While there's widespread support for Measure AA, there also is opposition.
Measure AA parcel tax amounts to $12 a year or $1 per month for the next 20 years.
The $25 million raised each year would go to a wide range of projects to protect the body of water that gives the region its identity.
"It's about protecting the Bay from harmful pollutants, toxic materials, trash. It's also helping to address the flood risk we all face," said Mike Mielke, with the Silicon valley Leadership Group.
Flooding is something Bay Area residents have already experienced during king tide events in Marin and along San Francisco's Embarcadero.
Billboards along the Bayshore Freeway warn that areas east of Highway 101 are vulnerable to floods.
A map of the South Bay names the Silicon Valley tech giants that could be underwater from flooding and rising sea level. Dozens of business, environmental and labor organizations are supporting Measure AA.
However, opponents of Measure AA believe there's little benefit for North and East Bay taxpayers.
"Based on what we've been able to calculate, those counties that will not receive a fair portion of the benefits will be paying a much higher portion of the actual tax revenues," explained Jack Weir, President of the Contra Costa Tax Payers Association.
Supporters argue the benefits are region-wide.
"Even though you may not see it day-to-day, you're glad knowing it's there. It's always a resource there for you to enjoy, to go swimming, to do other outdoor recreation activities, to fish, to use the Bay trail," said Mielke.
"It's just a very regressive, very unfair, and a very bad tax measure," said Weir.
A two-thirds vote is required for passage.