Big Johnstone Lake
Big Johnstone Lake in Kenai Peninsula County, Alaska is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 3558 acres.
- Area
- 3,558 acres
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Why Big Johnstone 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 Big Johnstone Lake, 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 your state environmental agency and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Big Johnstone Lake is a 3,558-acre lake in Kenai Peninsula County, Alaska.
Source: EPA Water Quality Portal sampling records, your state environmental agency, 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 Big Johnstone Lake
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 Big Johnstone Lake
Compare lakeside cabins, hotels, and vacation rentals near Big Johnstone Lake in Kenai Peninsula County, Alaska — 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 Big Johnstone Lake
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Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 3,558 acres |
No bathymetric survey has been published for Big Johnstone Lake, so its depth is not documented here.
Fishing Big Johnstone Lake
Nearby Lakes in Kenai Peninsula County
Frequently asked questions about Big Johnstone Lake
Where is Big Johnstone Lake?
- Big Johnstone Lake is a lake in Kenai Peninsula County, Alaska. LakeQuality has not rated this lake (UNRATED) — no water-quality sampling on record for this lake.
What is the water quality grade for Big Johnstone Lake?
- Big Johnstone Lake in Kenai Peninsula County, Alaska is not rated for water quality — its monitoring record does not meet the evidence bar. Surface area: 3558 acres.
Is Big Johnstone Lake safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Big Johnstone Lake 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 Big Johnstone Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.