Lower Prior Lake
Lower Prior Lake in Scott County, Minnesota has a water quality grade of C (Fair). Water clarity: 10 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 4.8 µg/L. Maximum depth: 60 ft. Surface area: 956.16 acres.
- Clarity
- 10 ft
- Typical in August
- 71°F
- Max depth
- 60 ft
- Area
- 956 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 4
- Open water
- 241 days
Next lake in Scott County
Free interactive depth-contour map of Lower Prior Lake, reaching a maximum surveyed depth of 50 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Minnesota DNR.
Lower Prior Lake is a 956-acre mesotrophic lake in Scott County, Minnesota with a maximum depth of 60 feet. Water quality is graded C based on 3 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 15 documented fish species including black crappie, bluegill, and brown bullhead. Public access is available with 1 public boat landing. Compared to the 20 other monitored lakes in Scott County, Lower Prior Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-10-13. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyModerate
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.
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Good clarity, visible to about 10 ft. Phosphorus level: 27 µg/L. Chlorophyll-a: 4.8 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10 ft | Not graded |
| Phosphorus | 27 µg/L | Fair |
| Chlorophyll-a (Algae) | 4.8 µg/L | Good |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lower Prior Lake
Compare lakeside cabins, hotels, and vacation rentals near Lower Prior Lake in Scott 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 Lower Prior Lake
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Water Temperature
Lower Prior Lake typically sits around 71°F at the surface in August. Summer average is about 69°F. Usually warmest in Aug (about 71°F) and coldest in Apr (about 46°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 1,637 field readings (2010–2025) via the EPA Water Quality Portal. See the full Lower Prior Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 60 ft |
| Surface Area | 956 acres |
| Shoreline Length | 14.7 mi |
| Littoral Zone | 39% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Sand PointPublic
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Lower Prior 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
17 surveys on file from MN DNR Fisheries. Most recent: 2025-09-09 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 24.77 | 0.17 lb |
| SFS | 19.32 | — |
| Bluntnose Minnow | 12.85 | — |
| Largemouth Bass | 7.39 | 0.54 lb |
| GOS | 6.29 | 0.17 lb |
| Yellow Bass | 3.40 | 0.82 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
GOS
Yellow Bass
From the 2025-09-09 survey
Minnesota DNR Fisheries IBI program staff conducted an assessment of lakeshore habitat on Lower Prior Lake on September 9th 2025, following the Score the Shore survey protocols. The assessment consisted of 119 survey sites evenly spaced 200 meters around the lake. Assessments were made in three habitat zones:…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Lower Prior Lake. 3 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Lower PriorFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — Lower PriorFish Stocking History · MN DNR LakeFinder
- —Public Water Access Sites — Lower PriorPublic 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 | → Stable | -0.02 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.89 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +0.4 µg/L/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (62 observations).
Estimated open water season: 241 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-03 (2024) | 2018-05-02 (2018) |
| Ice-In | 1986-11-15 (1986) | 2001-12-26 (2001) |
Most recent ice-out: 2025-03-25
Reservoir Info (USACE NID)
Lower Prior Lake is a man-made reservoir impounded by the Prior Lake on the Minnesota River-TR; gravity-type dam, 12 ft tall and 8 ft long.
- Surface area
- 1,056 ac
- Normal storage
- 1,760 ac-ft
- Drainage area
- 35 sq mi
- Hazard class
- Low
- Owner
- MNDNR
Source: USACE National Inventory of Dams, NID ID MN01328 · Operator website
EPA Impairment Status
Lower Prior 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 MN70-0026-00 · Official waterbody report
County Ranking
Ranked #4 of 21 lakes in Scott County
Nearby Lakes in Scott County
Frequently asked questions about Lower Prior Lake
What is the water quality grade for Lower Prior Lake?
- Lower Prior Lake in Scott County, Minnesota has a water quality grade of C (Fair). Water clarity: 10 ft visibility. Phosphorus: 27 µg/L. Chlorophyll-a (algae): 4.8 µg/L. Maximum depth: 60 ft. Surface area: 956.16 acres.
Is Lower Prior Lake safe to swim in?
- Generally safe for swimming, moderate water quality. Lower Prior Lake has a water quality grade of C (Fair). Algae concentration (chlorophyll-a) is 4.8 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Lower Prior Lake?
- Lower Prior Lake typically sits around 71°F at the surface in August, from 1,637 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Lower Prior Lake?
- Lower Prior Lake has a maximum depth of 60 feet. The lake covers 956.16 acres.
What fish are in Lower Prior Lake?
- Fish species found in Lower Prior Lake include black crappie, bluegill, brown bullhead, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, walleye, white bass, white crappie, white sucker, yellow bullhead, yellow perch. Lower Prior Lake is located in Scott County, Minnesota.
When does Lower Prior Lake thaw?
- Lower Prior Lake typically has ice-out around Apr 4. Ice typically forms around Dec 1. The open water season is approximately 241 days.
Are there boat ramps on Lower Prior Lake?
- Lower Prior Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Sand Point. Public access is listed as yes.
Explore Lower Prior Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Scott County
Species activity outlook by water temperature and season
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Where this data comes from
471 measurements from 3 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
MNPCA471 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 4500 N C ~ Persufate Method for Total Nitrogen
- Turbidity, Nephelometric Method
Monitoring station identifiers (3)
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