Mark Twain Lake Indian Creek Arm
Ralls County, MissouriView mapDirections
Nutrients and algae sit mid-range for this region.
- Eutrophic
- #1 of 3 in the county
- Public access
Mark Twain Lake Indian Creek Arm in Ralls County, Missouri has a water quality grade of C (Fair). Water clarity: 3.8 ft visibility. Phosphorus: 31.5 µg/L. Chlorophyll-a (algae): 14.2 µg/L.
- Clarity
- 3.8 ft
- Typical in September
- 75°F
- Type
- Eutrophic
- Phosphorus
- 31.5 µg/L
- Chlorophyll-a
- 14.2 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Watch Mark Twain Lake Indian Creek Arm’s letter
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Mark Twain Lake Indian Creek Arm is a productive, nutrient-rich eutrophic lake in Ralls County, Missouri. Water quality is graded C based on 2 sampling years through 2024. Overall water quality is improving over recent sampling years. Limited fish-species data available. Public access is available with 3 public boat landings. Compared to the 2 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: LakeQuality methodology.
What Mark Twain Lake Indian Creek Arm is good for
From access and monitoring records, not editorial picks.
- Boat launch3 documented ramps
Swimming Safety
Grade onlyModerate
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)
Murky, only visible to about 3.8 ft. Phosphorus 31.5 µg/L. Chlorophyll-a 14.2 µg/L. TSI 56. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.8 ft | Not graded |
| Phosphorus | 31.5 µg/L | Good |
| Chlorophyll-a (Algae) | 14.2 µg/L | Fair |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Water Temperature
Mark Twain Lake Indian Creek Arm typically sits around 75°F at the surface in September. Summer average is about 78°F. 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 →
Recreation & Access
- Route J Reservoir (Monroe City)Public
- John F. Spalding Recreation AreaPublic
- Route NPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
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 |
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.
County Ranking
Ranked #1 of 3 lakes in Ralls County
Nearby Lakes in Ralls County
Frequently asked questions about Mark Twain Lake Indian Creek Arm
Where is Mark Twain Lake Indian Creek Arm?
- Mark Twain Lake Indian Creek Arm is a lake in Ralls County, Missouri. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Mark Twain Lake Indian Creek Arm?
- Mark Twain Lake Indian Creek Arm in Ralls County, Missouri has a water quality grade of C (Fair). Water clarity: 3.8 ft visibility. Phosphorus: 31.5 µg/L. Chlorophyll-a (algae): 14.2 µg/L.
Is Mark Twain Lake Indian Creek Arm safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Mark Twain Lake Indian Creek Arm?
- Mark Twain Lake Indian Creek Arm typically sits around 75°F at the surface in September, from 98 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Are there boat ramps on Mark Twain Lake Indian Creek Arm?
- Mark Twain Lake Indian Creek Arm has 3 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Route J Reservoir (Monroe City), John F. Spalding Recreation Area, Route N. Public access is listed as yes.
Explore Mark Twain Lake Indian Creek Arm across LakeQuality
More Missouri Lake Rankings
Other Grade C Lakes in Missouri
Eutrophic Lakes in Missouri
Where this data comes from
110 measurements from 1 monitoring station, 2020–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Univ. of Missouri, Columbia
UMC110 samples · 2020–2024
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 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.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory