Inez Lake
Missoula County, MontanaView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #4 of 40 in the county
Inez Lake in Missoula County, Montana has a water quality grade of A (Excellent). Phosphorus: 7.1 µg/L. Chlorophyll-a (algae): 1.8 µg/L.
- Type
- Oligotrophic
- Phosphorus
- 7.1 µg/L
- Chlorophyll-a
- 1.8 µg/L
- Trend
- → Stable
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Watch Inez Lake’s letter
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Inez Lake is a cold, clear oligotrophic lake in Missoula County, Montana. Water quality is graded A based on 3 sampling years through 2025. Phosphorus level is declining over recent sampling years. Compared to the 39 other monitored lakes in Missoula County, Inez Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Montana DEQ, last sampled 2025-09-12. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
No clarity data. Phosphorus 7.1 µg/L. Chlorophyll-a 1.8 µg/L. TSI 34. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 7.1 µg/L | Good |
| Chlorophyll-a (Algae) | 1.8 µg/L | Good |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Inez Lake
Water Quality Trend: → Stable
Based on 12 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.234 m/yr | 8 |
| Phosphorus | ↓ Declining | +1.54 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.9 µg/L/yr | 2 |
County Ranking
Ranked #4 of 40 lakes in Missoula County
Nearby Lakes in Missoula County
Frequently asked questions about Inez Lake
Where is Inez Lake?
- Inez Lake is a lake in Missoula County, Montana. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Inez Lake?
- Inez Lake in Missoula County, Montana has a water quality grade of A (Excellent). Phosphorus: 7.1 µg/L. Chlorophyll-a (algae): 1.8 µg/L.
Is Inez Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Inez Lake across LakeQuality
6.6 mi away · 90 ft
Species activity outlook by water temperature and season
Where to stay at Montana's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
Montana's cleanest and most-polluted lakes, ranked
More Montana Lake Rankings
Other Grade A Lakes in Montana
Oligotrophic Lakes in Montana
Where this data comes from
25 measurements from 1 monitoring station, 2023–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Montana Volunteer Water Quality Monitoring
MTVOLWQM_WQX25 samples · 2023–2025
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 4500 N C ~ Persufate Method for Total Nitrogen
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.