Macon County, Missouri · 39.75°N · Water Quality Report Card
Long Branch Lake
Long Branch Lake in Macon County, Missouri is not rated for water quality — its monitoring record does not meet the evidence bar. Phosphorus: 36 µg/L.
- Mean depth
- ~49 ft est.
- Type
- Eutrophic
- Trend
- ↑ Improving
Long Branch Lake is a productive, nutrient-rich eutrophic lake in Macon County, Missouri with an estimated average depth of about 49 feet. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2020-08-24. Grade methodology: LakeGrade methodology.
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Swimming Safety
Not rated for swimming — there is not enough monitoring data to judge this lake
Water Quality Grade: Not rated
No clarity data. Phosphorus level: 36 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 36 µg/L | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~49 ft est. |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Missouri has not published bathymetry for Long Branch Lake.
Where to stay near Long Branch Lake
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Fishing Long Branch Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.008 m/yr | 5 |
| Phosphorus | → Stable | +0.18 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.36 µg/L/yr | 5 |
Location
Nearby Lakes in Macon County
Explore Long Branch Lake across LakeGrade
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Other Lakes in Missouri
Eutrophic Lakes in Missouri
More records, surveys & data sources
EPA Impairment Status
Long Branch Lake is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MO_7168.00 · Official waterbody report · Matched by proximity (1.7 km)
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
1 measurement from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Missouri Dept. of Natural Resources
MDNR1 sample · 2020
Analytical methods
- Nitrogen and Phosphorus, Total, Whole-water, Alkaline Persulfate Digest
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
Impairment status from EPA ATTAINS 303(d) database
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: 2020-08-24
Monitoring stations: 1