Finally heeding a message of alarm that experts have been sounding for a decade, California voters in November authorized an unprecedented investment in the fragile network of levees that protects homes, farms and critical infrastructure in the Central Valley from catastrophic flooding. Between Proposition 1E, which authorized $4.1 billion for levee improvement, and Proposition 84, a water bond that included $800 million for flood-control projects, the levee system stands to get a $5 billion upgrade.

The investment comes not a moment too soon. Flood experts have long warned that California faces a potential disaster in the Central Valley, where 1,600 miles of levees protect about 400,000 people living in and around Sacramento, while another 1,100 miles of levees protect farmland, homes and critical infrastructure in the Sacramento-San Joaquin Delta.

Those experts have had trouble getting anyone to listen. But when the levees protecting New Orleans failed catastrophically in the wake of Hurricane Katrina in 2005, flooding 85% of the city and killing more than 1,000 people, the devastation finally focused public attention on the substandard condition of California’s flood system. The result: 64% of voters approved the levee improvement bond.

But apparently not everyone received the same message. Four days before the November election, an environmental group filed an appeal with the Delta Protection Commission to halt a large development planned in the Delta flood zone. Yolo County approved the project, proposed by Clarksburg Investment Partners LLC and 44 Willow Point LLC, on October 24, allowing construction of 162 homes on the old Delta Sugar mill property in Clarksburg, a small town on the bank of the Sacramento River. The plan also designates 25 acres for commercial use and 30 acres for industry.

“To put that many families directly in the floodplain is just indefensible,” said Kate Pool, a spokeswoman for the Natural Resources Defense Council, which filed the appeal. “Have we learned nothing about planning in lowlands since the disaster of Katrina?”

The Delta Protection Commission scheduled a January 25 hearing on the appeal, and told Yolo County to halt the project in the interim.

Like New Orleans, much of the Sacramento-San Joaquin Delta is below sea level and sinking. And like New Orleans, the bowl on the inland edge of San Francisco Bay is rimmed by a network of protective levees buffeted by storms and tides. There’s no big city in the Delta, but the levees there protect something critical to much of the state’s urban population: two huge pumping plants, one operated by the state and the other by the federal government. Located at the south end of the Delta, those pumping plants send water south in aqueducts to irrigate nearly 4 million acres of cropland in the San Joaquin Valley and to meet the residential and industrial needs of two-thirds of California’s population.

While the vulnerability of the Delta pumps has statewide significance, cities in the Central Valley outside the Delta are vulnerable to local flooding and rely on an aging system of protective devices that experts warn is inadequate. Judged by the level of protection provided by levees and dams, Sacramento faces the highest risk of flooding of any major American city, according to the Sacramento Area Flood Control Agency.

The Clarksburg development would be squarely in the valley’s danger zone, protected by flood-control levees. At issue in the NRDC appeal, which was filed on behalf of the group by Earthjustice attorneys, is whether the project site lies within the “primary zone of the Delta,” as defined by the Delta Protection Act. That legislation was adopted in 1992, designating primary and secondary zones in the Delta, establishing the Delta Protection Commission and requiring development of a land use and resource management plan for the primary zone (see CP&DR, June 2004).

That zone encompasses about 500,000 acres in the heart of the Delta. Because the primary zone is vulnerable to flooding and includes productive farmland and wildlife habitat, urban development is prohibited unless the proponents can demonstrate that their projects will not result in loss of wetlands or riparian habitat, won’t degrade water quality, won’t interfere with migratory birds or public access, won’t harm agricultural operations, and “will not expose the public to increased flood hazards.” The Delta secondary zone, consisting of about 238,000 acres, encompasses the remainder of the legally defined Delta region and has less stringent controls.

All local agencies whose jurisdictions overlap the Delta were required to amend their planning documents so they are consistent with the Delta Protection Act. Those include the counties of Yolo, Contra Costa, Sacramento, San Joaquin and Solano, as well as at least nine cities. Clarksburg is one of several unincorporated communities in the Delta, and the sugar mill development falls under Yolo County jurisdiction. The Delta commission arbitrates disputes over whether the actions of local agencies conflict with the Delta plan.

The mill was constructed in 1934 to process sugar beets and ceased operation in 1993. The current owners have transformed part of the brick mill complex into winemaking and tasting facilities, plus offices, shops and other commercial ventures.

Lawyers for Yolo County and the developer have argued that, although the site is technically within the Delta primary zone as shown on official state maps, the Delta Protection Act exempted previously developed areas from its restrictions on urban expansion.

In its appeal, the NRDC says the exemption was intended to apply only to property within city limits, and that the urban footprint of unincorporated Clarksburg does not count.

The larger issue at stake, according to the NRDC, is that the project would result in additional residents moving into a floodplain protected only by a century-old earthen levee that even the county acknowledges is likely to fail. Along with the 105-acre development, the project would include construction of a wastewater-treatment facility that also would be at risk of flooding.

The sugar mill project is only the second appeal the Delta Protection Commission has ever been asked to consider, which is somewhat remarkable given the pace of floodplain development in the Sacramento region over the past decade. Much of the growth, however, has taken place outside the Delta proper.

“While development in the primary zone has been moderate and consistent with the provisions of the management plan, activities in the secondary zone, have continued to increase at a significant rate,” the commission noted in its 2005 annual report. “Thus, the potential for development activities in the secondary zone to impact the primary zone continues to be of increasing concern.”

Documents related to the sugar mill project and the appeal, including filings by NRDC, Yolo County and the developers, are at