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When it comes to California and climate change, the predictions are staggering: coastal airports besieged by floodwaters, entire beaches disappearing as sea levels rise. Another disturbing scenario is brewing inland, in the sleepy backwaters of the Sacramento-San Joaquin Delta. It’s a threat to the Delta’s ecosystem that could swallow up a significant portion of California’s water supply. Scientists from government and academia say rising sea levels caused by climate change will bring more salt water into the Delta, the hub of California’s water-delivery network.

Kicking off what are expected to be years of legal battles, a coalition of environmental and fishing groups on Thursday filed the first major lawsuits over California Gov. Jerry Brown’s $17 billion plan to build two massive, 35-mile-long tunnels under the Delta to make it easier to move water from Northern California to the south. The Natural Resources Defense Council, Defenders of Wildlife, Bay Institute and Golden Gate Salmon Association filed two lawsuits in U.S District Court in San Francisco.

Brett Baker is a sixth-generation pear farmer on Sutter Island in California’s Sacramento-San Joaquin Delta. His orchards are surrounded by levees, and water from the Sacramento River regularly percolates inward and upward through the soil. “We actually have to pump out water that creeps through our levees back into the river – we have to fight to keep groundwater levels down,” Baker says.

Drought and over-allocation are a persistent threat to the Colorado River’s water supply, the source of much of Southern Arizona’s water, and “water banking” is one way managers work to buffer the state against shortages. The method of storing water underground in natural aquifers for future use has been a crucial component of Arizona’s water management plan for more than three decades. And the practice raises questions about how and where water is stored, who owns stored water, how much can be recovered, and when and where can it be recovered.

Facing a crisis after a huge crater formed in the main flood-control spillway at Oroville Dam, officials at the California Department of Water Resources called in an old hand to help: David Gutierrez, a nationally known engineer who had just retired as chief of the agency’s dam-safety division. He seemed like an obvious choice for dealing with an emergency at America’s tallest dam – valued for his technical expertise, his coast-to-coast connections in the engineering field, and his years of experience.