New Melones Dam

New Melones Dam is an earth and rock filled embankment dam on the Stanislaus River, about west of Jamestown, California, United States, on the border of Calaveras County and Tuolumne County. The water impounded by the dam forms New Melones Lake, California's fourth-largest reservoir, in the foothills of the Sierra Nevada east of the San Joaquin Valley. The dam serves mainly for irrigation water supply, and also provides hydropower generation, flood control, and recreation benefits.

The dam was authorized in 1944 as a unit of the federal Central Valley Project, a system designed to provide irrigation water to the fertile agricultural region of the Central Valley. It would be built by the U.S. Army Corps of Engineers (Corps), and transferred to the U.S. Bureau of Reclamation (Reclamation) upon completion. In 1966, work began to clear the foundations for a high dam that would replace an earlier, much smaller structure built by two irrigation districts. Construction of the main embankment began in 1976, and was topped out in late 1978. The filling of New Melones Lake began in 1978, and the dam's hydroelectric station produced its first power in mid-1979.

New Melones was the focus of a long environmental battle during the 1970s and early 1980s; critics protested the flooding of a long scenic stretch of the Stanislaus River, which flowed over whitewater rapids through the deepest limestone canyon in the western United States. The protestors employed a variety of methods, some extreme, to prevent the filling of New Melones Lake until 1983, when record-setting floods filled the reservoir and nearly breached the dam's emergency spillway. The fight over New Melones galvanized the river conservation movement in California and influenced major water policy changes on the state and federal levels; since its completion, no other dams of its size or importance have been built in the United States.

The New Melones project has continued to generate controversy, due to the water yield from the project being lower than expected, and the use of New Melones water to meet federal environmental standards at the expense of farming. The reservoir is considered "over-allocated"; in an average year, it is unable to meet all the demands placed on it. The debate over water rights continues today, with environmentalists seeking to further increase fishery flows, and the Stanislaus irrigation districts asserting their senior rights to the river.

Specifications

New Melones Dam and its reservoir comprise the independent New Melones Unit of the Central Valley Project. The dam's primary purpose is to control the runoff from , At high from the foundations and long, and containing of material, New Melones is the second tallest earthfill dam in the United States, after Oroville Dam, and the sixth tallest dam overall. During flooding events, the dam is operated to keep flows on the Stanislaus River below , although this figure may be lowered depending on flow conditions in the San Joaquin River. However, the Manteca Bulletin noted that the dam was operated carelessly during the 1997 flood – almost of farmland was flooded near the confluence of the Stanislaus and San Joaquin Rivers – and a further $80 million of damage could have been prevented had the reservoir been kept at a safe level. For the period 2001 to 2015, the plant produced an average of 418 million kilowatt hours (KWh) annually. About of land along the Stanislaus River are irrigated using water from New Melones. According to the Bureau of Reclamation, the increase in water supply from New Melones Dam has "translated into prosperity for the region, allowing the growth of cities including Tracy and Manteca, and irrigating high-value crops including almonds, walnuts and grapes." In addition, New Melones Lake is one of the major tourist draws of the region, providing activities such as boating, fishing and shoreline camping. An estimated 800,000 people visit the lake each year; however, droughts can cause the closure of lake facilities due to low water levels.

History

Background

thumb|right|The original Melones Dam

The modern development of the Stanislaus River began with the Oakdale and South San Joaquin Irrigation Districts, which were created in 1909 under the Wright Act to serve farmers in the area. Early irrigation along the Stanislaus River was dependent on the natural flow of the river, which was never enough to water crops during the late summer and fall. This reservoir was still not big enough for all the demands placed on it, especially during the long droughts of the 1930s.

The storage capacity of these early reservoirs was limited and the irrigation districts sought to increase the size of the Melones Reservoir. The federal Flood Control Act of 1944 authorized the U.S. Army Corps of Engineers to build a arch dam with a capacity of .

thumb|left|Map of the Stanislaus River watershed, showing today's major dams and reservoirs.

The Bureau of Reclamation first surveyed the Melones dam site in the 1950s, and initially supported the proposed 1.1 million acre foot reservoir but soon increased the size of the project (to be known as "New Melones II") twofold, as part of the Central Valley Project.

Although the 1944 version of the project had been abandoned, the Bureau and the Corps continued to argue over who would construct the dam.

Although the 1964 floods had initially generated support for New Melones, a spirited opposition to the dam arose from both the river recreation industry and environmentalists who saw the Stanislaus River canyon as having greater value than a reservoir. The river flowed through the deepest limestone canyon in the US, with cliffs rising above the water in places. Other natural features of the area included extensive limestone caves, and endemic species such as Banksula melones, the Melones cave harvestman. In addition, more than one hundred archaeological and historical sites, left over from Native American inhabitation and the Gold Rush period, were all situated in the reservoir flood zone.

While the US Army Corps of Engineers was constructing New Melones Dam, the dam operators, the US Bureau of Reclamation, applied to the California State Water Resources Control Board (SWRCB) for water rights for the project. During extensive hearings, the Environmental Defense Fund and the Sierra Club recommended that the SWRCB deny the Bureau’s applications for water rights because of the adverse effects of the project and the failure of the Bureau to show that the water sought to be stored will be put to beneficial use within a reasonable time. The Bureau took the position that the SWRCB was limited in its jurisdiction to determining if unappropriated water was available.

On April 4, 1973, the SWRCB issued Decision 1422 which held that the public interest requires the use of the Stanislaus River for whitewater boating, stream fishing and wildlife habitat be protected to the extent that water is not needed for other beneficial purposes. The SWRCB limited impoundment behind New Melones Dam to water needed for fish and wildlife releases, water quality releases, flood control and that needed to satisfy prior water rights at the existing Melones Reservoir. The Board reserved jurisdiction to consider allowing more storage behind New Melones Dam if the Bureau could show that the benefits from the storage outweigh the damage in the watershed above the dam and that the Bureau had firm commitments to deliver the water.

The federal government sued the SWRCB over the storage restrictions contained in Decision 1422. The federal government won at the district and appeals court level, but the US Supreme reversed the lower court decision. In 1978, the US Supreme Court held in California v. United States that under the 1902 Reclamation Act a State may impose any condition on control, appropriation, use or distribution of water in a federal reclamation project that is not inconsistent with clear congressional directives respecting the project. The Court remanded the case to the lower courts to consider the conditions imposed in Decision 1422.

While the administrative and legal battles were occurring, the environmental group Friends of the River (FOR) was formed in the early 1970s to push a statewide ballot measure, Proposition 17, which would have designated of the Stanislaus River between Stanislaus Powerhouse and Parrott's Ferry as a National Wild and Scenic River and stopped the construction of New Melones Dam. Development-related interests such as PG&E, the California Chamber of Commerce and the contractors working on the dam spent millions of dollars lobbying against Prop 17 (see images on the Stanislaus River Archive). One of their slogans, "Stop the 'Wild River' Hoax!" argued that this part of the Stanislaus River was not untouched wilderness (as dams already existed both upstream and downstream of the 9-mile segment) and therefore was ineligible for Wild and Scenic designation. This statement was misleading, since the language of the Wild and Scenic Rivers Act does not disqualify rivers with dams – only the portions already inundated by reservoirs. Dam supporters also argued that the Stanislaus River in its natural state was only accessible to a small group of people; that the rafting companies held a "monopoly" on river recreation and a reservoir would open up the area for far more tourists than would have visited otherwise, bringing more economic benefits to the area. Proposition 17 lost by a voter margin of 52.5%-47.5%.

Construction on the dam continued to progress. On April 1, 1978 the gates of the diversion tunnel were closed, and New Melones Lake began to fill, soon inundating the old Melones Dam. As the reservoir filled, work moved ahead on the power plant and generating units, which were all completed by the end of 1978. The main embankment of the dam was topped out on October 28, 1978. The Corps was delayed in handing the project over to the Bureau of Reclamation, as testing could not be completed on the hydroelectric turbines until the water level increased further. On May 29, Governor Brown vetoed Assembly Bill 2164, which would have allowed filling New Melones Lake to its full capacity. Further studies by the California Department of Fish and Wildlife and the Bureau of Reclamation itself showed that completely filling New Melones Lake would, in fact, offset some of the benefits of the project. For example, if additional water were provided for farms, even more water would have to be released into the Stanislaus River to wash out polluted return flows from new irrigation. A larger reservoir would also halt the Stanislaus' spring flooding to such an extent that it would harm the salmon populations that the dam was intended to benefit. Also, a higher reservoir would allow for less flood control space in emergencies. The state determined that the optimal reservoir volume was , which would provide enough water to fulfill existing rights and fishery flows as well as provide a hedge against droughts and floods; although it would inundate about of the river above Parrott's Ferry, FOR agreed to this compromise.

Ultimately, it was nature, not political maneuvering, that led to the filling of New Melones Lake. The winter and spring rainy season of 1982 was one of the wettest recorded in the 20th century. The Stanislaus River swelled to such high levels that it exceeded what could be safely released through the dam's outlets, and the reservoir rapidly surpassed the temporary limit. The winter of 1983 was even wetter and pushed water so high that it reached the lip of the emergency spillway (but did not flow over it), a level that has not been surpassed since. With the lake full, the state of California lifted the temporary limit in March, 1983.

Water rights disputes

thumb|right|Low water levels at New Melones, 2012

New Melones Dam has a very large storage capacity relative to the watershed that feeds it, as compared to other major reservoirs in California. The potential water yield, and thus the supply contracts, of the Melones Project were calculated based on stream flow data between 1922 and 1978; however, this period may have been somewhat wetter than the long-term average. Even so, the reservoir fell to a record low level of , 3.5% of capacity, on October 1, 1992. Conversely, the great storage capacity also means that New Melones can capture more flood runoff while other major California reservoirs must release it to maintain flood control space.

The original contracted water supply from New Melones Dam was , of which was allocated to the Oakdale and South San Joaquin Irrigation Districts (who owned the original Melones Dam and have the oldest water rights); for Stanislaus River water quality and fishery conservation; and for the Stockton East Water District. Originally, Reclamation had planned to extend the water supply to other users, but even from the start, the Melones Project was barely able to meet these existing targets. New Melones releases are important for regional groundwater recharge, a vital water source for farmers when surface water supplies are cut off due to drought, and to protect water quality in the Stanislaus and San Joaquin Rivers by diluting pollutants during the late summer and fall dry season.

Fishery flows

After the Central Valley Project Improvement Act in 1991 and the Bay-Delta Water Quality Control Plan in 1995, much more water was required to meet target environmental flows in the Stanislaus and San Joaquin Rivers and the Delta, which conflicts with the original language of the 1962 act authorizing the dam, which stated that only "excess water" could be appropriated for these uses. As a result, the Melones Project is now only able to meet all its contracts in above average water years. Local water users have coined the somewhat derisive nickname of "green dam" because the policy has shifted to favor fish rather than farmers.

thumb|left|A pair of [[Chinook salmon in the Stanislaus River]]

A further constraint is that water released in autumn must be cold enough for anadromous fish to survive, and thus must be made from the lower level outlets at New Melones Dam. However, the old Melones Dam was not demolished during the construction of the new dam (the original dam remains submerged far below the reservoir surface, only rarely re-emerging when the water level is low). The old dam partially blocks the movement of cold water from the deepest parts of the reservoir, causing warmer surface water to be drawn out instead. As a result, in certain years the amount of irrigation water has been reduced in order to maintain enough depth in New Melones Lake in the fall to preserve the cold water pool.

A 2016 study by independent environmental consulting group FishBio showed that the artificial spring pulse flows from New Melones Dam do fairly little to support salmon and steelhead out-migration in the Stanislaus River. Rather, the fish take their cues from increased water flow due to rainfall, as they naturally would have before the many dams on the Stanislaus River were built. In the spring of 2016 about 12,500 juvenile salmon migrated downriver to the sea during April and May, but less than 1 percent migrated during the pulse flow. In years of drought when the lake level is low, releasing water during the spring creates consequences later in the year – because there is not enough cold water left for the autumn spawning run. In addition, the minimum level of New Melones Lake would be set at (29 percent capacity) at all times in order to preserve the cold water pool. This would essentially limit the usable storage in the reservoir to the between the cold water pool and the flood-control pool, further handicapping the ability of the reservoir to manage water. Furthermore, it does not address other major problems including introduced striped bass in the San Joaquin River, which eat many if not most of the juvenile salmon and steelhead before they even reach the sea.

Conflict and compromise

In 2015, Congressman Tom McClintock introduced HR 1668, the "Save Our Water Act", which "amends the Endangered Species Act of 1973 (ESA) to suspend during droughts the application of the ESA to water releases from water storage facilities by federal and state agencies in a navigable river basin." McClintock specifically cited the release of from New Melones Lake over several weeks in spring 2015, when New Melones Lake was approaching its lowest level on record since the 1992 drought. That year, very few fish had returned to the Stanislaus to spawn; in an editorial for MyMotherLode, Mark Truppner wrote: "Biologists estimate that it will affect the offspring of about 29 steelhead trout in the Stanislaus River – a few hundred smolts [sic] almost all of which will be eaten by predators long before they reach the ocean. And that assumes they won't swim toward the ocean on their own – as they have been doing without our helpful assistance since time immemorial." However the bill did not pass. Previously, Reclamation had been taking the Stanislaus irrigation districts' water without paying for it. Essentially, the agreement allows for the water to be re-used for agriculture while still maintaining fishery flows in the Stanislaus River.

Legacy

The controversy over New Melones Dam was one of the most heated environmental disputes in the U.S. at the time. The Bureau of Reclamation itself has called New Melones "a case study of all that can go wrong with a project." Although opponents of the dam were ultimately unsuccessful, the campaign greatly strengthened the political power of the river conservation movement in California and the rest of the United States; in California, a number of later dam projects were defeated by citizen opposition, including a hydroelectric project on the nearby Tuolumne River which was canceled less than two years after New Melones Dam was completed.

thumb|right|320px|Aerial view of New Melones Dam (lower center) and Lake, looking northeast

In Dam Politics: Restoring America's Rivers, William R. Lowry writes:

The New Melones debate influenced the eventual protection of a number of other northern California rivers (the Eel, Klamath and others) under the National Wild and Scenic Rivers System starting in 1980. It considerably changed the California state government's approach to water resources development, switching focus from massive dam projects to conservation and policy improvements. In 1982, the same year that New Melones Lake filled, the Reclamation Reform Act set more stringent standards for vetting federal Reclamation projects, essentially "distancing federal policy from the 'dams-everywhere' approach of the past." However, the relative lack of new storage has severely strained California's water system, which now serves 15 million more people than it did when New Melones Dam was completed in 1979.

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In 1992 Congress passed the Central Valley Project Improvement Act, which dedicated of CVP waters to fish and wildlife conservation. During the drought in 1992 New Melones Lake was at a very low level; Friends of the River lobbied Congress to reinstate the original limit for lake level at the Parrott's Ferry Bridge. Larger releases would be made from New Melones Dam during spring flooding, helping to flush out salinity and pollutants in the river system and the Bay-Delta region. The loss of irrigation water would be mitigated with new conservation measures. Keeping the lake at a lower level would allow the restoration of of the Stanislaus River Canyon, once one of the most popular whitewater runs in the state, although the limited release capacity of the dam would still result in occasional flooding above Parrott's Ferry.-->In a history of the dam written in 1994 as part of the Bureau of Reclamation History Program, Joe Simonds came to this conclusion:<blockquote>The New Melones Dam stands as a reminder of the conflicts surrounding growth, the environment, and water in the West. The Corps built it at the end of the era of large dam construction. Even without the environmental controversy that surrounds the project, the operational and water yield problems will certainly cause continued difficulties well into the future. With the enormity of the problems facing New Melones, it seems unlikely that the project will ever realize its full potential as a multi use unit. Indeed, new Melones may become a case study of all that can go wrong with a project.</blockquote>

Notes

References

Works cited

External links

New Melones Dam
New Melones Power Plant
Post-Audit of New Melones Dam, by Kimra Dawn McAfee (Master's Thesis, May 2000)
Proposition 17
Stanislaus River Before New Melones Dam (1975 footage)
Station Meta Data: New Melones Dam (NML)
Stanislaus River Archive