Editor's note: This is the last in a four-part series.

For supporters of local water for locals, future opponents lie not to the south, but to the west.

Following in the footsteps of the federal Central Valley Project and California's State Water Project, which largely benefited the south of the state, is a third big idea for diverting water. It is the brain child of a string of agencies that fall roughly on an east-west line from Alpine County to Alameda County. It advances not a statewide diversion fate for all northern California water but rather a multi-regional diversion plan for Mokelumne River water. The idea arose in 2005 among the 16 members of a consortium called the Mokelumne River Forum. The forum is "made up primarily of water agencies and local governments with an interest in the Mokelumne River ... to discuss how to meet water management needs in the Sierra foothills, San Joaquin County and the East Bay while resolving long-standing water-rights disputes," its officials say.

East Bay Municipal Utility District director of water and natural resources Alex Coate said, "The disputes are generally about who should get the next increment of water from the river. "An example would be San Joaquin County's application for water rights from the Mokelumne."

The river forum's looming Inter-Regional Conjunctive Use Plan would allow EBMUD, for example, to take additional advantage of its Mokelumne River water allocation.

According to EBMUD, the IRCUP idea includes the following:

- An initial groundwater "recharge" phase that would pour Mokelumne River in wet years into the aquifer underlying San Joaquin County; in following dry years EBMUD could draw on that "water bank" to serve its coastal-area customers;

- Subsequent reservoir enlargement phases using existing reservoirs on the Mokelumne River and its upper tributaries; and

- A subsequent Duck Creek Reservoir construction phase if needed and supported.

Locally, Amador Water Agency will take part in fleshing out the plan.

"Other interested parties such as Foothill Conservancy, fishery organizations and other public members are anticipated to participate as stakeholders as the project is considered further," said AWA Interim General Manager Gene Mancebo.

The Foothill Conservancy's Pete Bell said, "We need to make sure that water planning for our counties is based on local residents' vision for our future, too."

EBMUD is largely silent on what the main IRCUP issues are - whether social, environmental, political, or otherwise.

"At this conceptual stage, it would be highly speculative to state what the main issues are that surround the development of the IRCUP," Coate said. "There will be a wide range of stakeholders interested in the IRCUP effort. It is difficult at this time to suggest who may be most affected and how, as the project is still conceptual. The concept has the general support of the Forum members (and) has generated discussion regarding potential environmental impacts. Given that it is just a concept it has no opposition at this time."

However, the concept includes a taller Pardee Dam, a taller Bear River Reservoir Dam and a new dam on Duck Creek in eastern San Joaquin County. Together these pieces would destroy recreation abilities, sacred American Indian ground and wildlife habitat, and have drawn opposition.

"IRCUP is the predictable result of the kind of project you get when you put a bunch of water engineers in the room and say "solve a water problem," Bell said. "They will almost always look at building expensive engineering solutions before less expensive, more environmentally sound solutions such as conservation and efficiency.The Duck Creek site is on one of the oldest California Department of Fish and Game conservation easements in the state - it includes important habitat for vernal pool species and other wildlife. The exercise of eminent domain proceedings on that land could harm the use of conservation easements as a conservation tool all over the state."

San Joaquin interests

The Northeastern San Joaquin County Groundwater Banking Authority is not a member of the river forum but still stands to benefit from substantial Mokelumne River water through the IRCUP.

"It's a difficult question to answer at this time (concerning water amount) because much of the project is in the conceptual phase, but suffice it to say, it would be in the hundreds to thousands of acre feet depending on the amount of wet-year flow," said Mel Lytle, agency resources coordinator.

That has raised opposition.

"There are no controls on groundwater pumping in the San Joaquin Valley," Bell said. "There may not be any water available to the foothill counties or East Bay from that 'water bank' in dry years. It's like putting money into a bank account from which anyone can write unlimited checks."

EBMUD, too, faults some of the San Joaquin Valley interests who would benefit from the IRCUP.

"San Joaquin County's MORE WATER Project alternatives ... propose to place a water intake tower directly in EBMUD's Pardee Reservoir, locate a conveyance tunnel and pipeline adjacent to EBMUD's Mokelumne Aqueducts and within EBMUD easements, and construct an additional river intake and conveyance pipeline downstream of EBMUD's Camanche Reservoir," Coate's memo to agency directors reads.. "(An environmental document assumes) ability to divert ... 46,000 acre-feet per year from the Mokelumne River through an intake placed below Camanche Reservoir, and 70,000 acre-feet per year through a Pardee Reservoir intake for a total Mokelumne and American River diversion up to 191,000 acre-feet per year ... ."