Jefferson County, Missouri · Water Quality Report Card
Lake Tishomingo
Lake Tishomingo in Jefferson County, Missouri has a water quality grade of C (Fair). Water clarity: 5.4 ft visibility. Phosphorus: 23.5 µg/L. Chlorophyll-a (algae): 7.1 µg/L.
- Clarity
- 5.4 ft
- Mean depth
- ~16 ft est.
- Type
- Eutrophic
- Trend
- ↑ Improving
Lake Tishomingo is a productive, nutrient-rich eutrophic lake in Jefferson County, Missouri with an estimated average depth of about 16 feet. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Compared to the 3 other monitored lakes in Jefferson County, Lake Tishomingo ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-13. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C (Fair)
Murky, only visible to about 5.4 ft. Phosphorus level: 23.5 µg/L. Chlorophyll-a: 7.1 µg/L. Trophic State Index: 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.4 ft | |
| Phosphorus | 23.5 µg/L | Fair |
| Chlorophyll-a (Algae) | 7.1 µg/L | Fair |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~16 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Missouri has not published bathymetry for Lake Tishomingo.
Where to stay near Lake Tishomingo
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Fishing Lake Tishomingo
Water Quality Trend: ↑ Improving
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.54 m/yr | 2 |
| Phosphorus | ↑ Improving | -6.85 µg/L/yr | 3 |
| Chlorophyll-a | ↑ Improving | -3.65 µg/L/yr | 3 |
Location
County Ranking
Ranked #2 of 4 lakes in Jefferson County
Cleaner Lakes Within 30 Miles
Lake Tishomingo holds Grade C. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Jefferson County
Explore Lake Tishomingo across LakeGrade
Planning a trip around Gateway Arch?
Lake Tishomingo is about 31 miles from Gateway Arch National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Gateway Arch →More Missouri Lake Rankings
Other Grade C Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Where this data comes from
48 measurements from 1 monitoring station, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC48 samples · 2022–2024
Analytical methods
- Depth, Secchi disk in meters
- 4500 P E ~ Phosphorus in Water by Colorimetry- Ascorbic Acid Method
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
Grade thresholds come from the U.S. EPA National Lakes Assessment 2022 Technical Support Document (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated.
Data Sources
Water quality data from the EPA Water Quality Portal
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion
Most recent sample: 2024-08-13
Monitoring stations: 1