Timnath Reservoir
Larimer County, ColoradoView mapDirections
Colorado WQCD publishes the water-quality measurements for Timnath Reservoir. Here is what has been measured.
- 20 ft max depth
- Limited data
Timnath Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. Water clarity: 5.6 ft visibility. Phosphorus: 16.5 µg/L. Chlorophyll-a (algae): 10.7 µg/L.
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. Methodology: how these readings are compared.
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Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Timnath Reservoir is safe to swim in today is a call for the Water Quality Control Division of the Colorado Department of Public Health and Environment and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Timnath Reservoir
These are the measurements Colorado WQCD publishes for Timnath Reservoir, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 5.6 ft. Phosphorus 16.5 µg/L. Chlorophyll-a 10.7 µg/L. TSI 50.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 5.6ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 16.5µg/L | Measured, not scored The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. |
| Chlorophyll-a (algae) | 10.7µg/L | Measured, not scored The green pigment in algae — a direct measure of how much algae is in the water. |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 50 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Timnath Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max 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
Watershed (drainage) area
19 sq mi
HydroLAKES / HydroSHEDS
Surface area
576 acres
HydroLAKES / HydroSHEDS
Shoreline
5.2 mi
HydroLAKES / HydroSHEDS
Elevation
4,908 ft
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.
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Frequently asked questions about Timnath Reservoir
Where is Timnath Reservoir?
- Timnath Reservoir is a lake in Larimer County, Colorado. Its water-quality measurements are published by Colorado WQCD and shown on this page as reported.
What is the water quality of Timnath Reservoir?
- Timnath Reservoir in Larimer County, Colorado has water-quality measurements published by Colorado WQCD, shown here as reported. 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?
- Nutrient and algae readings are 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.
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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)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Lake size & watershed from HydroLAKES (HydroSHEDS)