Trinidad Reservoir
Las Animas County, Colorado1,442 acresView mapDirections
Nutrients and algae sit mid-range for this region.
↑ up from D at the last regrade
- Oligotrophic
- #1 of 1 in the county
- 123 ft max depth
- Public access
- Limited data
Trinidad Reservoir in Las Animas County, Colorado has a water quality grade of C (Fair). Water clarity: 6.6 ft visibility. Phosphorus: 46 µg/L. Chlorophyll-a (algae): 1.1 µg/L. Surface area: 1442 acres.
- Clarity
- 6.6 ft
- Max depth
- ~123 ft est.
- Area
- 1,442 acres
- Type
- Oligotrophic
- Public access
- Yes
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Watch Trinidad Reservoir’s letter
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Trinidad Reservoir is a 1,442-acre cold, clear oligotrophic lake in Las Animas County, Colorado with an estimated average depth of about 123 feet. Water quality is graded C based on 3 sampling years through 2024. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2024-09-11. Grade methodology: LakeQuality methodology.
What Trinidad Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water1,442 acres
Swimming Safety
Grade onlyLimited data
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 C is nutrients and algae, not a swimming clearance. Trinidad Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury), oxygen depletion (low DO). Check local advisories before you swim.
Water Quality Grade: C (Fair)
Murky, only visible to about 6.6 ft. Phosphorus 46 µg/L. Chlorophyll-a 1.1 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.6 ft | Not graded |
| Phosphorus | 46 µg/L | Poor |
| Chlorophyll-a (Algae) | 1.1 µg/L | Good |
| Trophic State Index (TSI) | 47 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
→ Trinidad Reservoir water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~123 ft est. |
| Surface Area | 1,442 acres |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for Trinidad 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.
Recreation & Access
- Trinidad Lake State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Trinidad Reservoir
Reservoir Info (USACE NID)
Trinidad Reservoir is a man-made reservoir impounded by the Trinidad Dam (completed 1976), built primarily for flood risk reduction on the Purgatoire River; earth-type dam, 203 ft tall and 6,610 ft long.
- Surface area
- 1,442 ac
- Normal storage
- 71,779 ac-ft
- Max storage
- 164,930 ac-ft
- Drainage area
- 671 sq mi
- Hazard class
- High
- Owner
- USACE - Albuquerque District
All listed purposes: Flood Risk Reduction;Other;Irrigation;Recreation.
Source: USACE National Inventory of Dams, NID ID CO00050 · Operator website
EPA Impairment Status
Trinidad Reservoir 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 COARLA15_B · Official waterbody report
County Ranking
Ranked #1 of 1 lakes in Las Animas County
Nearby Lakes in Las Animas County
Frequently asked questions about Trinidad Reservoir
Where is Trinidad Reservoir?
- Trinidad Reservoir is a lake in Las Animas County, Colorado. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Trinidad Reservoir?
- Trinidad Reservoir in Las Animas County, Colorado has a water quality grade of C (Fair). Water clarity: 6.6 ft visibility. Phosphorus: 46 µg/L. Chlorophyll-a (algae): 1.1 µg/L. Surface area: 1442 acres.
Is Trinidad Reservoir safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Trinidad Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury), oxygen depletion (low DO). Check local advisories before you swim.
How deep is Trinidad Reservoir?
- No published bathymetric survey covers Trinidad Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 123 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 1442 acres.
Are there boat ramps on Trinidad Reservoir?
- Trinidad Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Trinidad Lake State Park. Public access is listed as yes.
Explore Trinidad Reservoir across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Colorado's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
24 measurements from 4 monitoring stations, 2022–2024. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX24 samples · 2022–2024
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 (4)
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory