Pool of Lake St Croix
Washington County, Minnesota8,393 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Pool of Lake St Croix. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- Eurasian watermilfoil
- 78 ft max depth
- Public access
Pool of Lake St Croix in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 39.2 µg/L. Maximum depth: 78 ft. Surface area: 8393.04 acres.
Minnesota DNR's Standard Survey on July 7, 2009 caught 1.12 walleye per gill net at Pool of Lake St Croix. DNR survey details →
Pool of Lake St Croix is a 8,393-acre productive, nutrient-rich eutrophic lake in Washington County, Minnesota with a maximum depth of 78 feet. Overall water quality is declining over recent sampling years. The lake supports 36 documented fish species including bigmouth buffalo, black bullhead, and black crappie. Public access is available with 5 public boat landings. Compared to the 74 other monitored lakes in Washington County, Pool of Lake St Croix ranks #30 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-29. Methodology: how these readings are compared.
What Pool of Lake St Croix is good for
From access and monitoring records, not editorial picks.
- Boat launch5 documented ramps
- Fishing36 species recorded
- Deep water78 ft surveyed max depth
- Big water8,393 acres
Swimming conditions
Readings onlyRecreation use not supported
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Pool of Lake St Croix is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pFAS, pCBs. Check local advisories before you swim.
Whether Pool of Lake St Croix is safe to swim in today is a call for the Minnesota Pollution Control Agency and the Minnesota DNR and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Pool of Lake St Croix
These are the measurements Minnesota PCA publishes for Pool of Lake St Croix, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 4.3 ft. Phosphorus 39.2 µg/L. TSI 57.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 39.2µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 57 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Pool of Lake St Croix
Answers come straight from the public measurements and survey records on this page.
Minnesota DNR's Standard Survey on July 7, 2009 caught 1.12 walleye per gill net at Pool of Lake St Croix.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Pool of Lake St Croix’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
18 surveys on file from MN DNR Fisheries. Most recent: 2024-10-21 (Standard Survey).
18 surveys on file · most recent 2024-10-21 (Standard Survey)
| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Smallmouth Bass | 4.97 | 5–19 in 2024-10-21 | 0.9 lb |
| Common Carp | 4.04 | 19–31 in 2024-04-15 | 4.74 lb |
| Freshwater Drum | 2.99 | 5–13 in 2024-10-21 | 0.61 lb |
CPUE = catch per unit effort, fish caught per net per set in a standardised survey. It measures abundance, not size, and 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
Common Carp
Freshwater Drum
From the 2024-10-21 survey
A gill net survey was conducted on Lake St. Croix in 2024 and sampled 970 fish represented by 28 different species and one hybrid. Over 51% of the fish sampled were considered game fish species (those species which have defined creel limits). Composition of the top five game fish species sampled were 29.8% Yellow…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Pool of Lake St Croix. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — St. CroixFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — St. CroixFish Stocking History · MN DNR LakeFinder
Lake Details
Max depth
78 ft
Surface area
8,393 acres
Shoreline
124.5 mi
Public access
Yes
Listed by Minnesota PCA
Recreation & Access
- Twin SpringsPublic
- Bayport - Lakeside ParkPublic
- St. Croix River BoomsitePublic
- Wolf MarinaSemi-private
- Ole Sawmill MarinaSemi-private
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Pool of Lake St Croix
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Fish Species
Click a species to see every lake where it is documented.
Fishing Pool of Lake St Croix
- → Pool of Lake St Croix fishing: DNR survey catch rates, species & stocking
- → Pool of Lake St Croix fishing forecast & best times (species outlook + 14-day solunar calendar)
- → Pool of Lake St Croix fishing regulations (limits, seasons, special rules)
- → Is it safe to eat fish from Pool of Lake St Croix? (mercury & PFAS guide)
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: Worsening
Based on 5 years of monitoring (2020–2024).
Water clarity
Stable5 years
Phosphorus
Worsening+6.49 µg/L/yr5 years
EPA Impairment Status
Pool of Lake St Croix is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN82-0001-00 · Official waterbody report
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Pool of Lake St Croix under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 1 facility has a reported Clean Water Act violation in the past three years.
- Xcel Energy - Allen S King Generating PlantOak Park Heights · 1 mi away · NPDES MN0000825MajorRecent violation
- Andersen CorpBayport · 0.6 mi away · NPDES MN0001724
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.
Nearby Lakes in Washington County
Frequently asked questions about Pool of Lake St Croix
Where is Pool of Lake St Croix?
- Pool of Lake St Croix is a lake in Washington County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Pool of Lake St Croix?
- Pool of Lake St Croix in Washington County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.3 ft visibility. Phosphorus: 39.2 µg/L. Maximum depth: 78 ft. Surface area: 8393.04 acres.
Is Pool of Lake St Croix safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Pool of Lake St Croix is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, nutrients (phosphorus, nitrogen), pFAS, pCBs. Check local advisories before you swim.
How deep is Pool of Lake St Croix?
- Pool of Lake St Croix has a maximum depth of 78 feet. The lake covers 8393.04 acres.
What fish are in Pool of Lake St Croix?
- Fish species found in Pool of Lake St Croix include bigmouth buffalo, black bullhead, black crappie, bluegill, channel catfish, common carp, flathead catfish, freshwater drum, gizzard shad, golden redhorse, highfin carpsucker, hybrid sunfish, lake sturgeon, largemouth bass, longnose gar, mooneye, muskellunge, northern pike, paddlefish, quillback, river carpsucker, river redhorse, rock bass, sauger, shorthead redhorse, shortnose gar, silver redhorse, smallmouth bass, smallmouth buffalo, spotted sucker, walleye, walleye/sauger, white bass, white crappie, white sucker, yellow perch. Pool of Lake St Croix is located in Washington County, Minnesota.
What did the DNR fisheries survey find at Pool of Lake St Croix?
- Minnesota DNR's Standard Survey on July 7, 2009 caught 1.12 walleye per gill net at Pool of Lake St Croix. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Pool of Lake St Croix’s water-quality measurements separately, and the water-quality trend over 5 years of monitoring is declining. Catch rate is not a swim clearance and is not a weekly bite report.
Are there boat ramps on Pool of Lake St Croix?
- Pool of Lake St Croix has 5 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Twin Springs, Bayport - Lakeside Park, St. Croix River Boomsite, Wolf Marina, among others. Public access is listed as yes.
Can I fish at Pool of Lake St Croix?
- Pool of Lake St Croix has 5 documented boat landings in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Minnesota's fish and wildlife agency, so check its current regulations before you go.
Explore Pool of Lake St Croix across LakeQuality
Depth, room, public access, and the state wake-sport rules
4 mi away · 45 ft
Fish species and the cleanest lakes across Minnesota
Fish species and best lakes in Washington County
Species activity outlook by water temperature and season
Where to stay at Minnesota's top lakes, each with its readings
Lakes in the St. Croix Watershed, ranked by water quality
Minnesota's cleanest lakes, ranked on agency measurements
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Where this data comes from
68 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- National Park Service Water Resources Division
11NPSWRD_WQX68 samples · 2020–2024
Analytical methods
- Secchi Disk
- Alkaline Persulfate Digestion for Total N and P in Water
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from 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 details from Minnesota DNR LakeFinder
Named boat-access points from the USGS National Boat Ramps inventory