Borah Lake is a highly nutrient-loaded hypereutrophic lake in Richland County, Illinois. Water quality is graded F based on 2 sampling years through 2022. Limited fish-species data available. Public access is available with 1 public boat landing. Compared to the 2 other monitored lakes in Richland County, Borah Lake ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Illinois DNR, last sampled 2022-10-13. Grade methodology: LakeGrade methodology.
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Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 2.2 ft of visibility. Phosphorus level: 131 µg/L. Trophic State Index: 70.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 2.2 ft | F |
| Phosphorus | 131 µg/L | F |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 70 | Hypereutrophic |
Very high nutrients, dense algae, poor clarity
Where to stay near Borah Lake
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Fishing Borah Lake
Recreation & Access
Water Temperature
Borah Lake averages about 77°F at the surface in summer, usually warmest in Aug (about 79°F) and coldest in Apr (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 209 field readings (2014–2022) via the EPA Water Quality Portal. See the full Borah Lake water temperature breakdown →
Location
County Ranking
Ranked #3 of 3 lakes in Richland County
Cleaner Lakes Within 30 Miles
Borah Lake holds Grade F. 3 nearby lakes hold higher grades.
- COlney East Fork LakeRichland County · 1.3 mi · Two grade letters higher (F → C)
- DVernor LakeRichland County · 2.1 mi · Higher grade (F → D)
- DNewton LakeJasper County · 15.3 mi · Higher grade (F → D)
Nearby Lakes in Richland County
Explore Borah Lake across LakeGrade
Species activity outlook by water temperature and season
Where to stay at Illinois's top lakes, each with its grade
Very high nutrients, dense algae, poor clarity
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Other Grade F Lakes in Illinois
Hypereutrophic Lakes in Illinois
More records, surveys & data sources
Reservoir Info (USACE NID)
Borah Lake is a man-made reservoir impounded by the M. D. Borah Lake Dam (completed 1953), built primarily for recreation on the TRIB FOX RIVER; earth-type dam, 36 ft tall and 960 ft long.
- Normal storage
- 2,060 ac-ft
- Max storage
- 4,720 ac-ft
- Hazard class
- High
- Owner
- CITY OF OLNEY
All listed purposes: Recreation;Water Supply.
Source: USACE National Inventory of Dams, NID ID IL00331 · Operator website · Matched by proximity (0.87 km)
EPA Impairment Status
Borah Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IL_RCB · Official waterbody report · Matched by proximity (0.17 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Borah Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- West Liberty - Dundas Sanitary District StpDundas · 4.1 mi away · NPDES IL0077879Recent 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: 2022-10-13
Monitoring stations: 3