From email from the Bureau of Reclamation (Susan Novak Behery):
In response to decreasing flows in the critical habitat reach, the Bureau of Reclamation has scheduled an increase in the release from Navajo Dam from 500 cubic feet per second (cfs) to 600 cfs on Wednesday, April 21st, starting at 12:00 PM. Releases are made for the authorized purposes of the Navajo Unit, and to attempt to maintain a target base flow through the endangered fish critical habitat reach of the San Juan River (Farmington to Lake Powell).
The San Juan River Basin Recovery Implementation Program recommends a target base flow of between 500 cfs and 1,000 cfs through the critical habitat area. The target base flow is calculated as the weekly average of gaged flows throughout the critical habitat area from Farmington to Lake Powell.
Salinity levels in the Upper Colorado River Basin, which covers portions of Wyoming, Colorado, Utah, Arizona and New Mexico, have steadily decreased since 1929, according to a new U.S. Geological Survey study analyzing decades of water-quality measurements.
Salinity is the concentration of dissolved salt in water. High salinity levels in the Colorado River Basin cause an estimated $300-400 million per year in economic damages across U.S. agricultural, municipal and industrial sectors, as well as negatively impact municipal and agricultural users in Mexico. Reducing high salinity levels can benefit crop production, and decrease water treatment costs and damage to water supply infrastructure.
Findings indicate that large, widespread and sustained downward trends in salinity occurred over the last 50 to 90 years, with salinity levels decreasing by as much as 50% at some locations. The timing and amount of salinity reductions suggest that changes in land cover, land use and climate, in addition to salinity-control measures, substantially affect how dissolved salts find their way into streams that feed the basin.
“Identifying the causes of dropping salinity levels will be important for water managers in the basin so they can anticipate future changes in salinity and optimize salinity-control practices going forward,” said Christine Rumsey, USGS scientist and lead author of the study.
Results show the steepest rates of decline in salinity occurred from 1980 to 2000, coincident with the initiation of salinity-control efforts in the 1980s. However, there has been a consistent slowing of downward trends after 2000 even though salinity-control efforts continued. Significant decreases in salinity occurred as early as the 1940s in some streams, indicating that, in addition to salinity-control projects, other watershed factors are important drivers of salinity change.
“Having access to almost a century’s worth of salinity data provides greater insight to the water-quality changes that occurred prior to the implementation of salinity-control projects,” said Don Barnett, Executive Director of the Colorado River Basin Salinity Control Forum. “These findings are key in helping us understand the processes that cause and reduce salinity and assist us in our goal of protecting water quality in the Colorado River.”
Salinity occurs naturally in water due to weathering and the breaking down of minerals in soils and rock. The same process occurs in areas with irrigated agriculture, when irrigation water flows through soils and dissolves salts which eventually travel into streams. Irrigated areas contribute significantly more to stream salinity compared to areas without irrigated agriculture. Other factors known to affect salinity include geology, land cover, land-use practices, precipitation and climate.
“These findings indicate the issue of salinity in the Colorado River Basin is very complex,” said Rumsey. “Further work is needed to better understand the roles that climate change, land-use, reservoirs, population dynamics and irrigation practices play in salinity issues, which impact the economic well-being of the West and are important to U.S. relations with Mexico.”
Funding for this study was provided by the Colorado River Basin Salinity Control Program, the Bureau of Reclamation and the Bureau of Land Management. In 1974, Congress enacted the Colorado River Basin Salinity Control Act, which directed the Secretary of the Interior to proceed with a program to enhance and protect the quality of water available in the Colorado River for use in the U. S. and Republic of Mexico. The Colorado River Basin Salinity Control Program implements and manages programs to reduce salinity loads, investing millions of dollars per year in irrigation upgrades, canal projects and other mitigation strategies.
The USGS is the primary scientific agency for collecting data on water quality and flow in the nation’s rivers, with more than 13,500 real-time stream, lake and reservoir, precipitation and groundwater data stations across the country. The USGS also conducts analyses of these data to evaluate the status and trends of water-quality conditions.
The new study was published in the journal Water Resources Research.
Climate stresses are raising the stakes. Rising temperatures require farmers to use more water to grow the same amount of crops. Prolonged and severe droughts decrease available supplies. Wildfires are burning hotter and lasting longer. Fires bake the soil, reducing forests’ ability to hold water, increasing evaporation from barren land and compromising water supplies.
As a longtime observer of interstate water negotiations, I see a basic problem: In some cases, more water rights exist on paper than as wet water – even before factoring in shortages caused by climate change and other stresses. In my view, states should put at least as much effort into reducing water use as they do into litigation, because there are no guaranteed winners in water lawsuits.
Dry times in the West
The situation is most urgent in California and the Southwest, which currently face “extreme or exceptional” drought conditions. California’s reservoirs are half-empty at the end of the rainy season. The Sierra snowpack sits at 60% of normal. In March 2021, federal and state agencies that oversee California’s Central Valley Project and State Water Project – regional water systems that each cover hundreds of miles – issued “remarkably bleak warnings” about cutbacks to farmers’ water allocations.
The 1922 Colorado River Compact allocated 7.5 million acre-feet (one acre-foot is roughly 325,000 gallons) to California, Nevada and Arizona, and another 7.5 million acre-feet to Utah, Wyoming, Colorado and New Mexico. A treaty with Mexico secured that country 1.5 million acre-feet, for a total of 16.5 million acre-feet. However, estimates based on tree ring analysis have determined that the actual yearly flow of the river over the last 1,200 years is roughly 14.6 million acre-feet.
The inevitable train wreck has not yet happened, for two reasons. First, Lakes Mead and Powell – the two largest reservoirs on the Colorado – can hold a combined 56 million acre-feet, roughly four times the river’s annual flow.
Second, the Upper Basin states – Utah, Wyoming, Colorado and New Mexico – have never used their full allotment. Now, however, they want to use more water. Wyoming has several new dams on the drawing board. So does Colorado, which is also planning a new diversion from the headwaters of the Colorado River to Denver and other cities on the Rocky Mountains’ east slope.
Truth be told, that’s not a lot of water, and it would not exceed Utah’s unused allocation from the Colorado River. But the six other Colorado River Basin states have protested as though St. George were asking for their firstborn child.
Utah blinked. Having earlier insisted on an expedited pipeline review, the state asked federal officials on Sept. 24, 2020 to delay a decision. But Utah has not given up: In March 2021, Gov. Spencer Cox signed a bill creating a Colorado River Authority of Utah, armed with a US$9 million legal defense fund, to protect Utah’s share of Colorado River water. One observer predicted “huge, huge litigation.”
Before Utah takes the precipitous step of appealing to the Supreme Court under the court’s original jurisdiction over disputes between states, it might explore other solutions. Water conservation and reuse make obvious sense in St. George, where per-person water consumption is among the nation’s highest.
St. George could emulate its neighbor, Las Vegas, which has paid residents up to $3 per square foot to rip out lawns and replace them with native desert landscaping. In April 2021 Las Vegas went further, asking the Nevada Legislature to outlaw ornamental grass.
The Southern Nevada Water Authority estimates that the Las Vegas metropolitan area has eight square miles of “nonfunctional turf” – grass that no one ever walks on except the person who cuts it. Removing it would reduce the region’s water consumption by 15%.
Water rights litigation is fraught with uncertainty. Just ask Florida, which thought it had a strong case that Georgia’s water diversions from the Apalachicola-Chattahoochee-Flint River Basin were harming its oyster fishery downstream.
That case extended over 20 years before the U.S. Supreme Court ended the final chapter in April 2021. The court used a procedural rule that places the burden on plaintiffs to provide “clear and convincing evidence.” Florida failed to convince the court, and walked away with nothing.