Chatfield Reservoir
Jefferson County, Colorado1,150 acresView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↑ up from D at the last regrade
- Eutrophic
- #1 of 1 in the county
- 64 ft max depth
- Public access
- Limited data
Chatfield Reservoir in Jefferson County, Colorado has a water quality grade of B (Good). Water clarity: 6.2 ft visibility. Phosphorus: 27 µg/L. Surface area: 1150 acres.
- Clarity
- 6.2 ft
- Max depth
- ~64 ft est.
- Area
- 1,150 acres
- Type
- Eutrophic
- Public access
- Yes
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Watch Chatfield Reservoir’s letter
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Chatfield Reservoir is a 1,150-acre productive, nutrient-rich eutrophic lake in Jefferson County, Colorado with an estimated average depth of about 64 feet. Water quality is graded B based on 2 sampling years through 2020. Limited fish-species data available. Public access is available with 2 public boat landings.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2020-08-21. Grade methodology: LakeQuality methodology.
What Chatfield Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch2 documented ramps
- Big water1,150 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 B is nutrients and algae, not a swimming clearance. Chatfield Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury). Check local advisories before you swim.
Water Quality Grade: B (Good)
Murky, only visible to about 6.2 ft. Phosphorus 27 µg/L. TSI 51. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 ft | Not graded |
| Phosphorus | 27 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~64 ft est. |
| Surface Area | 1,150 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 Chatfield 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
- Chatfield State ParkPublic
- Chatfield State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Chatfield Reservoir
Reservoir Info (USACE NID)
Chatfield Reservoir is a man-made reservoir impounded by the Chatfield Dam (completed 1973), built primarily for flood risk reduction on the South Platte River; earth-type dam, 148 ft tall and 13,136 ft long.
- Surface area
- 1,150 ac
- Normal storage
- 20,000 ac-ft
- Max storage
- 355,000 ac-ft
- Drainage area
- 3,018 sq mi
- Hazard class
- High
- Owner
- USACE - Omaha District
All listed purposes: Flood Risk Reduction;Irrigation;Recreation.
Source: USACE National Inventory of Dams, NID ID CO01281 · Operator website
EPA Impairment Status
Chatfield Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit COSPUS06b_A · Official waterbody report
County Ranking
Ranked #1 of 1 lakes in Jefferson County
Nearby Lakes in Jefferson County
Frequently asked questions about Chatfield Reservoir
Where is Chatfield Reservoir?
- Chatfield Reservoir is a lake in Jefferson County, Colorado. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Chatfield Reservoir?
- Chatfield Reservoir in Jefferson County, Colorado has a water quality grade of B (Good). Water clarity: 6.2 ft visibility. Phosphorus: 27 µg/L. Surface area: 1150 acres.
Is Chatfield Reservoir safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Chatfield Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for metals (other than mercury). Check local advisories before you swim.
How deep is Chatfield Reservoir?
- No published bathymetric survey covers Chatfield Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 64 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 1150 acres.
Are there boat ramps on Chatfield Reservoir?
- Chatfield Reservoir has 2 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Chatfield State Park, Chatfield State Park. Public access is listed as yes.
Explore Chatfield Reservoir across LakeQuality
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Where this data comes from
9 measurements from 2 monitoring stations, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX9 samples · 2020
Analytical methods
- Secchi disk depth measurement
- Phosphorus by Colorimetry
- 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
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