Froelich Dam Lake
Sioux County, North Dakota175 acresView mapDirections
ND DEQ publishes the water-quality measurements for Froelich Dam Lake. Here is what has been measured.
- Hypereutrophic
- 20 ft max depth
- Public access
- Limited data
Froelich Dam Lake in Sioux County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 311.5 µg/L. Chlorophyll-a (algae): 37.5 µg/L. Surface area: 175 acres.
Froelich Dam Lake is a 175-acre highly nutrient-loaded hypereutrophic lake in Sioux County, North Dakota with an estimated average depth of about 20 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 2023-10-20. Methodology: how these readings are compared.
Froelich Dam Lake covers about 180 acres in Sioux County. It has one public boat landing. Vrbo is where to look for cabins and lake homes around Froelich Dam Lake, and Booking.com and Expedia search hotels near the lake for your dates.
What Froelich Dam Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming conditions
Readings onlyLimited data
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Froelich 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 Froelich Dam Lake
These are the measurements ND DEQ publishes for Froelich 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 3.9 ft. Phosphorus 311.5 µg/L. Chlorophyll-a 37.5 µg/L. TSI 70.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.9ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 312µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 37.5µg/L | Measured, not scored 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. | 70 | Hypereutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Very high nutrients, dense algae, poor clarity
Ask about Froelich Dam Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Froelich Dam Lake typically sits around 48°F at the surface in October. Summer average is about 69°F. Usually warmest in Jul (about 73°F) and coldest in Oct (about 48°F). These are typical values by month — not a live reading.
Column height runs from this lake’s coldest month (48°F) to its warmest (73°F).
Typical surface water temperature by month, from 67 field readings (2017–2023) via the EPA Water Quality Portal. See the full Froelich Dam Lake water temperature breakdown →
Lake Details
Max depth
~20 ft est.
Surface area
175 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 Froelich Dam Lake.
Lake Size & Watershed
Watershed (drainage) area
5 sq mi
HydroLAKES / HydroSHEDS
Shoreline
3.4 mi
HydroLAKES / HydroSHEDS
Elevation
1,965 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
- Froelich 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 Froelich Dam Lake
Compare lakeside cabins, hotels, and vacation rentals near Froelich Dam Lake in Sioux 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. The water-quality readings cover nutrients and algae, not lodging. Cabins and rentals around Froelich Dam Lake are listed below.
Top-rated places to stay near Froelich Dam Lake
Prices for Oct 23–25, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip? Cabins and lodging at Froelich Dam Lake → · more North Dakota lake trips
Follow Froelich Dam Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Fishing Froelich Dam Lake
Reservoir Info (USACE NID)
Froelich Dam Lake is a man-made reservoir impounded by the Froelich Dam (completed 1962), built primarily for recreation on the Porcupine Creek-TR; earth-type dam, 46 ft tall and 821 ft long.
- Surface area
- 175 ac
- Normal storage
- 2,271.3 ac-ft
- Max storage
- 4,212.9 ac-ft
- Drainage area
- 68.3 sq mi
- Hazard class
- Low
- Owner
- ND Game & Fish
All listed purposes: Recreation;Fire Protection, Stock, Or Small Fish Pond.
Source: USACE National Inventory of Dams, NID ID ND00025 · Operator website
Nearby Lakes in Sioux County
Frequently asked questions about Froelich Dam Lake
Where is Froelich Dam Lake?
- Froelich Dam Lake is a lake in Sioux 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 Froelich Dam Lake?
- Froelich Dam Lake in Sioux County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 3.9 ft visibility. Phosphorus: 311.5 µg/L. Chlorophyll-a (algae): 37.5 µg/L. Surface area: 175 acres.
Is Froelich 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 Froelich Dam Lake?
- Froelich Dam Lake typically sits around 48°F at the surface in October, from 67 EPA Water Quality Portal field readings (2017–2023). That is a typical value for the month, not a live reading.
How deep is Froelich Dam Lake?
- No published bathymetric survey covers Froelich Dam Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 20 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 175 acres.
Are there boat ramps on Froelich Dam Lake?
- Froelich Dam Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Froelich Dam. Public access is listed as yes.
Can I fish at Froelich Dam Lake?
- Froelich 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 Froelich Dam Lake across LakeQuality
More lakes in North Dakota
Other Lakes in North Dakota
Hypereutrophic Lakes in North Dakota
Where this data comes from
19 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North Dakota Department Of Environmental Quality
21NDHDWQ_WQX19 samples · 2023
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