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LakeQuality
C
Phelps County, Missouri

Little Prairie Lake by Dam

Grade CFair · 4.9 ft clarity

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Eutrophic

Little Prairie Lake by Dam is a 100-acre productive, nutrient-rich eutrophic lake in Phelps County, Missouri. Water quality is graded C based on 3 sampling years through 2024. Water clarity is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Phelps County, Little Prairie Lake by Dam ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-08-14. Grade methodology: LakeGrade methodology.

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Swimming Safety

Generally safe for swimming, moderate water quality

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Water Quality Grade: C, Fair

Murky, only visible to about 4.9 ft. Phosphorus level: 24.5 µg/L. Chlorophyll-a: 6.3 µg/L. Trophic State Index: 51.

MetricValueGrade
Water Clarity (Secchi Depth)4.9 ftD
Phosphorus24.5 µg/LB
Chlorophyll-a (Algae)6.3 µg/LB
Trophic State Index (TSI)51Eutrophic

High nutrients, frequent algae, reduced clarity

Lake Details

CharacteristicValue
Surface Area100 acres
Public AccessYes

Where to stay near Little Prairie Lake by Dam

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Fishing Little Prairie Lake by Dam

Water Quality Trend: Stable

Based on 5 years of monitoring data (2020-2025).

MetricTrendChange/YearYears
Water Clarity Declining-0.303 m/yr4
Phosphorus Stable-0.19 µg/L/yr5
Chlorophyll-a Improving-2.03 µg/L/yr5
See year-by-year chart →

Recreation & Access

1
Boat Landings
Yes
Public Access

Water Temperature

Little Prairie Lake by Dam averages about 82°F at the surface in summer, usually warmest in Jul (about 84°F) and coldest in May (about 71°F). These are typical values by month — not a live reading.

Jan
Feb
Mar
Apr
May
71°
Jun
79°
Jul
84°
Aug
82°
Sep
Oct
Nov
Dec

Typical surface water temperature by month, from 52 field readings (20102024) via the EPA Water Quality Portal. See the full Little Prairie Lake by Dam water temperature breakdown →

Location

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County Ranking

Ranked #1 of 3 lakes in Phelps County

Nearby Lakes in Phelps County

More records, surveys & data sources

Reservoir Info (USACE NID)

Little Prairie Lake by Dam is a man-made reservoir impounded by the William E. Towell Dam (completed 1965), built primarily for recreation on the TRIBUTARY OF BOUBEUSE RIVER; earth-type dam, 48 ft tall and 1,450 ft long.

Surface area
100 ac
Normal storage
1,300 ac-ft
Max storage
2,490 ac-ft
Drainage area
2.41 sq mi
Hazard class
High
Owner
MO DEPT OF CONSERVATION

Source: USACE National Inventory of Dams, NID ID MO30090 · Operator website · Matched by proximity (0.15 km)

EPA Impairment Status

Little Prairie Lake by Dam is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).

Causes of impairment

Mercury

Source: EPA ATTAINS assessment unit MO_7287.00 · Official waterbody report · Matched by proximity (0.48 km)

Lake Size & Watershed

Watershed (drainage) area
3 sq mi
Mean depth (est.)
13.1 ft
Shoreline
2.1 mi
Elevation
1,030 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.

Regulated Pollution Sources Nearby

12 EPA-permitted facilities operate within about 5 miles of Little Prairie Lake by Dam under Clean Water Act (NPDES) discharge permits. 9 facilities have a reported Clean Water Act violation in the past three years.

  • Lakeside Community
    Rolla · 0.4 mi away · NPDES MO0118664
    Recent violation
  • Shady Lane Mhp Wwtf
    Rolla · 0.8 mi away · NPDES MO0092789
    Recent violation
  • Phelps Connections For Seniors Wwtf
    Rolla · 1.2 mi away · NPDES MO0133299
    Recent violation
  • Pcpwsd No. 2 Country Club Terrace Wwtp
    Rolla · 2 mi away · NPDES MO0125059
    Recent violation
  • Pcpwsd No 2 Forest Lakes Subd Wwtp
    Rolla · 2.3 mi away · NPDES MO0125032
    Recent violation
  • Pcpwsd No. 2, Greenlefe Subdivision Wwtf
    Rolla · 2.5 mi away · NPDES MO0125211
    Recent violation

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

Impairment status from EPA ATTAINS 303(d) database

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: 2024-08-14

Monitoring stations: 1

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