Canyon Lake
Pennington County, South Dakota29 acresView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- Limited data
Canyon Lake in Pennington County, South Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Surface area: 29 acres.
- Typical in August
- 62°F
- Area
- 29 acres
- Phosphorus
- 20 µg/L
- Chlorophyll-a
- 1.3 µg/L
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Stays near Canyon Lake
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Watch Canyon Lake’s letter
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Why Canyon Lake has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Canyon Lake, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded phosphorus and algae (chlorophyll-a), but not water clarity.
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by SD DANR and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Canyon Lake is a 29-acre lake in Pennington County, South Dakota.
Source: EPA Water Quality Portal sampling records, SD DANR, last sampled 2021-06-09. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Canyon Lake
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Phosphorus 20 µg/L. Chlorophyll-a 1.3 µg/L. TSI 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 20 µg/L | Not graded |
| Chlorophyll-a (Algae) | 1.3 µg/L | Not graded |
| Trophic State Index (TSI) | 40 | Mesotrophic |
Moderate nutrients, good water quality
Water Temperature
Canyon Lake typically sits around 62°F at the surface in August. Summer average is about 61°F. Usually warmest in Aug (about 62°F) and coldest in Mar (about 42°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 47 field readings (2018–2021) via the EPA Water Quality Portal. See the full Canyon Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 29 acres |
No bathymetric survey has been published for Canyon Lake, so its depth is not documented here.
Fishing Canyon Lake
Reservoir Info (USACE NID)
Canyon Lake is a man-made reservoir impounded by the Canyon Lake Dam (completed 1976), built primarily for irrigation on the RAPID CREEK; earth-type dam, 31 ft tall and 1,325 ft long.
- Surface area
- 29 ac
- Normal storage
- 140 ac-ft
- Max storage
- 610 ac-ft
- Drainage area
- 66 sq mi
- Hazard class
- High
- Owner
- CITY OF RAPID CITY
All listed purposes: Irrigation;Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID SD02137 · Operator website
Regulated Pollution Sources Nearby
7 EPA-permitted facilities operate within about 5 miles of Canyon Lake under Clean Water Act (NPDES) discharge permits. 4 facilities have a reported Clean Water Act violation in the past three years.
- Sd Gfp - Cleghorn Fish HatcheryRapid City · 0.5 mi away · NPDES SD0000060Recent violation
- Gcc DacotahRapid City · 2.3 mi away · NPDES SD0000027Recent violation
- Pete Lien & Sons, IncRapid City · 4.1 mi away · NPDES SD0000094Recent violation
- Black Hills Corp LctfRapid City · 4.5 mi away · NPDES SD0027871Recent violation
- Sd Army National GuardRapid City · 1.9 mi away · NPDES SD0027332
- Black Hills Power, IncRapid City · 2.4 mi away · NPDES SD0000141
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Nearby Lakes in Pennington County
Frequently asked questions about Canyon Lake
Where is Canyon Lake?
- Canyon Lake is a lake in Pennington County, South 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 Canyon Lake?
- Canyon Lake in Pennington County, South Dakota is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 1.3 µg/L. Surface area: 29 acres.
Is Canyon Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Canyon Lake?
- Canyon Lake typically sits around 62°F at the surface in August, from 47 EPA Water Quality Portal field readings (2018–2021). That is a typical value for the month, not a live reading.
Explore Canyon Lake across LakeQuality
Planning a trip around Wind Cave?
Canyon Lake is about 34 miles from Wind Cave National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Wind Cave →More South Dakota Lake Rankings
Other Lakes in South Dakota
Where this data comes from
11 measurements from 1 monitoring station, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS South Dakota Water Science Center
USGS-SD11 samples · 2021
Analytical methods
- Phosphorus, wu, microKJ ASF, H+
- Plant pigments, sonication & 445
- YSI EXO turbidity sensor, FNU
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)