2026-03-21
Reservoir Info (USACE NID)
St Olaf Lake is a man-made reservoir impounded by the St. Olaf Lake (completed 1940), built primarily for recreation on the Le Sueur River-TR; other-type dam, 7 ft tall and 21 ft long.
- Surface area
- 90 ac
- Normal storage
- 1,245 ac-ft
- Max storage
- 1,494 ac-ft
- Drainage area
- 0.6 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN00109 · Operator website
EPA Impairment Status
St Olaf 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 MN81-0003-00 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of St Olaf Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- New Richland WwtpNew Richland · 4.5 mi away · NPDES MN0021032Recent violation
- Cargill Animal NutritionNew Richland · 4.5 mi away · NPDES MN0071919
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.
Graded lakes near St Olaf Lake
St Olaf Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Waseca County
Frequently asked questions about St Olaf Lake
What is the water quality grade for St Olaf Lake?
- St Olaf Lake in Waseca County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5 ft visibility. Maximum depth: 33 ft. Surface area: 91.2 acres.
Is St Olaf Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. St Olaf Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of St Olaf Lake?
- St Olaf Lake typically sits around 68°F at the surface in August, from 708 EPA Water Quality Portal field readings (2010–2019). That is a typical value for the month, not a live reading.
How deep is St Olaf Lake?
- St Olaf Lake has a maximum depth of 33 feet. The lake covers 91.2 acres.
What fish are in St Olaf Lake?
- Fish species found in St Olaf Lake include black crappie, bluegill, common carp, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, white crappie, white sucker, yellow bullhead, yellow perch. St Olaf Lake is located in Waseca County, Minnesota.
When does St Olaf Lake thaw?
- St Olaf Lake typically has ice-out around Mar 31. Ice typically forms around Dec 3. The open water season is approximately 247 days.
Are there boat ramps on St Olaf Lake?
- St Olaf Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include St. Olaf Lake. Public access is listed as yes.
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Where this data comes from
98 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA98 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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
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