USGS to Develp Indicators to Better Measure Nation's H2O Supply: Greenwire

Home Browse Search

surface -water flow, land subsidence, and deteriorating water quality are beginning to occur. Agriculture in much of the area is heavily dependent on flow in the Rio Grande and Pecos River. Perhaps the most important factor governing flow in the Rio Grande is the Rio Grande Compact —an agreement between Colorado, New Mexico, Texas, and Mexico that attempts to allocate the water in the upper Rio Grande in a fair and impartial manner by explicit water - delivery requirements by the upstream State to the downstream State and Mexico. Since the Compact went into effect in 1939, there have been a number of years in which Colorado and New Mexico have been unable to meet their downstream obligations. In addition, the declaration of the Rio Grande silvery minnow and the southwestern willow flycatcher as endangered species has introduced new constraints on the management of water resources in the Rio Grande Region. Finally, the water rights of Pueblos in New Mexico have not been completely quantified. 14 Upper Colorado Region —The Upper Colorado Region includes portions of Arizona, Colorado, New Mexico, Utah, and Wyoming, with streamflow originating primarily from headwaters in Colorado, Utah, and Wyoming. Climate ranges from alpine in the headwaters to and in the downstream portions of the region. Most annual streamflow results from snowmelt during spring and early summer. Surface water provides the primary source of municipal and agricultural water. Most ground water used is from alluvial aquifers. Development of ground water associated with bedrock aquifers is limited. Water from the Upper Colorado Region is the primary source of streamflow in the Colorado River. The Colorado River Compact and the Upper Colorado River Basin Compact provides for the division and apportionment of the use of waters among the States in the Colorado River system. Water use and availability in the Upper Colorado Region has an important bearing on the administration of the Colorado River. In the last century, reservoirs, canals, and transbasin diversions were developed in the region to support agricultural, mining, and municipal water use. Some of the water stored in the upper portions of the region is sent through transbasin diversions to the Platte and Arkansas River Basins. Efforts to recover endangered fish are focused on providing more natural streamflow patterns. In the portions of the region experiencing rapid population growth, demand for the in- stream recreational use of water is increasing. In addition, conversion of water used for agriculture to urban and suburban use in these areas is raising questions about the effect these conversions may have on future water needs in the region and salinity and selenium loading in the Colorado River. Indian tribe reserve rights remain an important issue. 15 Lower Colorado Region - -The Lower Colorado Region includes most of Arizona and portions of California, Nevada, New Mexico, and Utah. In this and region, there is an urgent need for water- resources information due to rapid population growth, fragile ecosystems, and current drought stress. Water development (dams, canals and ground- water wells) has enabled an active demographic relocation to the only area of the United States in which consumptive use of water exceeds renewable supply. Many Lower Colorado River Basin communities, both large and small, depend on potentially unsustainable ground water for their water supply. A distinguishing characteristic of the region is the large proportion of reservoir storage compared to annual streamflow. Total 21