Mud Lake
Bear Lake County, IdahoView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Eutrophic
- #5 of 5 in the county
- Limited data
Mud Lake in Bear Lake County, Idaho has a water quality grade of C (Fair). Phosphorus: 46 µg/L.
- Type
- Eutrophic
- Phosphorus
- 46 µg/L
- Trend
- ↑ Improving
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Watch Mud Lake’s letter
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Mud Lake is a productive, nutrient-rich eutrophic lake in Bear Lake County, Idaho. Water quality is graded C based on 1 sampling years through 2023. Overall water quality is improving over recent sampling years. Compared to the 4 other monitored lakes in Bear Lake County, Mud Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, IDEQ, last sampled 2023-11-14. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
No clarity data. Phosphorus 46 µg/L. TSI 59. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 46 µg/L | Fair |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 59 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Fishing Mud Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | ↑ Improving | -1.37 µg/L/yr | 2 |
County Ranking
Ranked #5 of 5 lakes in Bear Lake County
Nearby Lakes in Bear Lake County
Frequently asked questions about Mud Lake
Where is Mud Lake?
- Mud Lake is a lake in Bear Lake County, Idaho. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mud Lake?
- Mud Lake in Bear Lake County, Idaho has a water quality grade of C (Fair). Phosphorus: 46 µg/L.
Is Mud Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Mud Lake across LakeQuality
3 thermal springs within 24.6 mi, nearest Bear Lake Hot Springs
Species activity outlook by water temperature and season
Where to stay at Idaho's top lakes, each with its grade
High nutrients, frequent algae, reduced clarity
Idaho's cleanest and most-polluted lakes, ranked
More Idaho Lake Rankings
Other Grade C Lakes in Idaho
Eutrophic Lakes in Idaho
Where this data comes from
100 measurements from 1 monitoring station, 2019–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- USGS Utah Water Science Center
USGS-UT100 samples · 2019–2023
Analytical methods
- P, wu, WCA, persulfate CF color
- YSI Environmental, sensor 6136
- YSI model 6026-4000, FNU
- YSI EXO turbidity sensor, FNU
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.