Since November, Clean Water Sonoma-Marin has sought to gather 11,000 signatures to put an item on the ballot requiring the Marin Municipal Water District to stop using fluoride in water until it could detail what’s in the chemical and report that to residents. It also wanted the district to provide a report showing that it is safe to ingest.

But the deadline was Monday, and the group had mustered only 8,500 signatures.

“I feel what we did is raise awareness,” said Dawna Gallagher-Stroeh, director of Clean Water Sonoma-Marin, who led the effort as she submitted signatures to election officials at the Civic Center. “The water district’s mission is to provide clean and safe drinking water. The public should have the right to know what’s in the water.”

The group had 180 days to gather signatures within the boundaries of the Marin Municipal district, which stretches from Sausalito to San Rafael. About 190,000 are served by the water district.

The group raised about $35,000 for the effort and had 200 volunteers collecting signatures, but Gallagher-Stroeh said myriad other local and state measures diluted the group’s effort to get the number of signatures needed to qualify.

For its part, the water district and its attorneys have said the agency is required to fluoridate.

“We are legally obligated to fluoridate our water and we have done that since 1973,” said Michael Ban, the environmental and engineering services manager for the water district.

Fluoridation at Marin Municipal began in December 1973 after 57 percent of voters gave approval in November 1972. Opponents failed to block it in court and in an appeal to the state Department of Health.

It was taken up again by voters in 1978 after water to five West Marin communities was accidentally overdosed with up to eight times the accepted level of fluoride for about two weeks in late 1977. In that vote, 53 percent of voters gave approval to continue fluoridation.

In 1995, Assembly Bill 733 was passed into law. The law requires public water systems that have more than 10,000 connections to provide fluoridated water as long as they don’t use ratepayer funds. The district receives about $1 million annually in rental income and uses about $140,000 of that for fluoridation.

The North Marin Water District, which provides water to Novato and West Marin, doesn’t fluoridate its water and does not fall under the rules of AB 733.

Last year, Marin Municipal lowered the amount of fluoride it puts into the drinking supply after the federal government said some children were getting too much, causing white splotches on their teeth.

It was the first change since the government urged cities to add fluoride to water supplies to prevent tooth decay more than 50 years ago.

Since 1962, the government has recommended a range of 0.7 milligrams per liter for warmer climates where people drink more water to 1.2 milligrams in cooler areas. The new standard is 0.7 milligrams everywhere and it was adopted by Marin Municipal as of May 1, 2015. Previously the district added 0.9 milligrams per liter of water.

The district said 0.9 milligrams is equivalent to one drop in 15 gallons, while the new standard is equivalent to one drop in 18 gallons.

Water board member Larry Bragman said he doesn’t think fluoridation is needed anymore, noting that fluoride is put in toothpaste, mouthwash and other dental products. But he said the district is bound legally to supply it, barring the voters overturning its use.

While he doesn’t believe ingesting fluoride is a health issue for the general public, he noted the district’s annual water quality report will provide more details about fluoride and include a cautionary statement about using fluoridated water for infant formula.

“I will keep advocating for the reduction and elimination of fluoride,” said Bragman, adding its use should be a personal choice.