Lake Sumner
Lake Sumner held 14,779 acre-feet on Nov 2, 2026, 41.1% of its conservation pool: normal for the date (the middle of past years is 45.5%).
A flood-control dam with a conservation or recreation pool beneath a much larger flood pool. On Pecos River. Pecos basin.
14,779acre-feet held, Nov 2, 2026
41.1%of the conservation pool (35,917 acre-feet)
normalfor the date; typical 45%
Up 7,220acre-feet over 30 days
13,313acre-feet a year ago (37.1%)
0days this year above the conservation pool
These lakes hold a normal "conservation" or recreation pool and keep a much larger space empty to catch floods. Percent is measured against the conservation pool, so a reading above 100% means flood water is being held back.
Last 365 days
Percent of the conservation pool, against the middle and spread of the same date in other years (the shaded bands: the middle half and the 10th to 90th percentile of past years).
- Median of past years
- Percent of conservation pool
- 10th–90th percentile of past years
- Middle half of past years
Show the data as a table
Year by year
The highest, average and lowest percent of the conservation pool in each calendar year. The latest year is partial. Years whose capacity is less certain are marked in the table below.
- Highest
- Average
- Lowest
Show the data as a table
The comparison uses 30 years of 1991-2020 whose capacity figure is published, current-table, high- or medium-confidence, 1991–2020, pooling 3 days either side of each date.
Readings are what the operating agencies report; we have not audited the latest values. Reclamation labels its data "provisional and subject to revision unless otherwise noted."
Year-by-year table, with how well capacity is known
| Year | Days | Most (acre-feet) | Average | Least | Highest % | Average % | Lowest % | Capacity figure |
|---|---|---|---|---|---|---|---|---|
| 2026 | 306 | 24,003 | 13,333 | 2,675 | 66.8% | 37.1% | 7.4% | Capacity published by the operator for that year |
| 2025 | 365 | 22,691 | 17,805 | 9,021 | 63.2% | 49.6% | 25.1% | Capacity published by the operator for that year |
| 2024 | 366 | 24,270 | 14,441 | 4,678 | 67.6% | 40.2% | 13.0% | Capacity published by the operator for that year |
| 2023 | 365 | 28,065 | 15,755 | 8,180 | 78.1% | 43.9% | 22.8% | Capacity published by the operator for that year |
| 2022 | 365 | 16,993 | 11,548 | 3,166 | 47.3% | 32.2% | 8.8% | Capacity published by the operator for that year |
| 2021 | 365 | 19,181 | 11,178 | 4,662 | 53.4% | 31.1% | 13.0% | Capacity published by the operator for that year |
| 2020 | 366 | 27,882 | 15,522 | 4,808 | 77.6% | 43.2% | 13.4% | Capacity published by the operator for that year |
| 2019 | 365 | 33,819 | 23,959 | 13,710 | 94.2% | 66.7% | 38.2% | Capacity published by the operator for that year |
| 2018 | 365 | 42,930 | 28,906 | 17,761 | 119.5% | 80.5% | 49.5% | Capacity published by the operator for that year |
| 2017 | 365 | 39,123 | 28,596 | 19,452 | 108.9% | 79.6% | 54.2% | Capacity published by the operator for that year |
| 2016 | 366 | 46,543 | 31,111 | 17,701 | 129.6% | 86.6% | 49.3% | Capacity published by the operator for that year |
| 2015 | 365 | 47,102 | 38,097 | 28,289 | 131.1% | 106.1% | 78.8% | Capacity published by the operator for that year |
| 2014 | 365 | 44,945 | 35,723 | 24,990 | 125.1% | 99.5% | 69.6% | Capacity published by the operator for that year |
| 2013 | 365 | 36,830 | 14,843 | 3,060 | 102.5% | 41.3% | 8.5% | Capacity published by the operator for that year |
| 2012 | 366 | 16,618 | 6,075 | 1,712 | 46.3% | 16.9% | 4.8% | Capacity published by the operator for that year |
| 2011 | 365 | 25,107 | 10,675 | 1,964 | 69.9% | 29.7% | 5.5% | Capacity recovered from the record, well supported |
| 2010 | 365 | 31,447 | 19,664 | 13,689 | 87.5% | 54.7% | 38.1% | Capacity recovered from the record, well supported |
| 2009 | 365 | 24,518 | 16,573 | 7,764 | 68.2% | 46.1% | 21.6% | Capacity recovered from the record, well supported |
| 2008 | 366 | 28,612 | 18,978 | 0 | 79.6% | 52.8% | 0.0% | Capacity recovered from the record, well supported |
| 2007 | 365 | 73,837 | 25,296 | 17,626 | 205.4% | 70.4% | 49.0% | Capacity recovered from the record, well supported |
| 2006 | 365 | 35,331 | 20,675 | 11,778 | 93.9% | 54.9% | 31.3% | Capacity recovered from the record, well supported |
| 2005 | 365 | 43,954 | 33,610 | 10,206 | 116.8% | 89.3% | 27.1% | Capacity recovered from the record, well supported |
| 2004 | 366 | 23,573 | 9,621 | 2,050 | 62.6% | 25.6% | 5.4% | Capacity recovered from the record, well supported |
| 2003 | 365 | 14,723 | 8,501 | 1,619 | 39.1% | 22.6% | 4.3% | Capacity recovered from the record, well supported |
| 2002 | 365 | 14,232 | 4,716 | 0 | 37.8% | 12.5% | 0.0% | Capacity recovered from the record, well supported |
| 2001 | 365 | 40,627 | 18,760 | 3,193 | 107.9% | 49.8% | 8.5% | Capacity recovered from the record, well supported |
| 2000 | 366 | 36,440 | 20,668 | 6,510 | 84.0% | 47.7% | 15.0% | Capacity recovered from the record, well supported |
| 1999 | 365 | 43,940 | 32,978 | 19,580 | 101.3% | 76.0% | 45.2% | Capacity recovered from the record, well supported |
| 1998 | 365 | 42,230 | 24,509 | 8,890 | 97.4% | 56.5% | 20.5% | Capacity recovered from the record, well supported |
| 1997 | 365 | 42,790 | 31,223 | 14,820 | 98.7% | 72.0% | 34.2% | Capacity recovered from the record, well supported |
| 1996 | 366 | 43,320 | 24,010 | 5,190 | 99.9% | 55.4% | 12.0% | Capacity recovered from the record, well supported |
| 1995 | 365 | 37,070 | 26,932 | 19,910 | 85.5% | 62.1% | 45.9% | Capacity recovered from the record, well supported |
| 1994 | 365 | 44,880 | 27,738 | 12,200 | 103.5% | 64.0% | 28.1% | Capacity recovered from the record, well supported |
| 1993 | 365 | 44,190 | 30,259 | 13,860 | 101.9% | 69.8% | 32.0% | Capacity recovered from the record, well supported |
| 1992 | 366 | 64,040 | 39,088 | 12,170 | 147.7% | 90.1% | 28.1% | Capacity recovered from the record, well supported |
| 1991 | 365 | 56,770 | 24,669 | 2,600 | 130.6% | 56.7% | 6.0% | Capacity recovered from the record, well supported |
| 1990 | 365 | 32,200 | 18,091 | 5,350 | 74.1% | 41.6% | 12.3% | Capacity recovered from the record, well supported |
| 1989 | 365 | 36,100 | 22,583 | 12,900 | 83.0% | 51.9% | 29.7% | Capacity recovered from the record, well supported |
| 1988 | 366 | 46,469 | 29,122 | 13,730 | 106.9% | 67.0% | 31.6% | Capacity recovered from the record, well supported |
| 1987 | 365 | 67,444 | 49,809 | 27,446 | 132.8% | 98.1% | 54.0% | Capacity recovered from the record, well supported |
| 1986 | 365 | 68,111 | 45,859 | 27,080 | 134.1% | 90.3% | 53.3% | Capacity recovered from the record, well supported |
| 1985 | 365 | 46,200 | 32,387 | 8,680 | 91.0% | 63.8% | 17.1% | Capacity recovered from the record, well supported |
| 1984 | 366 | 32,830 | 20,658 | 9,210 | 64.6% | 40.7% | 18.1% | Capacity recovered from the record, well supported |
| 1983 | 365 | 38,900 | 20,032 | 4,190 | 76.6% | 39.4% | 8.2% | Capacity recovered from the record, well supported |
| 1982 | 365 | 48,360 | 23,517 | 2,840 | 95.2% | 46.3% | 5.6% | Capacity recovered from the record, well supported |
| 1981 | 365 | 40,350 | 27,100 | 2,160 | 78.9% | 53.0% | 4.2% | Capacity recovered from the record, well supported |
| 1980 | 366 | 91,160 | 43,695 | 1,680 | 178.3% | 85.5% | 3.3% | Capacity recovered from the record, well supported |
| 1979 | 365 | 102,500 | 68,918 | 22,920 | 200.4% | 134.8% | 44.8% | Capacity recovered from the record, well supported |
| 1978 | 365 | 48,360 | 17,461 | 2,460 | 94.6% | 34.1% | 4.8% | Capacity recovered from the record, well supported |
| 1977 | 365 | 40,120 | 23,513 | 3,710 | 78.5% | 46.0% | 7.3% | Capacity recovered from the record, well supported |
| 1976 | 366 | 39,900 | 16,817 | 3,440 | 78.0% | 32.9% | 6.7% | Capacity recovered from the record, well supported |
| 1975 | 365 | 63,340 | 32,862 | 4,000 | 123.9% | 64.3% | 7.8% | Capacity recovered from the record, well supported |
| 1974 | 365 | 102,200 | 46,384 | 3,280 | 199.9% | 90.7% | 6.4% | Capacity recovered from the record, well supported |
| 1973 | 356 | 112,400 | 98,241 | 80,520 | 219.8% | 192.1% | 157.5% | Capacity recovered from the record, well supported |
| 1972 | 349 | 80,170 | 36,800 | 3,680 | 156.8% | 72.0% | 7.2% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1971 | 365 | 59,770 | 33,782 | 4,630 | 116.9% | 66.1% | 9.1% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1970 | 365 | 85,290 | 58,859 | 27,440 | 166.8% | 115.1% | 53.7% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1969 | 365 | 74,740 | 51,891 | 3,490 | 146.2% | 101.5% | 6.8% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1968 | 366 | 74,580 | 54,292 | 19,520 | 145.8% | 106.2% | 38.2% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1967 | 365 | 72,060 | 51,561 | 10,800 | 140.9% | 100.8% | 21.1% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1966 | 365 | 65,960 | 41,926 | 2,520 | 129.0% | 82.0% | 4.9% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
| 1965 | 92 | 45,450 | 41,526 | 36,100 | 88.9% | 81.2% | 70.6% | Before elevation records began; capacity extrapolatednot used for "this date in other years" |
About this reservoir
Reclamation storage for the Carlsbad Project on the Pecos in De Baca County, completed in 1937. Water is released in blocks to move it down to Brantley and Carlsbad.
How to use these numbers
- Carlsbad Project supply. With Brantley and Santa Rosa, Sumner holds the Pecos irrigation supply.
- Block releases. Release records show the large block releases used to move water down the Pecos efficiently.
Read before quoting a number
- The top of the active conservation pool was lowered in June 2012 for dam maintenance, to 4,260.9 ft. The earlier, higher pool is not published in CWMS, so every year is measured against the reduced pool. Before 2012 that overstates percent full, and it counts as flood storage water that was then ordinary conservation storage. Percentages above 100% before 2012 should not be read as floods.
- Sumner has a flood pool above its conservation pool (Flood Risk Reduction is its primary purpose in the dam registry), so it is treated as a flood-control reservoir here.
- Pre-2007 capacities are derived from an elevation and storage pairing that is noisy in this record. Treat individual early years as approximate.
The dam
| Dam | Sumner Dam (formerly Alamogordo Dam) |
|---|---|
| Owner | Bureau of Reclamation (Federal) |
| Operated with | Bureau of Reclamation |
| Type | Earth |
| Purposes, per the dam registry | Flood Risk Reduction, Irrigation |
| Completed | 1937 |
| Height | 164 feet |
| Hazard class | High |
| Registry capacity | 227,683 acre-feet at most, 63,690 normal. Owner-reported and not corrected for sediment. |
National Inventory of Dams, U.S. Army Corps of Engineers.
How capacity is known
Capacity comes from the operator's elevation-to-storage table (USBR, effective 2026-01-01), checked against the storage the operator reports. Since the table took effect, it reproduces reported storage from reported elevation to within 0 acre-feet in the median (0.00% of storage), across 299 days. Where an older table was in force, we recover its capacity from the record and say how well supported it is.
| Pool | Elevation (ft) | Capacity now (acre-feet) | Where it comes from |
|---|---|---|---|
| Top of conservation poolused as 100% | 4,260.9 | 35,211 | CWMS level Sumner.Elev.Inst.0.Top of Conservation dated 2025-02-12Top of Active Conservation (2012) Reduction of Maintenance |
| Top of flood pool | 4,283.9 | 122,804 | CWMS level Sumner.Elev.Inst.0.Top of Flood dated 2014-01-01 |
| Top of dam | 4,302.9 | 218,990 | CWMS level Sumner.Elev.Inst.0.Top of Dam dated 2014-08-01 |
| Top of entitlement pool | 4,260.9 | 35,211 | CWMS level Sumner.Elev.Inst.0.Top of Entitlement dated 2025-01-01Top of Entitlement, 2025 |
| Top of inactive pool | 4,232.3 | 2,374 | CWMS level Sumner.Elev.Inst.0.Top of Inactive dated 2024-01-01 |
Capacity over time (8 tables in force)
| Period | Capacity (acre-feet) | How well supported |
|---|---|---|
| 1973-01-01 to 1981-12-311973-1981 table | 51,135 | Capacity recovered from the record, well supported |
| 1982-01-01 to 1984-12-311982-1984 table | 50,797 | Capacity recovered from the record, well supported |
| 1985-01-01 to 1987-12-311985-1987 table | 50,797 | Capacity recovered from the record, well supported |
| 1988-01-01 to 1991-12-311988-1991 table | 43,475 | Capacity recovered from the record, well supported |
| 1992-01-01 to 1996-09-161992-1996 table | 43,366 | Capacity recovered from the record, well supported |
| 1999-09-29 to 2000-12-311999-2000 table | 43,366 | Capacity recovered from the record, well supported |
| 2001-01-01 to 2006-12-312001-2006 table | 37,646 | Capacity recovered from the record, well supported |
| 2007-01-01 to 2026-11-022007-2026 table | 35,944 | Capacity recovered from the record, well supported |
Rivers
Data and sources
Record from 1965 (62 years with readings), through Nov 2, 2026. Where several agencies report the same reservoir, we take each day's value from the first in this list that has one:
- Bureau of Reclamation HydroData: 22,224 days
- U.S. Geological Survey NWIS: 63 days
Year by year (CSV) · Last 365 days (CSV)
Credit: Bureau of Reclamation HydroData; U.S. Geological Survey NWIS; National Inventory of Dams (U.S. Army Corps of Engineers). Capacity analysis by New Mexico Water. Data accessed November 4, 2026.