The valley’s heritage as an agricultural community and its history with quicksilver mining in the hills above Almaden Valley created environmental problems we live with today.

And no agency know this better than the Santa Clara Valley Water District. These were some of the issues on the table when the district invited residents to a meeting on Oct. 24. A particular focus of the session was the continuing effort to remove mercury from Almaden Lake, which borders the water district headquarters.

The water district didn’t start out to clean up waterways. It began because the Santa Clara Valley was sinking.

Decades before this area became Silicon Valley, it was home to major agricultural production that used groundwater for irrigation. By 1929, that overuse of water caused downtown San Jose to sink 14 feet, according to Beau Goldie, water district CEO.

That’s when local farmers and business leaders formed the Santa Clara Valley Water District. The public agency was charged with constructing reservoirs to recharge the groundwater basin and stop the valley from further sinking. After World War II, when the area’s population began exploding and demand for water increased significantly, the water district began importing water from other sources.

Today, it collects about 15 percent of the water we use from the Hetch Hetchy reservoir, 40 percent through delta water coming from the Sierra, about 30 percent from 10 Santa Clara County reservoirs, 5 percent from recycled water and 10 percent groundwater from wells.

The reservoirs perform a dual purpose, replenishing groundwater basins and providing flood protection. As residents increase water usage, the ground sinks; more flooding can occur during rainy months. Groundwater also must be replenished to keep salt water from the bay from intruding into the fresh water.

Today the water district has three main goals. It provides wholesale drinking water to 13 retail water suppliers in Santa Clara County, two of which–San Jose Water Company and Great Oaks Water Company–sell their water to San Jose residents. The district also provides flood protection for the county and is the steward of the area’s stream systems.

Because of droughts, the district has developed almost 20 different conservation programs. These offer incentives, including rebates, free device installations, one-on-one home visits, site surveys and educational outreach to reduce water usage by residents and businesses. The reservoirs release water during the dry summer months to ensure groundwater protection. The agency also has a water bank located outside of the county for dry time use.

The district owns three water treatment plants that can deliver nearly 220 million gallons a day of clean drinking water. These, according to the agency, meet or exceed all drinking water quality standards. A recent advance was replacing chlorine with ozone, an advanced technology for water purification.

The water district is constructing a plant to produce highly purified water to blend with existing recycled water for irrigation and industrial uses. In addition, it’s working with four Bay Area water agencies to determine the feasibility of constructing a regional desalinization plant using membrane filtration technology.

Since the early 1980s, the water district has invested more than $1 billion and protected more than 97,000 parcels from flooding, according to its annual report. “Our flood protection work is ongoing. We are working hard to remove the remaining parcels in the flood plane, including the upper Guadalupe River and Coyote Creek,” says Marty Grimes, supervising program administrator for district communications.

By 2016, under its natural flood protection program, the district will protect about 140,000 parcels, with about 55,000 left at risk to 1 percent flooding, Grimes adds.

“Long-range planning is critical for us to be able to use efficient resources,” says CEO Goldie. Among the district’s other plans are retrofitting the county’s dams to meet seismic standards, creating natural habitats in as many stream areas as possible and looking at innovative ways to advance water standards.

Measure B on this November’s ballot continues the water district’s tax of $54 per parcel that was passed in 2000 and will end in 2016. The renewed parcel tax would sunset in 2028.

Since state and federal funds are decreasing, the district must ensure adequate funding, according to Grimes. “We have projects in safe, clean water that are new, and our pipeline projects have a larger emphasis on the environmental process, among other projects that are costly. If we wait until the parcel tax expires [to ask voters to renew it], there could be a funding gap and it will be harder to pass.”