Castle Rock Dam Lake
Hettinger County, North Dakota14 acresView mapDirections
ND DEQ publishes the water-quality measurements for Castle Rock Dam Lake. Here is what has been measured.
- Eutrophic
- Limited data
Castle Rock Dam Lake in Hettinger County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. Water clarity: 3.8 ft visibility. Phosphorus: 148 µg/L. Chlorophyll-a (algae): 24.3 µg/L. Surface area: 14.2 acres.
Castle Rock Dam Lake is a 14-acre productive, nutrient-rich eutrophic lake in Hettinger County, North Dakota. 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. Methodology: how these readings are compared.
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 Castle Rock 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 Castle Rock Dam Lake
These are the measurements ND DEQ publishes for Castle Rock 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 3.8 ft. Phosphorus 148 µg/L. Chlorophyll-a 24.3 µg/L. TSI 65.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.8ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 148µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 24.3µg/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. | 65 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Castle Rock Dam Lake
Answers come straight from the public measurements and survey records on this page.
Water Temperature
Castle Rock Dam Lake typically sits around 49°F at the surface in October. 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.
Column height runs from this lake’s coldest month (49°F) to its warmest (63°F).
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
Surface area
14 acres
No bathymetric survey has been published for Castle Rock Dam Lake, so its depth is not documented here.
Stays via Stay22
Stays near Castle Rock Dam Lake
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 readings cover nutrients and algae, not lodging. Cabins and rentals around Castle Rock Dam Lake are listed below.
Top-rated places to stay near Castle Rock Dam Lake
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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
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. Its water-quality measurements are published by ND DEQ and shown on this page as reported.
What is the water quality of Castle Rock Dam Lake?
- Castle Rock Dam Lake in Hettinger County, North Dakota has water-quality measurements published by ND DEQ, shown here as reported. 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?
- Nutrient and algae readings are 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 49°F at the surface in October, from 12 EPA Water Quality Portal field readings (2023–2023). That is a typical value for the month, not a live reading.
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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)
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
Depth, fish, and access data from North Dakota Game & Fish