The U.S. Bureau of Reclamation will release more than 4 billion gallons of water from New Melones Reservoir into the Stanislaus River over the next couple of weeks for "pulse flows" intended to push salmon smolts out to sea.

Bureau spokeswoman Erin Curtis said the releases will reduce the amount of water stored in New Melones by about 15,000 acre-feet. For perspective, the amount of water that will be released could serve roughly 40,000 Tuolumne County residents for an entire year.

The spring pulse flows typically occur in April each year, Curtis said, but the bureau was approached by the National Marine Fisheries Service and California Fish and Wildlife Service last week about releasing the water earlier due to abnormally warm water temperatures for this time of year.

"We have to operate the CVP (Central Valley Project) in real-time based on the conditions at the moment," Curtis said. "What we know is that we can make these releases now and still meet our delivery obligations later in the summer."

The pulses started ramping up about 1 a.m. Wednesday, and will slowly be reduced until the flows return to normal by April 2.

According to Curtis, the idea is to push the smolts into the Delta earlier because the river temperatures will likely warm to lethal levels prior to normal pulse flows in April.

"The goal isn't to cool the river, but rather to move the smolts out of the river," she said. "If they stayed any longer, they would die."

Critics argue the pulse flows waste water that could otherwise be saved for human use as California limps through a fourth year of drought.

Congressman Tom McClintock, R-Roseville, recently lobbied the bureau and federal regulators to modify their operations so that more water could be held back in New Melones and Tulloch reservoirs over summer to meet the demands of residential users and agriculture.

The early pulse flows are part of an agreement struck this week between federal agencies and the Oakdale and South San Joaquin irrigation districts to operate New Melones in a way that would allow more water to be held back over the summer in the Tri-Dam Project's Tulloch Reservoir, which also serves as the main drinking-water supply for about 5,000 residents near Copperopolis.

The entire modified operations plan, however, is still awaiting approval from the State Water Resources Control Board before all the steps can move forward.

"This whole operation is part of a suite of actions that are incorporated into our temporary urgency change petition being submitted to the State Water Resources Control Board," she said.

Curtis said the idea of nixing the normal April pulse flows out of New Melones and releasing 15,000 acre-feet of water this early was to meet the requirements of a 2009 federal biological opinion that ultimately dictates the reservoir's operations, without the risk of having to release even more water than normal next month due to the warmer temperatures.

"We could achieve what we needed to achieve with the least amount of water required," she said. "It made sense from an operational standpoint."

Still, some are critical of doing the pulse flows at all during the fourth year of an ongoing drought.

Copperopolis homeowners near Tulloch Reservoir were worried that a projected lack of water in New Melones would lead to the draining of Tulloch by July or August, which could hurt property values and area businesses dependent on summer tourism.

"It really is appalling the federal government is going to continue doing these things in the middle of a drought," said Jack Cox, leader of the Lake Tulloch Alliance, an advocacy group for Tulloch-area homeowners.

"The purpose of these reservoirs was to store water and be able to do flood control," he added. "They were never intended for fisheries issues or to deal with environmental problems in the Delta."

The alliance will host a public forum about the water crisis at 10 a.m. Saturday at Black Creek Park in Copperopolis. McClintock and Assemblyman Frank Bigelow, R-O'Neals, are expected to attend, along with other state and federal representatives.