Heron Reservoir
Heron Reservoir held 66,318 acre-feet on Nov 2, 2026, 16.6% of its full pool: much below normal for the date (the middle of past years is 59.6%).
A storage reservoir: it holds water for later release. On Willow Creek, at the Rio Chama. Rio Grande (Rio Chama) basin.
These reservoirs hold water for later use. Percent full is the water held divided by what the reservoir can hold at its full pool, using the capacity that applied at the time.
Last 365 days
Percent of the full 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 full 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 full 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 | 66,318 | 38,515 | 26,432 | 16.6% | 9.6% | 6.6% | The operator's current table fits the record |
| 2025 | 365 | 79,926 | 56,411 | 27,407 | 20.0% | 14.1% | 6.9% | The operator's current table fits the record |
| 2024 | 366 | 139,544 | 101,396 | 65,199 | 34.9% | 25.3% | 16.3% | The operator's current table fits the record |
| 2023 | 365 | 167,700 | 96,487 | 36,247 | 41.9% | 24.1% | 9.1% | The operator's current table fits the record |
| 2022 | 365 | 84,874 | 55,073 | 40,250 | 21.2% | 13.8% | 10.1% | The operator's current table fits the record |
| 2021 | 365 | 99,258 | 61,845 | 40,022 | 24.8% | 15.5% | 10.0% | The operator's current table fits the record |
| 2020 | 366 | 137,806 | 94,108 | 53,244 | 34.4% | 23.5% | 13.3% | The operator's current table fits the record |
| 2019 | 365 | 193,157 | 116,160 | 56,095 | 48.3% | 29.0% | 14.0% | The operator's current table fits the record |
| 2018 | 365 | 168,197 | 118,667 | 56,294 | 42.0% | 29.7% | 14.1% | The operator's current table fits the record |
| 2017 | 365 | 196,556 | 135,553 | 65,765 | 49.1% | 33.9% | 16.4% | The operator's current table fits the record |
| 2016 | 366 | 138,456 | 94,957 | 65,684 | 34.6% | 23.7% | 16.4% | The operator's current table fits the record |
| 2015 | 365 | 140,920 | 88,756 | 62,759 | 35.2% | 22.2% | 15.7% | The operator's current table fits the record |
| 2014 | 365 | 112,918 | 83,591 | 65,700 | 28.2% | 20.9% | 16.4% | The operator's current table fits the record |
| 2013 | 365 | 167,062 | 118,780 | 85,739 | 41.8% | 29.7% | 21.4% | The operator's current table fits the record |
| 2012 | 366 | 266,483 | 223,432 | 167,274 | 66.6% | 55.9% | 41.8% | The operator's current table fits the record |
| 2011 | 365 | 304,607 | 250,193 | 223,328 | 75.9% | 62.3% | 55.6% | Capacity recovered from the record, well supported |
| 2010 | 365 | 334,670 | 276,503 | 226,680 | 83.4% | 68.9% | 56.5% | Capacity recovered from the record, well supported |
| 2009 | 365 | 343,453 | 282,514 | 243,441 | 85.6% | 70.4% | 60.7% | Capacity recovered from the record, well supported |
| 2008 | 366 | 321,115 | 261,739 | 196,413 | 80.0% | 65.2% | 48.9% | Capacity recovered from the record, well supported |
| 2007 | 365 | 242,023 | 207,567 | 162,305 | 60.3% | 51.7% | 40.4% | Capacity recovered from the record, well supported |
| 2006 | 365 | 211,526 | 185,829 | 150,862 | 52.7% | 46.3% | 37.6% | Capacity recovered from the record, well supported |
| 2005 | 365 | 234,082 | 180,739 | 106,900 | 58.3% | 45.0% | 26.6% | Capacity recovered from the record, well supported |
| 2004 | 366 | 122,861 | 108,599 | 83,211 | 30.6% | 27.1% | 20.7% | Capacity recovered from the record, well supported |
| 2003 | 365 | 198,766 | 153,754 | 123,227 | 49.5% | 38.3% | 30.7% | Capacity recovered from the record, well supported |
| 2002 | 365 | 291,071 | 215,148 | 160,759 | 72.5% | 53.6% | 40.1% | Capacity recovered from the record, well supported |
| 2001 | 365 | 342,486 | 304,447 | 259,478 | 85.3% | 75.9% | 64.7% | Capacity recovered from the record, well supported |
| 2000 | 366 | 379,764 | 326,694 | 267,436 | 94.6% | 81.4% | 66.6% | Capacity recovered from the record, well supported |
| 1999 | 365 | 398,328 | 348,143 | 285,596 | 99.3% | 86.7% | 71.2% | Capacity recovered from the record, well supported |
| 1998 | 365 | 376,510 | 344,733 | 304,353 | 93.8% | 85.9% | 75.8% | Capacity recovered from the record, well supported |
| 1997 | 365 | 366,680 | 328,932 | 263,320 | 91.4% | 82.0% | 65.6% | Capacity recovered from the record, well supported |
| 1996 | 366 | 376,680 | 349,214 | 306,220 | 93.9% | 87.0% | 76.3% | Capacity recovered from the record, well supported |
| 1995 | 365 | 400,330 | 379,896 | 325,334 | 99.8% | 94.7% | 81.1% | Capacity recovered from the record, well supported |
| 1994 | 365 | 402,101 | 383,748 | 334,030 | 100.2% | 95.6% | 83.2% | Capacity recovered from the record, well supported |
| 1993 | 365 | 401,038 | 376,467 | 312,364 | 99.9% | 93.8% | 77.8% | Capacity recovered from the record, well supported |
| 1992 | 366 | 401,569 | 386,692 | 339,634 | 100.1% | 96.4% | 84.6% | Capacity recovered from the record, well supported |
| 1991 | 365 | 401,569 | 379,458 | 313,846 | 100.1% | 94.5% | 78.2% | Capacity recovered from the record, well supported |
| 1990 | 365 | 382,401 | 364,390 | 319,507 | 95.3% | 90.8% | 79.6% | Capacity recovered from the record, well supported |
| 1989 | 365 | 398,740 | 377,903 | 365,334 | 99.4% | 94.2% | 91.0% | Capacity recovered from the record, well supported |
| 1988 | 366 | 396,097 | 383,827 | 345,944 | 98.7% | 95.6% | 86.2% | Capacity recovered from the record, well supported |
| 1987 | 365 | 400,448 | 378,379 | 333,499 | 99.8% | 94.3% | 83.1% | Capacity recovered from the record, well supported |
| 1986 | 365 | 401,569 | 384,143 | 323,610 | 100.1% | 95.7% | 80.6% | Capacity recovered from the record, well supported |
| 1985 | 365 | 401,546 | 376,802 | 317,137 | 100.1% | 93.9% | 79.0% | Capacity recovered from the record, well supported |
| 1984 | 366 | 401,300 | 368,091 | 315,400 | 100.0% | 91.7% | 78.6% | Capacity recovered from the record, well supported |
| 1983 | 365 | 401,100 | 365,538 | 318,600 | 99.9% | 91.1% | 79.4% | Capacity recovered from the record, well supported |
| 1982 | 365 | 401,800 | 354,849 | 291,200 | 100.1% | 88.4% | 72.6% | Capacity recovered from the record, well supported |
| 1981 | 365 | 351,600 | 322,921 | 294,200 | 87.6% | 80.5% | 73.3% | Capacity recovered from the record, well supported |
| 1980 | 366 | 367,900 | 304,729 | 239,100 | 91.7% | 75.9% | 59.6% | Capacity recovered from the record, well supported |
| 1979 | 365 | 301,600 | 231,742 | 145,300 | 75.1% | 57.7% | 36.2% | Capacity recovered from the record, well supported |
| 1978 | 365 | 191,600 | 158,113 | 113,600 | 47.7% | 39.4% | 28.3% | Capacity recovered from the record, well supported |
| 1977 | 365 | 165,700 | 147,409 | 113,600 | 41.3% | 36.7% | 28.3% | Capacity recovered from the record, well supported |
| 1976 | 366 | 207,100 | 184,352 | 140,100 | 51.6% | 45.9% | 34.9% | Capacity recovered from the record, well supported |
| 1975 | 365 | 252,800 | 199,536 | 125,900 | 63.0% | 49.7% | 31.4% | Capacity recovered from the record, well supported |
| 1974 | 1 | 149,900 | 149,900 | 149,900 | 37.4% | 37.4% | 37.4% | Capacity recovered from the record, well supported |
About this reservoir
The San Juan-Chama Project's main storage. Water diverted from San Juan River tributaries in Colorado arrives through the Azotea Tunnel and is held here for the Project's contractors, chiefly the Albuquerque Bernalillo County Water Utility Authority, the Middle Rio Grande Conservancy District and the City of Santa Fe. Heron is operated to store imported San Juan-Chama water, not native Rio Grande water.
How to use these numbers
- Imported supply. Heron storage is the clearest single measure of how much Colorado River basin water New Mexico has banked for the middle Rio Grande. It moves independently of Rio Grande runoff.
- Contractor calls. Releases show when contractors call their water down the Chama, typically for municipal supply or to offset river depletions.
- Snowpack in the San Juan mountains, not the Sangres. Inflow tracks diversions through the Azotea Tunnel, so a good year here can coincide with a poor year on the Rio Grande.
Read before quoting a number
- Reclamation's 2010 survey table published in RISE stops at 7,102 ft, far below the operating range. This report uses the complete operator table held in CWMS instead, which reproduces reported storage exactly.
- Full pool is detected from the record, not taken from a published pool definition.
The dam
| Dam | Heron Dam |
|---|---|
| Owner | Bureau of Reclamation (Federal) |
| Operated with | Bureau of Reclamation |
| Type | Rockfill, Earth |
| Purposes, per the dam registry | Irrigation, Water Supply |
| Completed | 1971 |
| Height | 269 feet |
| Hazard class | High |
| Registry capacity | 429,646 acre-feet at most, 401,317 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 2020-01-01), 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 2,498 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 |
|---|---|---|---|
| Full poolused as 100% | 7,186.1 | 400,031 | detected from the record: 309 days at or above 7,186 ft and none above 7,187 in 52 years |
Capacity over time (2 tables in force)
| Period | Capacity (acre-feet) | How well supported |
|---|---|---|
| 1974-12-31 to 2011-12-311974-2011 table | 401,333 | Capacity recovered from the record, well supported |
| 2012-01-01 to 2026-11-02current table | 400,031 | The operator's current table fits the record |
Rivers
Data and sources
Record from 1974 (53 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: 18,935 days
Year by year (CSV) · Last 365 days (CSV)
Credit: Bureau of Reclamation HydroData; National Inventory of Dams (U.S. Army Corps of Engineers). Capacity analysis by New Mexico Water. Data accessed November 4, 2026.