Timberline Lakes
St. Francois County, Missouri42 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- Impaired · Nutrients (phosphorus, nitrogen)
- #3 of 4 in the county
Timberline Lakes in St. Francois County, Missouri has a water quality grade of A (Excellent). Water clarity: 14.3 ft visibility. Phosphorus: 5.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Surface area: 42 acres.
- Clarity
- 14.3 ft
- Typical in September
- 77°F
- Area
- 42 acres
- Type
- Oligotrophic
- Phosphorus
- 5.5 µg/L
- Chlorophyll-a
- 1.6 µg/L
- Trend
- ↓ Declining
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Watch Timberline Lakes’s letter
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Timberline Lakes is a 42-acre cold, clear oligotrophic lake in St. Francois County, Missouri. Water quality is graded A based on 2 sampling years through 2024. Overall water quality is declining over recent sampling years. Compared to the 3 other monitored lakes in St. Francois County, Timberline Lakes ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, Missouri DNR, last sampled 2024-09-21. Grade methodology: LakeQuality methodology.
What Timberline Lakes is good for
From access and monitoring records, not editorial picks.
- Clear water14.3 ft of visibility
Swimming Safety
Grade onlyLow algae
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 A is nutrients and algae, not a swimming clearance. Timberline Lakes is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Good clarity, visible to about 14.3 ft. Phosphorus 5.5 µg/L. Chlorophyll-a 1.6 µg/L. TSI 34. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 14.3 ft | Not graded |
| Phosphorus | 5.5 µg/L | Good |
| Chlorophyll-a (Algae) | 1.6 µg/L | Good |
| Trophic State Index (TSI) | 34 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Water Temperature
Timberline Lakes typically sits around 77°F at the surface in September. Summer average is about 82°F. Usually warmest in Jul (about 84°F) and coldest in Apr (about 62°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 52 field readings (2010–2024) via the EPA Water Quality Portal. See the full Timberline Lakes water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 42 acres |
No bathymetric survey has been published for Timberline Lakes, so its depth is not documented here.
Fishing Timberline Lakes
Water Quality Trend: ↓ Declining
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.656 m/yr | 5 |
| Phosphorus | ↓ Declining | +0.45 µg/L/yr | 5 |
| Chlorophyll-a | ↑ Improving | -0.13 µg/L/yr | 5 |
Reservoir Info (USACE NID)
Timberline Lakes is a man-made reservoir impounded by the Lake Timberline Dam (completed 1963), built primarily for recreation on the BEE RUN CREEK; earth-type dam, 79 ft tall and 760 ft long.
- Surface area
- 42 ac
- Normal storage
- 1,083 ac-ft
- Max storage
- 1,464 ac-ft
- Drainage area
- 1.95 sq mi
- Hazard class
- High
- Owner
- LAKE TIMBERLINE BOARD OF TRUST
Source: USACE National Inventory of Dams, NID ID MO30156 · Operator website · Matched by proximity (0.06 km)
EPA Impairment Status
Timberline Lakes 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_7304.00 · Official waterbody report · Matched by proximity (0.47 km)
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Timberline Lakes under Clean Water Act (NPDES) discharge permits. 3 facilities have a reported Clean Water Act violation in the past three years.
- Eagle Estates WwtpBonne Terre · 0.5 mi away · NPDES MO0120260Recent violation
- Stone Park ResortBonne Terre · 1.7 mi away · NPDES MO0137464Recent violation
- Bonne Terre Nw WwtpBonne Terre · 3.9 mi away · NPDES MO0100706Recent violation
- Boopers WwtfValles Mines · 2.4 mi away · NPDES MO0127388
- Bonne Terre Northeast WwtpBonne Terre · 4.8 mi away · NPDES MO0121321
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 #3 of 4 lakes in St. Francois County
Nearby Lakes in St. Francois County
Frequently asked questions about Timberline Lakes
Where is Timberline Lakes?
- Timberline Lakes is a lake in St. Francois County, Missouri. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Timberline Lakes?
- Timberline Lakes in St. Francois County, Missouri has a water quality grade of A (Excellent). Water clarity: 14.3 ft visibility. Phosphorus: 5.5 µg/L. Chlorophyll-a (algae): 1.6 µg/L. Surface area: 42 acres.
Is Timberline Lakes safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Timberline Lakes is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
What is the water temperature of Timberline Lakes?
- Timberline Lakes typically sits around 77°F at the surface in September, from 52 EPA Water Quality Portal field readings (2010–2024). That is a typical value for the month, not a live reading.
Explore Timberline Lakes across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Missouri's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Other Grade A Lakes in Missouri
Oligotrophic Lakes in Missouri
Where this data comes from
117 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
UMC117 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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)