Half Moon Lake
Hennepin County, Minnesota33 acresView mapDirections
Minnesota PCA publishes the water-quality measurements for Half Moon Lake. Here is what has been measured.
- Eutrophic
- Impaired · Mercury
- 25 ft max depth
Half Moon Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.2 ft visibility. Phosphorus: 109.1 µg/L. Chlorophyll-a (algae): 35.6 µg/L. Maximum depth: 25 ft. Surface area: 33.03 acres.
Minnesota DNR's Standard Survey on July 6, 2009 caught 1.50 walleye per gill net at Half Moon Lake. DNR survey details →
Half Moon Lake is a 33-acre productive, nutrient-rich eutrophic lake in Hennepin County, Minnesota with a maximum depth of 25 feet. Overall water quality is improving over recent sampling years. The lake supports 12 documented fish species including black bullhead, black crappie, and bluegill. No public access — the lake is private or restricted. Compared to the 80 other monitored lakes in Hennepin County, Half Moon Lake ranks #72 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2024-10-07. Methodology: how these readings are compared.
What Half Moon Lake is good for
From access and monitoring records, not editorial picks.
- Fishing12 species recorded
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. Half Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Whether Half Moon Lake 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 Half Moon Lake
These are the measurements Minnesota PCA publishes for Half Moon Lake, 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 4.2 ft. Phosphorus 109.1 µg/L. Chlorophyll-a 35.6 µg/L. TSI 65.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.2ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 109µg/L | Poor GoodFairPoor |
| Chlorophyll-a (algae) | 35.6µg/L | Poor GoodFairPoor |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 65 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Half Moon Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Half Moon Lake typically sits around 55°F at the surface in October. Summer average is about 59°F. Usually warmest in Jul (about 60°F) and coldest in Jan (about 36°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (36°F) to its warmest (60°F).
Typical surface water temperature by month, from 973 field readings (2010–2024) via the EPA Water Quality Portal. See the full Half Moon Lake water temperature breakdown →
Minnesota DNR's Standard Survey on July 6, 2009 caught 1.50 walleye per gill net at Half Moon Lake.
A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Half Moon Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
DNR Fisheries Survey Summary
5 surveys on file from MN DNR Fisheries. Most recent: 2009-07-06 (Standard Survey).
5 surveys on file · most recent 2009-07-06 (Standard Survey)
17 years old| Species | Catch rate (CPUE) | Size | Avg weight |
|---|---|---|---|
| Black Bullhead | 24.04 | 9–11 in 2009-07-06 | 0.48 lb |
| Black Crappie | 20.36 | 5–8 in 2009-07-06 | 0.19 lb |
| Bluegill | 12.80 | 4–8 in 2009-07-06 | 0.16 lb |
| Northern Pike | 6.61 | 23–34 in 2009-07-06 | 2.35 lb |
| Yellow Bullhead | 3.85 | 9–10 in 2009-07-06 | 0.48 lb |
| Brown Bullhead | 3.48 | 7–15 in 2009-07-06 | 0.68 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.
Black Bullhead
Black Crappie
Bluegill
Northern Pike
From the 2009-07-06 survey
Half Moon is a 30-acre lake located in the Baker Park Reserve operated by the Three Rivers Park District. There is a parking lot, carry-in canoe access, and fishing pier on the west side of the lake. No gas boat motors are permitted. The fishery includes bluegill, black crappie, yellow perch, largemouth bass, and…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Half Moon Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Half MoonFisheries Lake Survey · MN DNR LakeFinder
Lake Details
Max depth
25 ft
Surface area
33 acres
Shoreline
1.2 mi
Littoral zone
54%
Share shallower than 15 ft
Public access
No
Listed by Minnesota PCA
Stays via Stay22
Stays near Half Moon Lake
Compare lakeside cabins, hotels, and vacation rentals near Half Moon Lake in Hennepin 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 readings cover nutrients and algae, not lodging. Cabins and rentals around Half Moon Lake are listed below.
Top-rated places to stay near Half Moon Lake
Prices for Oct 9–11, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Minnesota’s top lakes →
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Fish Species
Click a species to see every lake where it is documented.
Fishing Half Moon Lake
Water Quality Trend: Improving
Based on 6 years of monitoring (2020–2025).
Water clarity
Stable6 years
Phosphorus
Improving-12.22 µg/L/yr4 years
Chlorophyll-a
Improving-5.03 µg/L/yr4 years
EPA Impairment Status
Half Moon Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
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 MN27-0152-00 · Official waterbody report
Nearby Lakes in Hennepin County
Frequently asked questions about Half Moon Lake
Where is Half Moon Lake?
- Half Moon Lake is a lake in Hennepin County, Minnesota. Its water-quality measurements are published by Minnesota PCA and shown on this page as reported.
What is the water quality of Half Moon Lake?
- Half Moon Lake in Hennepin County, Minnesota has water-quality measurements published by Minnesota PCA, shown here as reported. Water clarity: 4.2 ft visibility. Phosphorus: 109.1 µg/L. Chlorophyll-a (algae): 35.6 µg/L. Maximum depth: 25 ft. Surface area: 33.03 acres.
Is Half Moon Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Half Moon Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury, nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Half Moon Lake?
- Half Moon Lake typically sits around 55°F at the surface in October, from 973 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
How deep is Half Moon Lake?
- Half Moon Lake has a maximum depth of 25 feet. The lake covers 33.03 acres.
What fish are in Half Moon Lake?
- Fish species found in Half Moon Lake include black bullhead, black crappie, bluegill, bowfin (dogfish), brown bullhead, hybrid sunfish, largemouth bass, northern pike, walleye, white sucker, yellow bullhead, yellow perch. Half Moon Lake is located in Hennepin County, Minnesota.
What did the DNR fisheries survey find at Half Moon Lake?
- Minnesota DNR's Standard Survey on July 6, 2009 caught 1.50 walleye per gill net at Half Moon Lake. A DNR fisheries survey reports fish abundance and catch rates, not water quality. LakeQuality shows Half Moon Lake’s water-quality measurements separately, and the water-quality trend over 6 years of monitoring is improving. Catch rate is not a swim clearance and is not a weekly bite report.
Can I fish at Half Moon Lake?
- Public access to Half Moon Lake is listed as no on the lake record, so confirm before you make the trip. 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.
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Where this data comes from
287 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA287 samples · 2020–2024
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
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
Lake details from Minnesota DNR LakeFinder