Orwell Lake
Orwell Lake in Otter Tail County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.1 ft visibility. Phosphorus: 54 µg/L. Chlorophyll-a (algae): 9.7 µg/L. Maximum depth: 25 ft. Surface area: 607.58 acres.
- Clarity
- 4.1 ft
- Typical in August
- 77°F
- Max depth
- 25 ft
- Area
- 608 acres
- Trend
- ↓ Declining
- Public access
- Yes
Next lake in Otter Tail County
Why Orwell 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 Orwell 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, 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.
Orwell Lake is a 608-acre lake in Otter Tail County, Minnesota with a maximum depth of 25 feet. Overall water quality is declining over recent sampling years. The lake supports 17 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-06-28. Grade methodology: LakeGrade methodology.
Watch Orwell Lake water quality
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Orwell Lake Water Quality Report Card (2026)
A printable one-page report card for Orwell Lake: grade, clarity, phosphorus, algae, multi-year trend, depth, and fish — with sources.
Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Orwell Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Murky, only visible to about 4.1 ft. Phosphorus level: 54 µg/L. Chlorophyll-a: 9.7 µg/L. Trophic State Index: 57.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.1 ft | Not graded |
| Phosphorus | 54 µg/L | Not graded |
| Chlorophyll-a (Algae) | 9.7 µg/L | Not graded |
| Trophic State Index (TSI) | 57 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Orwell Lake
Compare lakeside cabins, hotels, and vacation rentals near Orwell Lake in Otter Tail 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 Orwell Lake
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Current Conditions
USGS snapshot Jul 6, 2026, 5:00 AM from gauge 05045950 (Orwell Lake at Orwell Dam Near Fergus Falls, MN). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
Water Temperature
Orwell Lake typically sits around 77°F at the surface in August. Summer average is about 76°F. Usually warmest in Aug (about 77°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 63 field readings (2016–2022) via the EPA Water Quality Portal. See the full Orwell Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 25 ft |
| Surface Area | 608 acres |
| Shoreline Length | 11.7 mi |
| Littoral Zone | 100% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Dayton Hollow ReservoirPublic
- Orwell ReservoirPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Orwell 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
7 surveys on file from MN DNR Fisheries. Most recent: 2024-05-13 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Black Crappie | 26.47 | 0.39 lb |
| Black Bullhead | 6.15 | 0.39 lb |
| Common Carp | 5.18 | 2.39 lb |
| SLR | 4.87 | 1.1 lb |
| Channel Catfish | 4.21 | 1.87 lb |
| Walleye | 3.49 | 1.29 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 Crappie
Black Bullhead
Common Carp
SLR
From the 2024-05-13 survey
Orwell Reservoir is a United States Army Corps of Engineers flood control impoundment. It is located approximately 8 miles southwest of Fergus Falls, MN in Otter Tail County. Construction of the dam on the Otter Tail River was completed in 1952, and the reservoir encompasses 782-acres at normal pool. Because the main…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Orwell Lake. 4 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — OrwellFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Orwell (1033)Aquatic Plant Report · MN DNR LakeFinder
- —Fish Stocking History — OrwellFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — OrwellPublic Water Access Sites · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.4 m/yr | 2 |
Reservoir Info (USACE NID)
Orwell Lake is a man-made reservoir impounded by the Orwell Dam (completed 1953), built primarily for flood risk reduction on the OTTER TAIL RIVER; earth-type dam, 60 ft tall and 1,355 ft long.
- Surface area
- 805 ac
- Normal storage
- 8,050 ac-ft
- Max storage
- 20,600 ac-ft
- Drainage area
- 1,820 sq mi
- Hazard class
- High
- Owner
- USACE - St. Paul District
All listed purposes: Flood Risk Reduction;Other;Fish and Wildlife Pond;Recreation.
Source: USACE National Inventory of Dams, NID ID MN00574 · Operator website
EPA Impairment Status
Orwell 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 MN56-0945-00 · Official waterbody report
Graded lakes near Orwell Lake
Orwell Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Otter Tail County
Frequently asked questions about Orwell Lake
What is the water quality grade for Orwell Lake?
- Orwell Lake in Otter Tail County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.1 ft visibility. Phosphorus: 54 µg/L. Chlorophyll-a (algae): 9.7 µg/L. Maximum depth: 25 ft. Surface area: 607.58 acres.
Is Orwell Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Orwell Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 9.7 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Orwell Lake?
- Orwell Lake typically sits around 77°F at the surface in August, from 63 EPA Water Quality Portal field readings (2016–2022). That is a typical value for the month, not a live reading.
How deep is Orwell Lake?
- Orwell Lake has a maximum depth of 25 feet. The lake covers 607.58 acres.
What fish are in Orwell Lake?
- Fish species found in Orwell Lake include bigmouth buffalo, black bullhead, black crappie, bluegill, bowfin (dogfish), channel catfish, common carp, golden redhorse, greater redhorse, northern pike, rock bass, shorthead redhorse, smallmouth bass, walleye, white sucker, yellow bullhead, yellow perch. Orwell Lake is located in Otter Tail County, Minnesota.
What is the water level at Orwell Lake?
- The USGS snapshot on this page for Orwell Lake is 64.07 ft of gage height, recorded Jul 6, 2026, 5:00 AM at gauge 05045950. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Are there boat ramps on Orwell Lake?
- Orwell Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Dayton Hollow Reservoir, Orwell Reservoir. Public access is listed as yes.
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Where this data comes from
10 measurements from 1 monitoring station, 2021–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA10 samples · 2021–2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2120 B ~ Color in Water by Visual Comparison
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