Prop 1 passed by a healthy margin. It's $7.5 billion, not $14 billion as stated in an early post. $2.7 billion for water storage, but the way its written, don't worry this will lead to a lot of new dams. It specifically won't pay directly for water supply storage. The wording separates "public benefit" from "private benefit" and only funds the costs of a project relative to the "public benefits." And no more than 50% of any project. So this is a cost-sharing arrangement that will not fund any project in its entirety.
Strangely, water supply is not considered a "public benefit" by this proposition. Whatever part of a dam or project that is allocated for water supply, that cost has to be paid for by the end user, even if they are a public agency like a city. I find that an odd distinction, but I get the concept. If you want the water, you have to pay to develop the storage. The state will pay for costs associated with environmental benefits, recreation benefits, flood control control benefits, groundwater recharging benefits, but not for new surface water supply. So this will help get water infrastructure projects going, but it won't pay for developing more water supply directly. Theoretically, the entire $2.7 billion could go for dry flood control dams and environmental habitat without actually increasing water supply one drop. I don't think it will happen that way, but it illustrates the way this is prop is worded.
The end result will probably be a lot more groundwater recharge, maybe one large new dam, and likely some smaller dams will be built or raised. The other funds (besides the $2.7 billion for water storage) will help with water conservation, groundwater monitoring, fixing leaky pipelines, and other water projects that will help conserve or clean up existing supplies.
So overall, Prop 1 will help, but don't worry about too much money going for new dams. It's just a drop in the bucket, a bucket that people don't appreciate until its empty.