Agate Lake
Agate Lake in Crow Wing County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11 ft visibility. Maximum depth: 25 ft. Surface area: 187.03 acres.
- Clarity
- 11 ft
- Typical in August
- 76°F
- Max depth
- 25 ft
- Area
- 187 acres
- Trend
- ↓ Declining
- Public access
- Yes
- Ice-out
- Apr 16
Next lake in Crow Wing County
Why Agate 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 Agate 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, but not 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.
Agate Lake is a 187-acre lake in Crow Wing County, Minnesota with a maximum depth of 25 feet. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-28. 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 Agate Lake
These readings exist but do not meet the evidence bar for an A–F grade — see why.
Good clarity, visible to about 11 ft. Trophic State Index: 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Agate Lake
Compare lakeside cabins, hotels, and vacation rentals near Agate Lake in Crow Wing 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 Agate Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Agate Lake typically sits around 76°F at the surface in August. Summer average is about 74°F. Usually warmest in Jul (about 76°F) and coldest in May (about 63°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 54 field readings (2016–2025) via the EPA Water Quality Portal. See the full Agate Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 25 ft |
| Surface Area | 187 acres |
| Shoreline Length | 2.6 mi |
| Littoral Zone | 42% |
| Public Access | Yes |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Recreation & Access
- Black LakePublic
- Serpent Lake (East)Public
Fishing Agate Lake
DNR Fisheries Survey Summary
2 surveys on file from MN DNR Fisheries. Most recent: 1989-06-19 (Standard Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 49.10 | 0.18 lb |
| Yellow Perch | 25.54 | 0.13 lb |
| Pumpkinseed | 4.75 | 0.24 lb |
| Rock Bass | 3.67 | 0.29 lb |
| Northern Pike | 2.86 | 5.31 lb |
| Black Crappie | 2.58 | 0.25 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
From the 1989-06-19 survey
The fish population levels in numbers and average size of fish as determined from the range of median values for appropriate types of gear are indicated in the following table. High population levels are indicated by catch rates above the third quartile and low population levels by catch rates below the first…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Agate Lake. 1 report on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — AgateFisheries Lake Survey · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.114 m/yr | 5 |
Ice Season
Historical ice data from Minnesota DNR (17 observations).
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 1992-04-04 (1992) | 2008-04-30 (2008) |
| Ice-In | 2014-11-15 (2014) | 2007-11-22 (2007) |
Most recent ice-out: 2015-04-07
EPA Impairment Status
Agate 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 MN18-0090-00 · Official waterbody report · Matched by proximity (2.08 km)
Graded lakes near Agate Lake
Agate Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Crow Wing County
Frequently asked questions about Agate Lake
What is the water quality grade for Agate Lake?
- Agate Lake in Crow Wing County, Minnesota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11 ft visibility. Maximum depth: 25 ft. Surface area: 187.03 acres.
Is Agate Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Agate Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
What is the water temperature of Agate Lake?
- Agate Lake typically sits around 76°F at the surface in August, from 54 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Agate Lake?
- Agate Lake has a maximum depth of 25 feet. The lake covers 187.03 acres.
When does Agate Lake thaw?
- Agate Lake typically has ice-out around Apr 16.
Are there boat ramps on Agate Lake?
- Agate Lake has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Black Lake, Serpent Lake (East). Public access is listed as yes.
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Where this data comes from
42 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA42 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
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
Ice data from Minnesota DNR Climate