Sumner Lake Dam
De Baca County, New Mexico7,615 acresView mapDirections
Not enough samples to grade — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. No letter yet. Here is what we do have.
- Impaired · Mercury
- Public access
- Limited data
Sumner Lake Dam in De Baca County, New Mexico is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.9 ft visibility. Chlorophyll-a (algae): 5.1 µg/L. Surface area: 7615 acres.
- Clarity
- 4.9 ft
- Area
- 7,615 acres
- Chlorophyll-a
- 5.1 µg/L
- Trend
- ↓ Declining
- Public access
- Yes
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Watch Sumner Lake Dam’s letter
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Why Sumner Lake Dam 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 Sumner Lake Dam, the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity. 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.
Sumner Lake Dam is a 7,615-acre lake in De Baca County, New Mexico. Overall water quality is declining over recent sampling years. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, NMED, last sampled 2020-08-11. Grade methodology: LakeQuality methodology.
What Sumner Lake Dam is good for
From access and monitoring records, not editorial picks.
- Boat launch1 documented ramp
- Big water7,615 acres
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Sumner Lake Dam is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
Water quality measurements for Sumner Lake Dam
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 4.9 ft. Chlorophyll-a 5.1 µg/L. TSI 50.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 4.9 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | 5.1 µg/L | Not graded |
| Trophic State Index (TSI) | 50 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Current Conditions
USGS snapshot Sep 7, 2026, 3:45 PM from gauge 08384000 (LAKE SUMNER NR FORT SUMNER, NM). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
→ Sumner Lake Dam water level: the live USGS gauge reading
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 7,615 acres |
| Public Access | Yes |
No bathymetric survey has been published for Sumner Lake Dam, so its depth is not documented here.
Recreation & Access
- Sumner Lake State ParkPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fishing Sumner Lake Dam
Water Quality Trend: ↓ Declining
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.27 m/yr | 2 |
Reservoir Info (USACE NID)
Sumner Lake Dam is a man-made reservoir impounded by the Sumner Dam (completed 1937), built primarily for flood risk reduction on the Pecos River; earth-type dam, 164 ft tall and 3,084 ft long.
- Surface area
- 7,615 ac
- Normal storage
- 63,690 ac-ft
- Max storage
- 227,683 ac-ft
- Drainage area
- 4,511.27 sq mi
- Hazard class
- High
- Owner
- BUREAU OF RECLAMATION
All listed purposes: Flood Risk Reduction;Irrigation.
Source: USACE National Inventory of Dams, NID ID NM00130 · Operator website
EPA Impairment Status
Sumner Lake Dam 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 NM-2210_00 · Official waterbody report · Matched by proximity (2.57 km)
Graded lakes near Sumner Lake Dam
Sumner Lake Dam has no grade, but these lakes within a short drive do.
Nearby Lakes in De Baca County
Frequently asked questions about Sumner Lake Dam
Where is Sumner Lake Dam?
- Sumner Lake Dam is a lake in De Baca County, New Mexico. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Sumner Lake Dam?
- Sumner Lake Dam in De Baca County, New Mexico is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 4.9 ft visibility. Chlorophyll-a (algae): 5.1 µg/L. Surface area: 7615 acres.
Is Sumner Lake Dam safe to swim in?
- The letter is not a swimming clearance. Sumner Lake Dam is listed impaired under Clean Water Act §303(d) (IR 5) for mercury. Check local advisories before you swim.
What is the water level at Sumner Lake Dam?
- The USGS snapshot on this page for Sumner Lake Dam is 33.37 ft of gage height, recorded Sep 7, 2026, 3:45 PM at gauge 08384000. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Are there boat ramps on Sumner Lake Dam?
- Sumner Lake Dam has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Sumner Lake State Park. Public access is listed as yes.
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Where this data comes from
7 measurements from 1 monitoring station, 2019–2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- NM Environmental Dept./SWQB
21NMEX_WQX7 samples · 2019–2020
Analytical methods
- 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
Named boat-access points from the USGS National Boat Ramps inventory