Green Lake
McIntosh County, North Dakota906 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- 29 ft max depth
- Public access
- Limited data
Green Lake in McIntosh County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 906 acres.
- Typical in September
- 55°F
- Max depth
- ~29 ft est.
- Area
- 906 acres
- Public access
- Yes
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Watch Green Lake’s letter
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Why Green Lake has no grade
We grade a lake only when the monitoring record supports a letter: 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 Green Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
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 NDDEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Green Lake is a 906-acre lake in McIntosh County, North Dakota with an estimated average depth of about 29 feet. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2024-04-29. Grade methodology: LakeQuality methodology.
What Green Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Green Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples |
Water Temperature
Green Lake typically sits around 55°F at the surface in September. Summer average is about 60°F. Usually warmest in Jul (about 60°F) and coldest in May (about 45°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 9 field readings (2019–2019) via the EPA Water Quality Portal. See the full Green Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~29 ft est. |
| Average Depth | ~6 ft est. |
| Surface Area | 906 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Dakota has not published bathymetry for Green Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Green LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Green Lake
Reservoir Info (USACE NID)
Green Lake is a man-made reservoir impounded by the Green Lake Outlet Control (completed 1973), built primarily for recreation on the Pudwill Lake-TR; earth-type dam, 7 ft tall and 856 ft long.
- Surface area
- 906 ac
- Normal storage
- 5,436 ac-ft
- Max storage
- 8,622 ac-ft
- Drainage area
- 51 sq mi
- Hazard class
- Low
- Owner
- McIntosh County WRB
Source: USACE National Inventory of Dams, NID ID ND00373 · Operator website · Matched by proximity (0.85 km)
Graded lakes near Green Lake
Green Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in McIntosh County
Frequently asked questions about Green Lake
Where is Green Lake?
- Green Lake is a lake in McIntosh County, North Dakota. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Green Lake?
- Green Lake in McIntosh County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 906 acres.
Is Green Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Green Lake?
- Green Lake typically sits around 55°F at the surface in September, from 9 EPA Water Quality Portal field readings (2019–2019). That is a typical value for the month, not a live reading.
How deep is Green Lake?
- No published bathymetric survey covers Green Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 29 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 906 acres.
Are there boat ramps on Green Lake?
- Green Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Green Lake. Public access is listed as yes.
Explore Green Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
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Other Lakes in North Dakota
Where this data comes from
1 measurement from 1 monitoring station, 2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX1 sample · 2024
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Depth, fish, and access data from North Dakota Game & Fish
Named boat-access points from the USGS National Boat Ramps inventory