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Water Diversions Present River Risks, Report Says

Aerial view of the San Joaquin River in central California
The San Joaquin River in central California, long used to support agriculture, drinking-water needs, and hydropower, routinely loses much of its natural flow to diversions and is the most endangered river in the United States according to a new report. Sara Larsen

Water withdrawals pose the chief threat to several of the U.S. rivers identified recently as most at risk by the conservation organization American Rivers, of Washington, D.C.

May 6, 2014—Of the 10 most endangered U.S. rivers of 2014, two face threats associated with “excessive” water withdrawals, while two more are at risk from potential new water diversions, according to America’s Most Endangered Rivers 2014, the most recent version of the annual assessment from American Rivers, of Washington, D.C. Dams, outdated flood-management policies, polluted runoff, and industrial development comprise the main threats facing the remaining rivers that were included on this year’s list, which was released on April 9.

Topping the 2014 list is the San Joaquin River in central California. Long used to support agriculture, meet drinking-water needs, and generate hydropower, the San Joaquin River and its main tributaries have suffered in terms of impaired wildlife habitat and lost recreation opportunities. “Dams, levees, and excessive water diversions have hurt river habitat and opportunities for recreation and community access,” the report states. “Over 100 miles of the mainstem river have been dry for over 50 years, and water diversions along the tributaries take more than 70 percent of the natural flow.” As a result, the “river’s salmon and steelhead populations are on the brink of extinction,” according to the report. (Read “Is California Next?” in Civil Engineering, November 2005, pages 39-47 and 84-85.)

Three key factors complicate attempts to address these environmental problems. First, the San Joaquin and its tributaries provide drinking water to more than 4.5 million people. Second, hydroelectric facilities located along the waterways generate more than 3,000 MW of hydropower. Finally, water from the San Joaquin and its tributaries is used to irrigate immense swaths of arid farmland in California’s Central Valley, one of the world’s most productive agricultural areas.

“The San Joaquin River is ground zero for water supply challenges, but it is also fertile ground for new and innovative water supply solutions,” said Bob Irvin, the president of American Rivers, in an April 9 news release. “We want a future with a healthy river and sustainable agriculture. This ‘Most Endangered River’ listing is a call to action for all of us to come together around solutions to protect and restore reliable and predictable clean water supplies and a healthy river for future generations.”

To this end, American Rivers called on the State of California to ensure that the waterway has the flows necessary to meet the many demands placed upon it. A management plan for the San Joaquin River is currently being developed by the California State Water Resources Control Board and is expected to be released in July. The board “must act to increase flows in the river to protect water quality, fish, recreation, and community access, and support sustainable agriculture,” according to the report.

Another waterway that American Rivers said is at risk from diversions for agriculture is the Edisto River in South Carolina. The longest free-flowing blackwater river in the country, the Edisto is threatened by “lax state laws [that] enable excessive water withdrawals,” according to the report. For example, last year an agricultural interest was granted the right to withdraw up to 35 percent of the flow from the river’s South Fork during droughts. “This is an extremely large withdrawal for any river, and scientific studies have documented that fish and wildlife are adversely affected by far less severe flow alterations than those on the South Fork,” the report states. To prevent a similar situation in the future, South Carolina’s legislature and governor must amend a 2010 state water quality law “to protect the health and integrity of the state’s rivers, and to make it fair for all water uses—drinking water, industrial, and agricultural,” the report states.

Proposed water diversions also represent a potential threat to the Upper Colorado River basin in Colorado and the Gila River in New Mexico, according to the report. Eighty percent of Colorado’s precipitation falls on the Western Slope of the Rocky Mountains, mostly within the Upper Colorado River basin. However, 80 percent of the state’s population resides to the east of the Rockies in the area known as the Front Range, where communities have long relied on water supplies transferred west across the mountains. The dams and diversions used to effect such water transfers “decrease river flows, degrade the environment, and harm river recreation that is a key element for the tourism economy on the Western Slope,” according to the report.

Additional diversions have been proposed for certain waterways in the Upper Colorado River basin, prompting American Rivers to call on Colorado’s governor and Water Conservation Board to ensure that the Upper Colorado River basin is protected as part of a draft Colorado Water Plan that is under development and is scheduled to be released this December. Such protections should take the form of increasing water efficiency in cities and towns, modernizing agricultural practices so that they use less water, and avoiding new large-scale transmountain diversion projects, according to the report.

As for the Gila, New Mexico’s last free-flowing river, a proposed diversion and pipeline project could capture an average of 14,000 acre-ft/yr from the waterway for agricultural and urban uses. Such withdrawals would double the amount currently diverted from the river and “could severely impact the Gila’s unique ecological and recreational values,” according to the report. Rather than pursuing this approach, New Mexico should implement more sustainable, and affordable, solutions, American Rivers maintains. “Cost-effective solutions, such as municipal and agricultural conservation, effluent reuse, sustainable use of existing groundwater supplies, and watershed restoration could meet the region’s future water needs quicker, easier, and cheaper than a diversion and pipeline project,” the report states.

Existing dams pose problems for two waterways on this year’s list. Since 1892, the 68 ft tall, 275 ft wide Searsville Dam has stood on Sanfrancisquito Creek, a tributary of San Francisco Bay and one of the few that has not been converted into a concrete channel. In 1919, Stanford University acquired the concrete gravity dam, which impounds the Searsville Reservoir. Because it remains in a relatively natural condition, Sanfrancisquito Creek continues to provide habitat to steelhead trout, which is considered “threatened” under the Endangered Species Act. However, Searsville Dam blocks fish passage to 20 mi of upstream habitat, while also impairing water quality in the stream and contributing to flooding upstream of the structure, according to the report. One of several sources of nonpotable water that Stanford uses for irrigation and fire protection, Searsville Reservoir has lost more than 90 percent of its original capacity because of sedimentation.

At the Buckley Diversion Dam U.S. Army Corps of Engineers count the number of fish that pass from a trap to a fish ladder that will take them to a holding tank

At the Buckley Diversion Dam on the White River in Washington
State, employees of the U.S. Army Corps of Engineers count the
number of fish that pass from a trap to a fish ladder that will take
them to a holding tank. From there, the fish are transported by
and released upstream of Mud Mountain Dam.
Tanya M. King, U.S. Army Corps of Engineers, Seattle District

For its part, Stanford University is investigating alternatives pertaining to the dam and reservoir, including maintaining them as is, removing sediment to restore reservoir capacity, modifying the dam and reservoir to improve flood control, and removing the dam. The committee charged with conducting the investigation is expected to offer its recommendation to Stanford’s president and provost by year’s end, said Jean McGown, an assistant vice president and director of community relations for the university, in a written reply to questions posed by Civil Engineering online. From American Rivers’s point of view, dam removal is the best course of action. Because “feasible alternatives exist to replace Searsville’s water storage and water diversion functions,” the university “must select an alternative that removes the dam to restore this unique creek while protecting local residents from flooding,” the report states.

Fed by glaciers on Mount Rainier, the White River in Washington State offers habitat to four salmon species—Chinook, coho, chum, and pink—as well as steelhead and bull trout. Owned by the U.S. Army Corps of Engineers, the 430 ft tall Mud Mountain Dam prohibits upstream fish passage on the White River. Since the 1940s, the Corps has operated a facility for trapping fish attempting to pass upstream at the Buckley Diversion Dam, which was completed in 1912 and is located 5 mi downstream of Mud Mountain Dam. Fish trapped at the Buckley Diversion Dam are transported by truck and released upstream of Mud Mountain Dam. 

However, the aging fish trap at the Buckley Diversion Dam is unable to collect all the fish seeking to pass upstream, annually leaving thousands to an uncertain fate below the dam. Unfortunately, the dam’s outmoded fixed-weir design complicates efforts to operate the fish trap as effectively as possible, says Daniel Johnson, the operations program manager for the Mud Mountain and Howard A. Hanson dams at the Corps. Although the roughly 340 ft wide Buckley Diversion Dam has vertical flashboards that can be used to direct water to the fish trap, the process of adjusting the flashboards is difficult. “It’s challenging to make changes to the dam,” Johnson says. As a result, operators often have a hard time maintaining flow volumes in the trap that are most likely to attract fish. Meanwhile, significant increases in fish numbers during the past decade have at times simply exceeded the capacity of the trap.

Those fish that are collected face daunting conditions. “Even if salmon do make it into the overcrowded fish trap, they are often exhausted, delayed, impaled on rebar, and/or injured from the cramped holding facilities, which reduces their chances of survival after release,” according to the report. Calling for a “complete fix” of the Buckley Diversion Dam and fish trap by 2017, American Rivers estimated that both structures could be replaced for approximately $60 million.

Such a figure is likely low, Johnson contends. Three years ago, the Corp developed an $80-million plan to replace the dam and fish trap, a plan that had to be jettisoned following a “major change in budget climate” across the federal government, he says. The Corps now is developing an estimated $40-million plan to replace just the Buckley Diversion Dam. Designed with six gated openings that can be easily adjusted to accommodate varying flow volumes, the new dam would improve the performance of the existing fish trap, Johnson says. However, the new dam likely will not be completed and operational before 2022 at the earliest, he says.

The remaining endangered waterways cited by American Rivers were the middle stretch of the Mississippi River along Missouri, Illinois, and Kentucky, the White River in Colorado, the Haw River in North Carolina, and the Middle Fork of the Clearwater River and its tributary—the Lochsa River—in Idaho.



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