Editing Rio Grande (section)

==River modifications==
{{further|Rio Grande Project}}
The United States and Mexico share the water of the river under a series of agreements administered by the [[International Boundary and Water Commission]] (IBWC), US–Mexico. The most notable of these treaties were signed in 1906 and 1944.<ref>{{cite web |url = http://www.ibwc.state.gov/Treaties_Minutes/treaties.html |publisher = International Boundary and Water Commission |title = Treaties Between the U.S. and Mexico |archive-url = https://web.archive.org/web/20150601081248/http://www.ibwc.state.gov/Treaties_Minutes/treaties.html |archive-date=2015-06-01 }}</ref><ref>{{cite web |last = Thompson |first = Olivia N. |url = http://ecommons.txstate.edu/cgi/viewcontent.cgi?article=1315&context=arp |title = Binational Water Management: Perspectives of Local Texas Officials in the U.S.–Mexico Border Region |year = 2009 |work = Applied Research Projects |publisher = Texas State University |id = Paper 313 }}{{Specify|page number – the drainage+endorheic area does not appear to be in the paper|date=December 2010}}</ref> The IBWC traces its institutional roots to 1889, when the International Boundary Committee was established to maintain the border. The IBWC today also allocates river waters between the two nations and provides for flood control and water sanitation. Use of that water belonging to the United States is regulated by the [[Rio Grande Compact]], an interstate pact between Colorado, New Mexico, and Texas.

The [[Colorado River Compact|Upper Colorado River Basin Compact]] allots {{convert|62780|acre.ft}} of water from the upper [[Colorado River]] basin per year to municipalities in New Mexico. Albuquerque owns {{convert|48200|acre.ft}}, about three-quarters of the total amount. The water is delivered to the Rio Grande via the [[San Juan–Chama Project]]. The project's construction was initiated by legislation signed by President [[John F. Kennedy]] in 1962, and was completed in 1971. This diversion project transports water under the [[continental divide]] from tributaries of the San Juan River (the Navajo, the Little Navajo, and Blanco Rivers) to Heron Reservoir, which empties into the [[Rio Chama]] before this connects to the Rio Grande.<ref>{{Cite web |date=2012-09-25 |title=Project details - San Juan-Chama Project - Bureau of Reclamation |url=http://www.usbr.gov/projects/Project.jsp?proj_Name=San%20Juan-Chama%20Project |access-date=2024-09-03 |archive-url=https://web.archive.org/web/20120925123715/http://www.usbr.gov/projects/Project.jsp?proj_Name=San%20Juan-Chama%20Project |archive-date=2012-09-25 }}</ref> Although it held rights to San Juan-Chama water for many years, it was only as of 2008 that Albuquerque began using it as part of its municipal supply, with the completion of San Juan-Chama Drinking Water Project (SJCDWP) by the Albuquerque Bernalillo County Water Utility Authority.<ref>{{Cite web |last=Whitehead |first=Shannon |title=Your Drinking Water - San Juan Chama Project |url=https://www.abcwua.org/your-drinking-water-san-juan-chama-project/ |access-date=2024-09-03 |website=Albuquerque Bernalillo County Water Utility Authority |language=en-US}}</ref>

{{stack|[[File:1 Wtr Trtmnt Plnt A Cropped.jpg|thumb|Treatment plant, San Juan-Chama Drinking Water Project, Albuquerque.]]}}
The SJCDWP uses an adjustable-height diversion dam to skim imported San Juan-Chama water from the Rio Grande, then pumps this water to a treatment plant on Albuquerque's north side. From there it is added to a municipal drinking water distribution system serving Albuquerque's metro area. Diversions are restricted during periods of low river flow in order to protect the riparian ecosystem and mitigate effects on endangered species like the [[Rio Grande silvery minnow]]. [[Sewage treatment|Treated]] effluent water is recycled into the Rio Grande south of the city. Surface water from the SJCDWP comprises a significant percentage of Albuquerque's drinking water supply, with [[groundwater]] constituting the remainder; annual percentages vary according to runoff and climate conditions. Acquisition of native pre-1907 water rights is not part of the Water Authority's long-term resource management plan, dubbed WATER 2120.<ref>{{Cite web |date=2016-09-14 |title=Water 2120: Securing our Water Future |url=https://www.abcwua.org/wp-content/uploads/Your_Drinking_Water-PDFs/Water_2120_Volume_III.pdf |access-date=2024-09-03 |website=www.abcwua.org}}</ref>

Dams on the Rio Grande include [[Rio Grande Dam]], [[Cochiti Dam]], [[Elephant Butte Dam]], [[Caballo Dam]], [[Amistad Dam]], [[Falcon Dam]], [[Anzalduas Dam]], and [[Retamal Dam]]. In southern New Mexico and the upper portion of the Texas border segment, the river's [[Discharge (hydrology)|discharge]] dwindles. Diversions, mainly for agricultural irrigation, have increased the natural decrease in flow such that by the time the river reaches [[Presidio, Texas|Presidio]], little or no water is left. Below Presidio, the Rio Conchos restores the flow of water.<ref name=tsha/> Near Presidio, the river's discharge is frequently zero. Its average discharge is {{convert|178|cuft/s|m3/s|0}}, down from {{convert|945|cuft/s|m3/s|0}} at Elephant Butte Dam. Supplemented by other tributaries, the Rio Grande's discharge increases to its maximum annual average of {{convert|3504|cuft/s|m3/s|0}} near Rio Grande City. Large diversions for irrigation below Rio Grande City reduce the river's average flow to {{convert|889|cuft/s|m3/s|0}} at Brownsville and Matamoros.<ref name=ibwc/>