Folsom’s plan to annex 3,600 acres south of town depends on finding water – hundreds of thousands of gallons of it per year.

The city last month hired the RMC Water and Environment firm of Rancho Cordova for a range of tasks including consulting with a trio of water agencies. Officials want to secure rights to a total of 10,000 acre-feet per year of Sacramento River water controlled by Natomas Central Mutual Water Co. of Rio Linda. An acre-foot is 325,851 gallons.

“The city has tentatively identified the Freeport Regional Water Project as the potential diversion point off of the Sacramento River to convey water to the Folsom sphere of influence,” wrote Ken Payne, utilities director, in a report to City Council members.

Payne said terms of the Water Forum Agreement of 2000 prevent diversion of American River water for development south of U.S. Highway 50, Folsom’s current southern border. Parties to the agreement were representatives of developers and builder organizations, environmental groups, landowners and governments. Terms are designed at once to assure water for development and protection of the American River from over-exploitation.

Sacramento River water is the only practical candidate, Payne said.

Under a still-to-come agreement now two years into negotiations, water now going to irrigate rice fields would gradually be reassigned, as development occurs, to Folsom, Payne said.

“It’ll phase itself in,” he said.

Water would come from a pump plant on the Sacramento River at the Freeport Bend, upstream of the town of Freeport and about 10 miles south of downtown Sacramento, according to the Freeport Regional Water Authority Web site. The authority is a joint venture of the Sacramento County Water Agency and the East Bay Municipal Utilities District.

Payne and City Councilwoman Kerri Howell said Folsom won’t “dry up” any current Sacramento River water user to gain the water right it seeks.

“Nobody’s taking a giant hit,” Howell said. “Natomas is moving from agriculture to residential.”

Some major landowners in the proposed annex are business entities associated with developer Angelo Tsakopoulos, city documents show.

Dee Swearingen, general manager of Natomas Central Mutual Water Co., referred questions to Mike McDougall of area landowner South Folsom Investors LLC and MJM Properties, a company hired by Tsakopoulos’ AKT Development to handle some of its land. McDougall could not be reached for comment.

RMC Water and Environment officials referred questions to the city of Folsom.

Area landowners and developers will bear the cost both of the consultant contract and the city expense to acquire and move water to the proposed annex. That meets terms of voter-approved Measure W, which said ratepayers won’t bear cost to acquire water for city expansion.

“This is easy on paper but expensive,” Payne said. “The landowners recognize that.”

Bob Holderness of landowner Russell-Promontory LLC said the Freeport authority’s pump will get water close to Folsom’s sphere of influence.

“We’re going to be able to hitchhike -- we don’t have to build a whole new system,” Holderness said. “We’ll pay our own freight up to the Folsom SOI.”

Users will pay a rate higher than in other areas of Folsom, Holderness said.