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LakeQuality

Mcphee Reservoir

Montezuma County, Colorado4,918 acresView mapDirections

NR
Not rated

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.

Water temp
No reading
No gauge
Clarity
10.5 ft
Secchi · sampled 2021
Level
No reading
No gauge
Trend
No reading
Not enough history
  • 139 ft max depth
  • Limited data

Mcphee Reservoir in Montezuma County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Phosphorus: 105 µg/L. Chlorophyll-a (algae): 0.9 µg/L. Surface area: 4918 acres.

Clarity
10.5 ft
Max depth
~139 ft est.
Area
4,918 acres
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Watch Mcphee Reservoir’s letter

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Why Mcphee 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 Mcphee 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.

Mcphee Reservoir is a 4,918-acre lake in Montezuma County, Colorado with an estimated average depth of about 139 feet.

Source: EPA Water Quality Portal sampling records, CDPHE, last sampled 2021-07-07. Grade methodology: LakeQuality methodology.

What Mcphee Reservoir is good for

From access and monitoring records, not editorial picks.

  • Clear water10.5 ft of visibility
  • Camping2 public campgrounds nearby
  • Big water4,918 acres

Swimming Safety

Not rated

Limited data

The letter is not a swimming clearance. Mcphee Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.

Get alerts for Mcphee Reservoir

Water quality measurements for Mcphee Reservoir

These readings exist but are not enough for an A–F grade — see why.

Good clarity, visible to about 10.5 ft. Phosphorus 105 µg/L. Chlorophyll-a 0.9 µg/L. TSI 48.

MetricValueGrade
Water Clarity (Secchi Depth)10.5 ftNot graded
Phosphorus105 µg/LNot graded
Chlorophyll-a (Algae)0.9 µg/LNot graded
Trophic State Index (TSI)48Mesotrophic

Moderate nutrients, good water quality

Lake Details

CharacteristicValue
Maximum Depth~139 ft est.
Average Depth~62 ft est.
Surface Area4,918 acres

Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Colorado has not published bathymetry for Mcphee Reservoir.

Lake Size & Watershed

Watershed (drainage) area
805 sq mi
Shoreline
34.4 mi
Elevation
6,926 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.

Recreation & Access

2
Campgrounds

Public campgrounds near Mcphee Reservoir

  • House Creek Cg1.0 km
  • Mcphee Cg1.8 km

Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes

Fishing Mcphee Reservoir

Reservoir Info (USACE NID)

Mcphee Reservoir is a man-made reservoir impounded by the Mcphee Great Cut Dike (completed 1983), built primarily for fish and wildlife pond on the Delores River; earth-type dam, 75 ft tall and 1,900 ft long.

Surface area
4,918 ac
Normal storage
381,000 ac-ft
Max storage
399,200 ac-ft
Hazard class
High
Owner
BUREAU OF RECLAMATION

All listed purposes: Fish and Wildlife Pond;Irrigation;Recreation;Hydroelectric;Water Supply.

Source: USACE National Inventory of Dams, NID ID CO02707 · Operator website

EPA Impairment Status

Mcphee Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).

Causes of impairment

Mercury

A Total Maximum Daily Load (TMDL) plan has been approved.

Source: EPA ATTAINS assessment unit COSJDO04b_B · Official waterbody report

Graded lakes near Mcphee Reservoir

Mcphee Reservoir has no grade, but these lakes within a short drive do.

Nearby Lakes in Montezuma County

Frequently asked questions about Mcphee Reservoir

Where is Mcphee Reservoir?

Mcphee Reservoir is a lake in Montezuma 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 Mcphee Reservoir?

Mcphee Reservoir in Montezuma County, Colorado is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Phosphorus: 105 µg/L. Chlorophyll-a (algae): 0.9 µg/L. Surface area: 4918 acres.

Is Mcphee Reservoir safe to swim in?

The letter is not a swimming clearance. Mcphee Reservoir is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.

How deep is Mcphee Reservoir?

No published bathymetric survey covers Mcphee Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 139 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 4918 acres.

Are there campgrounds on Mcphee Reservoir?

Mcphee Reservoir has 2 public campgrounds from USGS The National Map within 5 km, including House Creek Cg, Mcphee Cg. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.

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-WQCD21COL001_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

Impairment status from EPA ATTAINS 303(d) database

Lake size & watershed from HydroLAKES (HydroSHEDS)

Public campgrounds from USGS The National Map Structures, within about 3 miles