… Los Vaqueros was a rare species, seemingly bred for threading the gauntlet of California water politics that’s held up other new storage projects for decades: It would have expanded an existing project, rather than starting from scratch, which meant fewer permitting hurdles. It would have gotten its funding from a pool of relatively deep-pocketed Bay Area water agencies, rather than politically precarious state or federal dollars. And it promised water for environmentally sensitive wetlands, helping it avoid lawsuits from environmental groups and tribes. But the expansion of the reservoir in the hills between the Central Valley and the Bay Area fell apart last month as the main water agency behind the project decided to back out, blaming high costs and lowered benefits as well as disagreement over who should pay for what. The breakdown has shaken Gov. Gavin Newsom’s administration, which has thrown its weight behind other big infrastructure proposals to store and move around more water — most notably Sites Reservoir in the Sacramento Valley and a tunnel underneath the crumbling Sacramento-San Joaquin Delta — as a way to adapt to climate change.