Cambria services district directors have winnowed down a plausible range of alternative water sources for the town, but have left themselves the option of adding one or two more projects to the list when they meet again at 12:30 p.m. Thursday, Aug. 23.

Three of the five directors tentatively reduced the eventual project’s anticipated water volume to 250 acre feet a year from 400, which was the amount studied by consultants to the Army Corps of Engineers. The Corps is the Cambria Community Services District’s partner in using an allocated $10.3 million in federal funding to find a site for and build a desalination plant to provide the town with additional fresh water.

The vote Aug. 9 was 3-0, with Board President Allan MacKinnon absent, and Director Mike Thompson having left the workshop meeting before Director Jim Bahringer made his motion.

An acre foot is 325,900 gallons, which according to district officials is approximately enough to supply four Cambria homes for one year, assuming 2.21 persons per occupied home.

The next meeting is to be-

gin at 12:30 p.m. Thursday, Aug. 23, at the Veterans Memorial Building, 1000 Main St. Directors then could add other projects to the final cut, including such options as an aggressive program of increased water-conservation, reuse or water-demand management.

The district has been studying desalination and other project options for more than two decades, to compensate for periodic shortages of water, usually caused by lack of rainfall and drought.

The water projects that made the cut Aug. 9, and which are to be studied in depth for federal and state-level reports about potential environmental impacts, were:

•Two possibilities involving Whale Rock Reservoir, one plan in which excess winter water from San Simeon and Santa Rosa creek basins is pumped to and stored in the reservoir, then drawn back to Cambria during the dry season, and another a three-way exchange in which rights to or payment for Lake Nacimiento water would go to San Luis Obispo in exchange for an equal volume of water from Whale Rock reservoir. Army Corps of Engineers consultants’ rough estimates of the costs to build those options would be more than $30 and $40 million, respectively, with a per-acre-foot water cost of $5,250 and $7,250.

• A plan to filter salt out of brackish water (a blend of creek and sea water) drawn from three wells near the district’s well field along San Simeon Creek. While some of the details are still being hammered out, the water would be treated in a reverse-osmosis and advanced water-treatment plant. The purified water could be pumped upstream and into the creek, where it would migrate downstream and recharge the creek lagoon with fresh water during the dry season, fulfilling requirements that currently impact the supply of water available to the community. The briny leftovers, which probably would be less salty than seawater, could be pumped to a site on or near the Caltrans Highway 1 right of way or another site, where they’d be diffused by water in the aquifer and flow into the ocean. The consultants’ rough estimate for that San Simeon Creek Road Brackish Water project is nearly $17.9 million.

• Doing no project at all, an option that the National Environmental Protection Act and California Environmental Quality Act would require to be studied alongside the proposed projects.