Rock Lake
Platte County, Wyoming37 acresView mapDirections
Not enough samples to grade — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. No letter yet. Here is what we do have.
- 26 ft max depth
- Limited data
Rock Lake in Platte County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.8 ft visibility. Phosphorus: 12.4 µg/L. Surface area: 37 acres.
- Clarity
- 3.8 ft
- Max depth
- ~26 ft est.
- Area
- 37 acres
- Phosphorus
- 12.4 µg/L
- Trend
- → Stable
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Watch Rock Lake’s letter
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Why Rock 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 Rock Lake, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. Sampling here has recorded water clarity and phosphorus, but not algae (chlorophyll-a).
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 Wyoming DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Rock Lake is a 37-acre lake in Platte County, Wyoming with an estimated average depth of about 26 feet. Water clarity is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2015-09-03. 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 Rock Lake
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 3.8 ft. Phosphorus 12.4 µg/L. TSI 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.8 ft | Not graded |
| Phosphorus | 12.4 µg/L | Not graded |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~26 ft est. |
| Average Depth | ~6 ft est. |
| Surface Area | 37 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Wyoming has not published bathymetry for Rock Lake.
Lake Size & Watershed
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.
Fishing Rock Lake
Water Quality Trend: → Stable
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.183 m/yr | 2 |
| Phosphorus | ↓ Declining | +2.5 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Rock Lake is a man-made reservoir impounded by the Rock Lake (completed 1930), built primarily for irrigation on the North Wheatland Creek; earth-type dam, 15 ft tall and 660 ft long.
- Surface area
- 37 ac
- Normal storage
- 250 ac-ft
- Max storage
- 334 ac-ft
- Drainage area
- 0 sq mi
- Hazard class
- Low
- Owner
- WHEATLAND IRRIGATION DISTRICT
Source: USACE National Inventory of Dams, NID ID WY00033 · Operator website
Graded lakes near Rock Lake
Rock Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Platte County
Frequently asked questions about Rock Lake
Where is Rock Lake?
- Rock Lake is a lake in Platte County, Wyoming. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Rock Lake?
- Rock Lake in Platte County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.8 ft visibility. Phosphorus: 12.4 µg/L. Surface area: 37 acres.
Is Rock Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
How deep is Rock Lake?
- No published bathymetric survey covers Rock Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 26 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 37 acres.
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Where this data comes from
6 measurements from 1 monitoring station, 2015. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- State of Wyoming Department of Environmental Quality Watershed Program
WYDEQ_WATERSHED6 samples · 2015
Analytical methods
- Secchi
- Total Phosphorus After Block Digestion
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
Lake size & watershed from HydroLAKES (HydroSHEDS)