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LakeQuality

Brantley Reservoir Deep

Eddy County, New Mexico39,301 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
3.9 ft
Secchi · sampled 2022
Level
3241.77 ft
USGS · Sep 7 · elevation
Trend
No reading
Not enough history
  • Impaired · Fish consumption advisory
  • Limited data

Brantley Reservoir Deep in Eddy County, New Mexico is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.9 ft visibility. Chlorophyll-a (algae): 21 µg/L. Surface area: 39301 acres.

Clarity
3.9 ft
Area
39,301 acres
Chlorophyll-a
21 µg/L
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Why Brantley Reservoir Deep 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 Brantley Reservoir Deep, no nutrient or algae measurement meets the evidence bar (at least 3 samples within 10 years). Sampling here has recorded water clarity and algae (chlorophyll-a), but not phosphorus.

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 NMED and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.

Brantley Reservoir Deep is a 39,301-acre lake in Eddy County, New Mexico.

Source: EPA Water Quality Portal sampling records, NMED, last sampled 2022-04-13. Grade methodology: LakeQuality methodology.

What Brantley Reservoir Deep is good for

From access and monitoring records, not editorial picks.

  • Big water39,301 acres

Swimming Safety

Not rated

Limited data

The letter is not a swimming clearance. Brantley Reservoir Deep is listed impaired under Clean Water Act §303(d) (IR 5) for fish consumption advisory, mercury. Check local advisories before you swim.

Get alerts for Brantley Reservoir Deep

Water quality measurements for Brantley Reservoir Deep

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

Murky, only visible to about 3.9 ft. Chlorophyll-a 21 µg/L. TSI 59.

MetricValueGrade
Water Clarity (Secchi Depth)3.9 ftNot graded
PhosphorusNo recent samples
Chlorophyll-a (Algae)21 µg/LNot graded
Trophic State Index (TSI)59Eutrophic

High nutrients, frequent algae, reduced clarity

Current Conditions

3241.77 ft
Water Elevation

USGS snapshot Sep 7, 2026, 3:00 PM from gauge 08401450 (BRANTLEY LAKE NEAR CARLSBAD, NM). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.

Brantley Reservoir Deep water level: the live USGS gauge reading

Lake Details

CharacteristicValue
Surface Area39,301 acres

No bathymetric survey has been published for Brantley Reservoir Deep, so its depth is not documented here.

Fishing Brantley Reservoir Deep

Reservoir Info (USACE NID)

Brantley Reservoir Deep is a man-made reservoir impounded by the Brantley Dam (completed 1989), built primarily for flood risk reduction on the Pecos River; concrete-type dam, 144 ft tall and 20,850 ft long.

Surface area
39,301 ac
Normal storage
41,054 ac-ft
Max storage
966,300 ac-ft
Drainage area
17,650 sq mi
Hazard class
High
Owner
BUREAU OF RECLAMATION

All listed purposes: Flood Risk Reduction;Irrigation;Recreation.

Source: USACE National Inventory of Dams, NID ID NM00500 · Operator website · Matched by proximity (0.6 km)

EPA Impairment Status

Brantley Reservoir Deep is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).

Causes of impairment

Fish consumption advisoryMercury

Source: EPA ATTAINS assessment unit NM-2205_00 · Official waterbody report · Matched by proximity (2.68 km)

Graded lakes near Brantley Reservoir Deep

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

Nearby Lakes in Eddy County

Frequently asked questions about Brantley Reservoir Deep

Where is Brantley Reservoir Deep?

Brantley Reservoir Deep is a lake in Eddy County, New Mexico. 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 Brantley Reservoir Deep?

Brantley Reservoir Deep in Eddy County, New Mexico is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 3.9 ft visibility. Chlorophyll-a (algae): 21 µg/L. Surface area: 39301 acres.

Is Brantley Reservoir Deep safe to swim in?

The letter is not a swimming clearance. Brantley Reservoir Deep is listed impaired under Clean Water Act §303(d) (IR 5) for fish consumption advisory, mercury. Check local advisories before you swim.

What is the water level at Brantley Reservoir Deep?

The USGS snapshot on this page for Brantley Reservoir Deep is 3241.77 ft of water-surface elevation, recorded Sep 7, 2026, 3:00 PM at gauge 08401450. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.

Planning a trip around Carlsbad Caverns?

Brantley Reservoir Deep is about 30 miles from Carlsbad Caverns National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.

Best time to visit Carlsbad Caverns

Where this data comes from

12 measurements from 1 monitoring station, 2013–2022. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • NM Environmental Dept./SWQB21NMEX_WQX12 samples · 2013–2022

Analytical methods

  • Phosphorus by Colorimetry
  • 10200 H 2 ~ Chlorophyll a-b-c Determination by spectrophotometer
Monitoring station identifiers (1)

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