Lake Ottawa
Lake Ottawa in Iron County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 19.5 ft visibility. Surface area: 531.4 acres.
- Clarity
- 19.5 ft
- Area
- 531 acres
- Trend
- → Stable
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Why Lake Ottawa 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 Lake Ottawa, 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, but not phosphorus and 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 EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Lake Ottawa is a 531-acre lake in Iron County, Michigan. Water clarity is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-08-28. Grade methodology: LakeQuality methodology.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
Water quality measurements for Lake Ottawa
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 19.5 ft down. Trophic State Index: 34.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 19.5 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Lake Ottawa
Compare lakeside cabins, hotels, and vacation rentals near Lake Ottawa in Iron County, Michigan — 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 Lake Ottawa
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Planning a whole trip? See where to stay at Michigan’s top lakes →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 531 acres |
No bathymetric survey has been published for Lake Ottawa, so its depth is not documented here.
Fishing Lake Ottawa
Water Quality Trend: → Stable
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.03 m/yr | 6 |
| Phosphorus | ↓ Declining | +0.57 µg/L/yr | 6 |
Graded lakes near Lake Ottawa
Lake Ottawa has no grade, but these lakes within a short drive do.
Nearby Lakes in Iron County
Frequently asked questions about Lake Ottawa
Where is Lake Ottawa?
- Lake Ottawa is a lake in Iron County, Michigan. LakeQuality has not rated this lake (UNRATED) — there is not enough recent sampling to assign a letter.
What is the water quality grade for Lake Ottawa?
- Lake Ottawa in Iron County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 19.5 ft visibility. Surface area: 531.4 acres.
Is Lake Ottawa safe to swim in?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Lake Ottawa 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
29 measurements from 1 monitoring station, 2017–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS29 samples · 2017–2022
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.