The Democratic leaders touted support for their $7.2 billion proposal from more than 20 business, agriculture and environmental groups with representatives seated around a table in the governor's office.
Absent were Republicans, whose support is necessary to replace the $11.1 billion water bond measure already on the November ballot.
"We're very close with a lot of compromise," Brown said. "This is a very balanced, integrated plan. It's not a grab bag."
The need for a water bond has been highlighted by the state's worst drought in a generation that is forcing farmers to fallow fields and local governments to mandate water restrictions.
Provisions in the latest bond proposal involving water recycling and groundwater cleanup could increase the availability of water during future droughts.
The bond also includes other water projects not directly related to supply such as ecosystem restoration and flood management.
Brown has been pushing for the less costly bond to minimize state debt. The latest proposal would authorize $7 billion in new borrowing and tap into $200 million in unused money for water contained in two previous ballot propositions.
GOP leaders say the Democrats' plan fails to provide enough money for new reservoirs. They are pushing for $500 million more in bond sales to provide funds they say are necessary for a reservoir in Colusa County and in the Sierra Nevada near Fresno.
"It does no good to only build half a dam," Senate Republican Leader Bob Huff said in a statement.
Some farmers, sport fishing groups and environmentalists in Northern California have criticized the Democrats' proposal as potentially enabling a tunnel project to divert water from the Sacramento River to Central Valley farmers and Southern California.
Sierra Club California Director Kathryn Phillips said tunnel contractors "could game the system so they take more water out of the delta than is healthy."
The bond language explicitly says the money cannot be used to pay for building the delta tunnels, which is favored by the governor, or addressing the environmental effects. Even so, opponents of the tunnel project point to provisions they say could fund projects associated with it.
Senate President Pro Tem Darrell Steinberg rejected that contention, saying a bond that is neutral on the tunnels should not contain language preventing such a project in the future.
"People can be for or against the tunnels," Steinberg said. "All we are saying here is the bond should be separate from that debate."
Steinberg would not say what concessions Democrats are offering to secure Republican votes, but he said the Democratic proposal provides a significant investment in water storage.
Replacing the current water bond on the general election ballot requires two-thirds votes in both houses of the Legislature. Democrats have a supermajority in the Assembly, but they need Republican votes to reach that threshold in the state Senate.
The Legislature has until Wednesday to approve a new bond measure for the ballot.