Timnath Reservoir
Larimer County, ColoradoView mapDirections
Not enough samples to grade — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). No letter yet. Here is what we do have.
- 20 ft max depth
- Limited data
Timnath Reservoir in Larimer County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.6 ft visibility. Phosphorus: 16.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
- Clarity
- 5.6 ft
- Max depth
- ~20 ft est.
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Watch Timnath Reservoir’s letter
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Why Timnath Reservoir has no grade
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Timnath Reservoir, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. Everything below that has been measured is still reported on this page.
Sampling is run by CDPHE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Timnath Reservoir is a lake in Larimer County, Colorado with an estimated average depth of about 20 feet.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2021-07-14. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Timnath Reservoir
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 5.6 ft. Phosphorus 16.5 µg/L. Chlorophyll-a 10.7 µg/L. TSI 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5.6 ft | Not graded |
| Phosphorus | 16.5 µg/L | Not graded |
| Chlorophyll-a (Algae) | 10.7 µg/L | Not graded |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~20 ft est. |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for Timnath Reservoir.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Fishing Timnath Reservoir
Graded lakes near Timnath Reservoir
Timnath Reservoir has no grade, but these lakes within a short drive do.
Nearby Lakes in Larimer County
Frequently asked questions about Timnath Reservoir
Where is Timnath Reservoir?
- Timnath Reservoir is a lake in Larimer County, Colorado. LakeQuality has not rated this lake (UNRATED) — no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years).
What is the water quality grade for Timnath Reservoir?
- Timnath Reservoir in Larimer County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 5.6 ft visibility. Phosphorus: 16.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
Is Timnath Reservoir safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
How deep is Timnath Reservoir?
- No published bathymetric survey covers Timnath Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 20 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
Explore Timnath Reservoir across LakeQuality
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Where this data comes from
6 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX6 samples · 2021
Analytical methods
- Secchi disk depth measurement
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- Nitrogen in Water by Pyrolysis Detection
Monitoring station identifiers (2)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)