Gaystock Lake
Gaystock Lake in Carver County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 236 µg/L. Chlorophyll-a (algae): 78.3 µg/L.
- Clarity
- 0.7 ft
- Typical in August
- 77°F
- Public access
- No
Next lake in Carver County
Why Gaystock 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 Gaystock 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.
Gaystock Lake is a lake in Carver County, Minnesota. Limited fish-species data available. No public access — the lake is private or restricted.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2022-10-05. 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 Gaystock Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Very murky, less than 0.7 ft of visibility. Phosphorus level: 236 µg/L. Chlorophyll-a: 78.3 µg/L. Trophic State Index: 80.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 0.7 ft | Not graded |
| Phosphorus | 236 µg/L | Not graded |
| Chlorophyll-a (Algae) | 78.3 µg/L | Not graded |
| Trophic State Index (TSI) | 80 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Gaystock Lake
Compare lakeside cabins, hotels, and vacation rentals near Gaystock Lake in Carver 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 Gaystock Lake
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Water Temperature
Gaystock Lake typically sits around 77°F at the surface in August. Summer average is about 71°F. Usually warmest in Aug (about 77°F) and coldest in Oct (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 20 field readings (2022–2022) via the EPA Water Quality Portal. See the full Gaystock Lake water temperature breakdown →
Fishing Gaystock Lake
EPA Impairment Status
Gaystock 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 MN10-0031-00 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Gaystock Lake under Clean Water Act (NPDES) discharge permits.
- CarverCarver · 2.7 mi away · NPDES MN0053457
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 Gaystock Lake
Gaystock Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Carver County
Frequently asked questions about Gaystock Lake
What is the water quality grade for Gaystock Lake?
- Gaystock Lake in Carver County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 0.7 ft visibility. Phosphorus: 236 µg/L. Chlorophyll-a (algae): 78.3 µg/L.
Is Gaystock Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Gaystock Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Algae concentration (chlorophyll-a) is 78.3 µg/L. Always check local health department advisories before swimming.
What is the water temperature of Gaystock Lake?
- Gaystock Lake typically sits around 77°F at the surface in August, from 20 EPA Water Quality Portal field readings (2022–2022). That is a typical value for the month, not a live reading.
Explore Gaystock Lake across LakeGrade
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Where this data comes from
8 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA8 samples · 2022
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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)