Horsethief Reservoir
Horsethief Reservoir in Valley County, Idaho is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 247 acres.
- Area
- 247 acres
- Public access
- Yes
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Why Horsethief Reservoir 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 Horsethief Reservoir, no water-quality sampling on record for this lake.
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 IDEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Horsethief Reservoir is a 247-acre lake in Valley County, Idaho. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, IDEQ, last sampled recent years. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedElevated nutrients
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Horsethief Reservoir
These readings exist but are not enough for an A–F grade — see why.
No clarity data. Trophic State Index: undefined.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) |
Where to stay near Horsethief Reservoir
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 247 acres |
| Public Access | Yes |
No bathymetric survey has been published for Horsethief Reservoir, so its depth is not documented here.
Recreation & Access
- Horsethief ReservoirPublic
- Horsethief ReservoirPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Horsethief Reservoir
Nearby Lakes in Valley County
Frequently asked questions about Horsethief Reservoir
Where is Horsethief Reservoir?
- Horsethief Reservoir is a lake in Valley County, Idaho. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Horsethief Reservoir?
- Horsethief Reservoir in Valley County, Idaho is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 247 acres.
Is Horsethief Reservoir safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Horsethief Reservoir is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
Are there boat ramps on Horsethief Reservoir?
- Horsethief Reservoir has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Horsethief Reservoir, Horsethief Reservoir. Public access is listed as yes.
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Where this data comes from
Measurements for Horsethief Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.
Other records on this page
Named boat-access points from the USGS National Boat Ramps inventory