A Landscape Long Under Pressure
The delta’s waterways are a brackish mix of mostly fresh water and some salt water from the Pacific Ocean. Plans have been in the works for years to build a massive new water diversion facility and tunnels under the Delta (the environmentally destructive California WaterFix project) and to increase water diversions, reducing freshwater flows into and through the estuary. Even though water exports from the Delta by the state and federal water projects only account for approximately 8 percent of the state’s total water supply, nearly two thirds of the state’s population and one third of California’s irrigated farmland rely in part on water from the Bay-Delta.
The delta sits largely below sea level, and the lands and islands that border the rivers are protected by a system of levees (shown top right, below). The levees were built in the mid-1800s, mostly by Chinese laborers who helped cultivate the region. Before this, the area where the delta now sits was mostly tidal marsh. Age has taken a toll. In 2004, a 350-foot section of a levee collapsed, flooding more than 5,000 acres of crops and homes in the Upper Jones Tract. This sounded an alarm, prompting state and local agencies to spend tens of millions of dollars maintaining and upgrading levees in the Delta.
In early 2017, after weeks of heavy rains in Northern California, levee workers intentionally breached a section along the Mokelumne River. This flooded the McCormack-Williamson Tract, an island of farmland near Walnut Grove (shown bottom left, below) that has been owned by the Nature Conservancy since 1999. The organization has sought to restore the area’s tidal freshwater marsh and floodplain habitat.
Farming the Delta
A majority of land in the delta is dedicated to farming, and agriculture is the economic engine of the region. Crops such as rice, grapes, berries, pears, and almonds are grown year-round, providing jobs to thousands of local and seasonal workers.
Climate and soil in the delta make it one of the most productive growing regions in the state. However, the tilling of the peat-rich soil is a major source of carbon emissions. State and local agencies, in partnership with a coalition of environmental groups and other stakeholders, are working to restore portions of its wetland ecosystem as a critical tool in the fight against climate change.
Farmers in the Delta have easy access to water from nearby irrigation pumps, but there remain disputes over water rights in the Delta, as there are in many parts of California. A 2014 study concluded that California has issued water rights for five times more water than exists in a normal year in California.