Dion Lake
Rolette County, North DakotaView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- 24 ft max depth
- Public access
- Limited data
Dion Lake in Rolette County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.5 ft visibility.
- Clarity
- 8.5 ft
- Typical in September
- 51°F
- Max depth
- ~24 ft est.
- Public access
- Yes
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Stays near Dion Lake
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Watch Dion Lake’s letter
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Why Dion Lake has no grade
Dion Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Dion Lake is Not Rated — not an F. Its 8.5-foot median from 8 readings collected 2025 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. 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.
Dion Lake is a lake in Rolette County, North Dakota with an estimated average depth of about 24 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 2025-10-01. Grade methodology: LakeQuality methodology.
What Dion 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 Dion Lake
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 8.5 ft. TSI 46.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 46 | Mesotrophic |
Moderate nutrients, good water quality
Water Temperature
Dion Lake typically sits around 51°F at the surface in September. Summer average is about 65°F. Usually warmest in Jun (about 68°F) and coldest in Sep (about 51°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 17 field readings (2016–2025) via the EPA Water Quality Portal. See the full Dion Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~24 ft est. |
| Average Depth | ~12 ft est. |
| 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 Dion 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
- Dion LakePublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Dion Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
Source: USGS Nonindigenous Aquatic Species (NAS) Database. Hover a chip to see scientific name, ecological context, status, and first-observed year.
Graded lakes near Dion Lake
Dion Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Rolette County
Frequently asked questions about Dion Lake
Where is Dion Lake?
- Dion Lake is a lake in Rolette 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 Dion Lake?
- Dion Lake in Rolette County, North Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 8.5 ft visibility.
Is Dion Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Dion Lake?
- Dion Lake typically sits around 51°F at the surface in September, from 17 EPA Water Quality Portal field readings (2016–2025). That is a typical value for the month, not a live reading.
How deep is Dion Lake?
- No published bathymetric survey covers Dion Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 24 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Are there boat ramps on Dion Lake?
- Dion Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Dion Lake. Public access is listed as yes.
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Where this data comes from
8 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX8 samples · 2025
Analytical methods
- Phosphorus by Colorimetry
- 447.0 ~ EPA; Chlorophyll a and b in phytoplankton by HPLC/UV
- 4500 NO3 E ~ Nitrate in Water- Cadmium Reduction
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