Pecos River Compact Administration
Pecos River Compact accounting is completed for the preceding water year each spring. Compact accounting is completed using a complex methodology originally submitted in Texas v. New Mexico Supreme Court litigation as Texas Exhibit No. 108 in 1987. The methodology is incorporated in the Pecos River Master’s Manual.
Settlement Agreement Implementation
As part of achieving long-term compliance with the Pecos River Compact, the State of New Mexico reached an agreement with the Carlsbad Irrigation District, the U.S. Bureau of Reclamation and the Pecos Valley Artesian Conservation District regarding the adjudication of the Carlsbad Project Water Rights. While the agreement is complex and involves several issues, the hydrologic underpinning is the acquisition by the State of New Mexico of 18,000 acres of irrigated farmland and the utilization of water rights associated with those farmlands to augment the flows of the Pecos River through the construction of an augmentation well field with a minimum capacity to pump 15,750 acre-feet per year.
Acquisition of Land and Associated Water Rights
The New Mexico Interstate Stream Commission has so far purchased 804 acres within the Carlsbad Irrigation District and 2,994 acres within the Pecos Valley Artesian Conservancy District for a total of 3,798 acres. Work is in progress to acquire additional acreage needed to implement the settlement.
Augmentation Well Field Development
Augmentation well fields and pipelines are being developed in three locations: the Seven Rivers area, Hagerman Irrigation Company, and Lake Arthur. Four wells and a nested piezometer have been completed at Seven Rivers. A pipeline to deliver water from the Hagerman Irrigation Company canal to Rio Felix has been completed. A pipeline to deliver water to Pecos River from five wells in the Lake Arthur area is under construction.
Federal Issues Management
National Environmental Policy Act (NEPA)
The New Mexico Interstate Stream Commission is a joint lead agency in theCarlsbad Project Water Operations and Water Supply Conservation Environmental Impact Statement and Long-term Miscellaneous Purposes Contract Environmental Impact Statement.
There are many special status species found on or near the Pecos River. The Pecos bluntnose shiner and Interior least tern are federally threatened and endangered species. There are also four endangered invertebrates, Roswell springsnail, Koster’s springsnail, Noel’s amphipod, and Pecos assiminea, and one federally threatened plant species, the Pecos River Sunflower, that can also be found in the Pecos River basin.
Water Resource Planning, Development, and Investigations
Rio Hondo Channel Capacity Improvement
The Two Rivers Dam and Reservoir on the Rio Hondo, west of Roswell, New Mexico, was built in 1963 to protect the City of Roswell from the threat of severe flooding. The State of Texas objected to the construction of the Two Rivers Dam on the basis that it would reduce the flood inflows to the Pecos River and thus would reduce New Mexico’s delivery obligations to Texas under the Pecos River Compact. To eliminate those concerns, the City of Roswell agreed to maintain the existing channel capacity of the Rio Hondo at 1,000 cubic feet per second (cfs). In 1997, the State of Texas complained that the Rio Hondo channel capacity has not been maintained at the assured 1,000 cfs. In response to this complaint, a Joint Powers Agreement between the ISC, Chaves County, Chaves County Flood Commission and the City of Roswell to clarify the responsibilities of those parties in the channel capacity augmentation project was signed in October 2002. The parties to the JPA are working to improve the existing channel capacity on the Rio Hondo.
Phreatophyte Control
The Interstate Stream Commission is working as a co-lead agency with the Bureau of Reclamation in the Riparian Phreatophyte Evapotranspiration (ET) Monitoring Project. The purpose of the project is to conduct a salt cedar ET study in which ET will be measured by Eddy Covariance towers and remote sensing technology. The ISC, Reclamation, and the Carlsbad Soil and Water Conservation District are financial contributors to the project. New Mexico State University is providing scientific expertise and developing the research study design for the project.
The ISC also contributes $150,000 annually to the Bureau of Reclamation to fund continuous maintenance of cleared areas previously infested with salt cedar.
New Stream Gages
The ISC Pecos Bureau continues to improve monitoring and data collection on the Pecos River. The ISC installed a stream gage on the right bank of the Pecos River above the Nine Mile Draw, between Acme and Artesia, in September 2004. Two new gages, one above Brantley Lake and another above the Near Acme gage were also installed in 2005.
The ISC Pecos Bureau also recently received a grant from the Bureau of Reclamation to improve the Red Bluff gage near the New Mexico-Texas state line. The grant was part of Reclamation’s Water 2025 program and will work to improve the monitoring of water delivered to Texas.
Pecos River Decision Support System (PRDSS)
The PRDSS is a complex set of hydrologic models (Roswell Basin Groundwater Flow Model, Carlsbad Area Groundwater Flow Model, Pecos River RiverWare Model and A Water Accounting Model), model interfacing tools and pre- and post-processors. The PRDSS was developed over a period of years to allow decision makers to evaluate alternative water management scenarios in the Pecos River basin. The PRDSS has been used extensively for the Settlement Agreement and in the development of the EIS documents for NEPA (National Environmental Policy Act) compliance. Visit the Technical Reports page to learn more about hydrologic models applied to Pecos River basin issues.
