Rifle Gap Reservoir
Garfield County, Colorado435 acresView 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.
- 17 ft max depth
- Public access
- Limited data
Rifle Gap Reservoir in Garfield County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7.9 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 0.5 µg/L. Surface area: 435 acres.
- Clarity
- 7.9 ft
- Max depth
- ~17 ft est.
- Area
- 435 acres
- Public access
- Yes
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Why Rifle Gap 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 Rifle Gap 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.
Rifle Gap Reservoir is a 435-acre lake in Garfield County, Colorado with an estimated average depth of about 17 feet. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2023-05-09. Grade methodology: LakeQuality methodology.
What Rifle Gap Reservoir is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Rifle Gap Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury). Check local advisories before you swim.
Water quality measurements for Rifle Gap Reservoir
These readings exist but are not enough for an A–F grade — see why.
Moderate clarity, visible to about 7.9 ft. Phosphorus 10 µg/L. Chlorophyll-a 0.5 µg/L. TSI 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.9 ft | Not graded |
| Phosphorus | 10 µg/L | Not graded |
| Chlorophyll-a (Algae) | 0.5 µg/L | Not graded |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
→ Rifle Gap Reservoir water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~17 ft est. |
| Surface Area | 435 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 Rifle Gap 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
- Rifle Gap State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Rifle Gap Reservoir
Reservoir Info (USACE NID)
Rifle Gap Reservoir is a man-made reservoir impounded by the Rifle Gap Dam (completed 1967), built primarily for irrigation on the Rifle Creek; earth-type dam, 157 ft tall and 1,450 ft long.
- Surface area
- 435 ac
- Normal storage
- 12,168 ac-ft
- Max storage
- 18,261 ac-ft
- Drainage area
- 136.52 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Irrigation;Recreation.
Source: USACE National Inventory of Dams, NID ID CO01692 · Operator website
EPA Impairment Status
Rifle Gap 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 COLCLC20_B · Official waterbody report
Graded lakes near Rifle Gap Reservoir
Rifle Gap Reservoir has no grade, but these lakes within a short drive do.
Nearby Lakes in Garfield County
Frequently asked questions about Rifle Gap Reservoir
Where is Rifle Gap Reservoir?
- Rifle Gap Reservoir is a lake in Garfield 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 Rifle Gap Reservoir?
- Rifle Gap Reservoir in Garfield County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 7.9 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 0.5 µg/L. Surface area: 435 acres.
Is Rifle Gap Reservoir safe to swim in?
- The letter is not a swimming clearance. Rifle Gap Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, metals (other than mercury). Check local advisories before you swim.
How deep is Rifle Gap Reservoir?
- No published bathymetric survey covers Rifle Gap Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 17 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 435 acres.
Are there boat ramps on Rifle Gap Reservoir?
- Rifle Gap Reservoir has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Rifle Gap State Park. Public access is listed as yes.
Explore Rifle Gap Reservoir across LakeQuality
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Where this data comes from
12 measurements from 4 monitoring stations, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Colorado Dept. of Public Health & Environment-WQCD
21COL001_WQX12 samples · 2022–2023
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