Mark Twain Lake Indian Creek Arm is a productive, nutrient-rich eutrophic lake in Ralls County, Missouri. Water quality is graded C based on 3 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 2 public boat landings. Compared to the 3 other monitored lakes in Ralls County, Mark Twain Lake Indian Creek Arm ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-31. 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 3.8 ft. Phosphorus level: 31.5 µg/L. Chlorophyll-a: 14.2 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.8 ft | D |
| Phosphorus | 31.5 µg/L | C |
| Chlorophyll-a (Algae) | 14.2 µg/L | C |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Mark Twain Lake Indian Creek Arm
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Fishing Mark Twain Lake Indian Creek Arm
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.14 m/yr | 5 |
| Phosphorus | ↑ Improving | -6.45 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -1.69 µg/L/yr | 5 |
Recreation & Access
Water Temperature
Mark Twain Lake Indian Creek Arm averages about 78°F at the surface in summer, usually warmest in Jul (about 80°F) and coldest in Apr (about 56°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 98 field readings (2010–2024) via the EPA Water Quality Portal. See the full Mark Twain Lake Indian Creek Arm water temperature breakdown →
Location
County Ranking
Ranked #1 of 4 lakes in Ralls County
Nearby Lakes in Ralls County
Explore Mark Twain Lake Indian Creek Arm across LakeGrade
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 is a modeled estimate.
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Mark Twain Lake Indian Creek Arm under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Mark Twain Landing ResortMonroe City · 2.5 mi away · NPDES MO0103675Recent violation
- Usace Indian Creek WwtfMonroe City · 2.8 mi away · NPDES MO0127272
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2024-08-31
Monitoring stations: 1