Little Colorado River New Mexico

1. Basin Overview
The Little Colorado River (LCR) originates in the White Mountains of eastern Arizona but has a main tributary in Northwestern New Mexico called the Puerco River. The Puerco River has its headwaters at the Continental Divide east of Gallup. The River flows west-southwest through an area north of the Zuni Mountains generally paralleling I-40 and the Santa Fe Railroad tracks. It crosses the Arizona-New Mexico border near Lupton, Arizona and continues to flow for 88 miles before joining the LCR east of Holbrook Arizona. 17 Navajo Chapters are part of the LCR Puerco River Subbasin. In Northwestern New Mexico, the Basin covers 5,297 square miles.

2. Hydrology

The Puerco River mainstream is primarily ephemeral with a few stretches of perennial flow within the upper reaches of the Black Creek watershed. Black Creek drains a portion of AZ and NM and flows generally south from the eastern slopes of the Defiance Plateau, past Window Rock, into the Puerco River between Lupton and Sanders, Arizona. The United States Geological Survey (USGS) operates a Puerco River stream gauge 1 mile southwest of Chambers in Arizona. The maximum discharge recorded by this gauge between 1971 and 2009 was 17,800 cubic feet per second on Sept. 30, 1971, and the minimum discharge was often zero, from a drainage basin of 2,156 square miles. The average discharge for 2022 was 1,720 cubic feet per second.[1]

In July 1979, the largest single release of liquid radioactive waste in the United States occurred at the United Nuclear Corporation’s uranium mill near Church Rock, New Mexico. When the disposal pond was breached, most of the 94 million gallons of radioactive, acidic uranium tailings solution flowed into the North Fork of the Puerco River. Water quality is impacted by perennial dewatering effluent (Wastewater discharge from the removal of water of a perennial stream to access sub-surface areas. In this instance, the Puerco River was de-watered for the purpose of Uranium mining) and natural runoff. The water quality and level of contaminants in these waters is of greatest concern for stakeholders. These waters contain levels of radioactivity and certain toxic metals that approach or exceed standards and guidelines designed to protect the health of people, livestock and agricultural crops.[2]

The Navajo Nation identified a number of concerns regarding the Puerco River Watershed including; (1) Lack of a Comprehensive Watershed Plan, (2) Risk of flood damage to infrastructure, property, human health, (3) Sediment deposition/siltation, erosion, and sediment management issues throughout the watershed, (4) Water quality degradation and public safety risks, (5) Habitat impairments within the watershed, (6) Lack of adequate water supply and distribution infrastructure systems throughout the watershed.[3]

3. History Regarding Water Rights


In 2001, the federal government initiated a federal court action to determine the water rights of the Zuni Tribe after the state court general stream adjudication was dismissed for lack of prosecution by the State. Most of the Navajo lands within the Zuni River Basin include Ramah Chapter and some areas of Grazing District 16. In 2002, the Navajo Nation intervened in the adjudication. Two subproceedings within the adjudication address the Zuni and Navajo claims, and while both subproceedings are active, the Zuni claims will be litigated first. In 2012, the United States filed a Complaint and Statement of Claims on behalf of the Nation and in 2013, the Nation’s Supplemental Complaint was filed. Since 2017, New Mexico, Zuni, and Navajo parties have continued to develop a model capable of assessing impacts of proposed water uses to assist settlement and administrative initiatives.


4. Current Status: Litigation, Settlements, Etc.
The Nation is engaged in preliminary settlement negotiations with the United States, the Zuni Tribe, and the State of New Mexico, while an ongoing technical study of the hydrology of the Basin is being conducted.
On May 2, 2023, the Zuni Tribe and the State executed the Settlement Agreement to Quantify and Protect the Water Rights of the Zuni Indian Tribe in the Zuni River Basin and to Protect the Zuni Salt Lake. Ramah Land and Irrigation Company also signed a letter indicating no objection to the settlement. Zuni attorneys have continued to update the Tribal Council and staff for the Navajo Nation about the settlement process. Work continues on various settlement tasks, including preparation of federal legislation and other conditions precedent to enforceability of the agreement.

[1] USGS. (2009). Water-data report 2009 09396100 Puerco River near Chambers, AZ. USGS Water Data Report. https://wdr.water.
[2] Millard, J., Gallaher, B., Baggett, D., & Cary, S. (1983, Septem ber). The Church Rock Uranium Mill tailings spill: A health and environmental assessment. EPA Records Collection. https://sems
[3] U.S. Army Corps of Engineers. (2011, August). Navajo Nations- Little Colorado (Upper Puerco). Albuquerque District, U.S. Army Corps of Engineers. il-Works/Tribal-Program/NN-Little-Colorado/

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