Measure S, placed on the ballot by the Marin Municipal Water District, is an ordinance calling for a public vote before the district approves construction or financing construction of the $105 million, 5-million gallon a day plant in San Rafael.
Measure T, proposed by opponents of the plant, is an ordinance that also calls for voter approval before the water district authorizes or starts construction of the plant, but it also prohibits the district from authorizing any planning or construction contracts or from appropriating any money, including bonds, for it.
Both measures require majority approval. Whichever measure receives the most votes in excess of 50 percent will pass.
If the water district's Measure S passes, district actions that are necessary before construction or financing the construction would not require voter approval.
If Measure T passes, the district would need subsequent approval by the majority of the voters before any money can be spent, including issuing bonds or implementing contracts for planning, engineering and construction of the desalination plant.
Opponents of Measure S include Sausalito vice mayor Linda Pfeifer, Fairfax vice mayor Larry Bragman, San Anselmo vice mayor Ford Greene and Fairfax Council member Pam Hartwell-Herrero.
They say Measure S will give the water district a blank check to spend what they believe will be $400 million, not $105 million, on the desalination plant.
Opponents of Measure S also argue the water district has already spent $4.5 million and plans to spend millions more on permits before construction begins. Only then would the district hold a public vote on whether to construct the plant, according to the opponents.
Measure S opponents favor Measure T and a public vote on the plant before more money is spent.
The Marin Municipal Water District and other supporters of Measure S say it allows the district to keep open its water supply options, including conservation and recycling, and allows the district to further study the plant as a future supply of potable water.
"It would be bad public policy, and risky to our water security, to forever deprive the community of any single potentially viable future water supply by forbidding the district from even analyzing or investigating any promising water option," supporters said in the county's election information pamphlet.
Measure S supporters say desalination can stabilize the water supply, provide drought protection and reduce pressure on streams and rivers that sustain fragile fish populations.
Measure S supporters include state Assemblyman Jared Huffman, Marin County supervisor Steve Kinsey, the Marin County League of Women Voters, Marin Conservation League and the Marin Municipal Water District.
In April, the district put the water desalination option on hold because of a 15 percent drop in water usage over the past three years.
In spring 2011, the district is scheduled to release its updated Urban Water Management Plan that will include projections of population and water demand during the next 20 years. The plan will guide future water supply options.
The district supplies water to 190,000 people in a 147-square-mile area in south and central Marin County.