Nilan Reservoir
Nilan Reservoir in Lewis and Clark County, Montana is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 521 acres.
- Area
- 521 acres
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Why Nilan 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 Nilan 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 Montana DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Nilan Reservoir is a 521-acre lake in Lewis and Clark County, Montana.
Source: EPA Water Quality Portal sampling records, Montana DEQ, 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 Nilan 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 Nilan Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Nilan Reservoir in Lewis and Clark County, Montana — 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.
Top-rated places to stay near Nilan Reservoir
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 521 acres |
No bathymetric survey has been published for Nilan Reservoir, so its depth is not documented here.
Fishing Nilan Reservoir
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Frequently asked questions about Nilan Reservoir
Where is Nilan Reservoir?
- Nilan Reservoir is a lake in Lewis and Clark County, Montana. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Nilan Reservoir?
- Nilan Reservoir in Lewis and Clark County, Montana is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 521 acres.
Is Nilan Reservoir safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Nilan Reservoir is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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Where this data comes from
Measurements for Nilan Reservoir come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.