Tolna Dam Lake
Nelson County, North Dakota166 acresView mapDirections
ND DEQ publishes the water-quality measurements for Tolna Dam Lake. Here is what has been measured.
- 65 ft max depth
- Public access
- Limited data
Tolna Dam Lake in Nelson County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 4.9 ft visibility. Surface area: 166.3 acres.
Tolna Dam Lake is a 166-acre lake in Nelson County, North Dakota with an estimated average depth of about 65 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 2025-10-13. Methodology: how these readings are compared.
What Tolna Dam Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Tolna Dam Lake is safe to swim in today is a call for the North Dakota Department of Environmental Quality and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Tolna Dam Lake
These are the measurements ND DEQ publishes for Tolna Dam 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 4.9 ft. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 4.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Tolna Dam Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Tolna Dam Lake typically sits around 55°F at the surface in October. Summer average is about 67°F. Usually warmest in Aug (about 71°F) and coldest in Oct (about 55°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (55°F) to its warmest (71°F).
Typical surface water temperature by month, from 12 field readings (2010–2025) via the EPA Water Quality Portal. See the full Tolna Dam Lake water temperature breakdown →
Lake Details
Max depth
~65 ft est.
Surface area
166 acres
Public access
Yes
Listed by ND DEQ
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 Tolna Dam Lake.
Lake Size & Watershed
Watershed (drainage) area
53 sq mi
HydroLAKES / HydroSHEDS
Shoreline
3.3 mi
HydroLAKES / HydroSHEDS
Elevation
1,391 ft
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
- Tolna DamPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays near Tolna Dam Lake
Compare lakeside cabins, hotels, and vacation rentals near Tolna Dam Lake in Nelson County, North Dakota — 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 Tolna Dam Lake
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Fishing Tolna Dam Lake
Reservoir Info (USACE NID)
Tolna Dam Lake is a man-made reservoir impounded by the Tolna Dam 1 (completed 1936), built primarily for recreation on the Tolna Coulee; earth-type dam, 36 ft tall and 520 ft long.
- Surface area
- 166.3 ac
- Normal storage
- 2,027 ac-ft
- Max storage
- 3,080 ac-ft
- Drainage area
- 40 sq mi
- Hazard class
- Significant
- Owner
- Nelson County WRB
Source: USACE National Inventory of Dams, NID ID ND00027 · Operator website · Matched by proximity (0.27 km)
Nearby Lakes in Nelson County
Frequently asked questions about Tolna Dam Lake
Where is Tolna Dam Lake?
- Tolna Dam Lake is a lake in Nelson County, North Dakota. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Tolna Dam Lake?
- Tolna Dam Lake in Nelson County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 4.9 ft visibility. Surface area: 166.3 acres.
Is Tolna Dam Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Tolna Dam Lake?
- Tolna Dam Lake typically sits around 55°F at the surface in October, from 12 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Tolna Dam Lake?
- No published bathymetric survey covers Tolna Dam Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 65 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 166.3 acres.
Are there boat ramps on Tolna Dam Lake?
- Tolna Dam Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Tolna Dam. Public access is listed as yes.
Can I fish at Tolna Dam Lake?
- Tolna Dam Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by North Dakota's fish and wildlife agency, so check its current regulations before you go.
Explore Tolna Dam Lake across LakeQuality
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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)
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
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