Lake Ottawa
Iron County, Michigan531 acresView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Limited data
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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Stays 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.
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Watch Lake Ottawa’s letter
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Why Lake Ottawa has no grade
Lake Ottawa has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Lake Ottawa is Not Rated — not an F. Its 19.5-foot median from 29 readings collected 2017–2022 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. 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.
What Lake Ottawa is good for
From access and monitoring records, not editorial picks.
- Clear water19.5 ft of visibility
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
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. TSI 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. The letter is not a swimming clearance.
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) — 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 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?
- The letter is not a swimming clearance. Check local advisories before you swim.
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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.