Castle Rock Dam Lake
Hettinger County, North Dakota14 acresView mapDirections
Nutrients and algae run above the regional average.
- Eutrophic
- #2 of 3 in the county
- Limited data
Castle Rock Dam Lake in Hettinger County, North Dakota has a water quality grade of D (Nutrient-rich). Water clarity: 3.8 ft visibility. Phosphorus: 148 µg/L. Chlorophyll-a (algae): 24.3 µg/L. Surface area: 14.2 acres.
- Clarity
- 3.8 ft
- Typical in August
- 63°F
- Area
- 14 acres
- Type
- Eutrophic
- Phosphorus
- 148 µg/L
- Chlorophyll-a
- 24.3 µg/L
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Compare lakeside cabins, hotels, and vacation rentals near Castle Rock Dam Lake in Hettinger 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 grade measures nutrients and algae, not lodging — cabins and rentals around Castle Rock Dam Lake are listed below.
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Castle Rock Dam Lake is a 14-acre productive, nutrient-rich eutrophic lake in Hettinger County, North Dakota. Water quality is graded D based on 1 sampling years through 2023. Compared to the 2 other monitored lakes in Hettinger County, Castle Rock Dam Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, NDDEQ, last sampled 2023-10-10. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 3.8 ft. Phosphorus 148 µg/L. Chlorophyll-a 24.3 µg/L. TSI 65. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.8 ft | Not graded |
| Phosphorus | 148 µg/L | Not graded |
| Chlorophyll-a (Algae) | 24.3 µg/L | Not graded |
| Trophic State Index (TSI) | 65 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Castle Rock Dam Lake typically sits around 63°F at the surface in August. Summer average is about 63°F. Usually warmest in Aug (about 63°F) and coldest in Oct (about 49°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 12 field readings (2023–2023) via the EPA Water Quality Portal. See the full Castle Rock Dam Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 14 acres |
No bathymetric survey has been published for Castle Rock Dam Lake, so its depth is not documented here.
Fishing Castle Rock Dam Lake
Reservoir Info (USACE NID)
Castle Rock Dam Lake is a man-made reservoir impounded by the Castle Rock Dam (completed 1969), built primarily for recreation on the Cannonball River-TR; earth-type dam, 18 ft tall and 818 ft long.
- Surface area
- 14.2 ac
- Normal storage
- 75.1 ac-ft
- Max storage
- 184 ac-ft
- Drainage area
- 2.66 sq mi
- Hazard class
- Low
- Owner
- Louise & Larry Roemmich
Source: USACE National Inventory of Dams, NID ID ND00261 · Operator website
County Ranking
Ranked #2 of 3 lakes in Hettinger County
Nearby Lakes in Hettinger County
Frequently asked questions about Castle Rock Dam Lake
Where is Castle Rock Dam Lake?
- Castle Rock Dam Lake is a lake in Hettinger County, North Dakota. LakeQuality grades it D for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Castle Rock Dam Lake?
- Castle Rock Dam Lake in Hettinger County, North Dakota has a water quality grade of D (Nutrient-rich). Water clarity: 3.8 ft visibility. Phosphorus: 148 µg/L. Chlorophyll-a (algae): 24.3 µg/L. Surface area: 14.2 acres.
Is Castle Rock Dam Lake safe to swim in?
- The D is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Castle Rock Dam Lake?
- Castle Rock Dam Lake typically sits around 63°F at the surface in August, from 12 EPA Water Quality Portal field readings (2023–2023). That is a typical value for the month, not a live reading.
Explore Castle Rock Dam Lake across LakeQuality
Species activity outlook by water temperature and season
Where to stay at North Dakota's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
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Other Grade D Lakes in North Dakota
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Where this data comes from
20 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_WQX20 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)
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
Depth, fish, and access data from North Dakota Game & Fish