Flood-Control Channel Tamed an Unruly River

The San Diego River has always been a temperamental neighbor.

Before construction of the existing flood-control channel that empties into the Pacific Ocean near Mission Bay, the San Diego River generally ran wherever it wanted during the rainy months. Until a flood-control channel was created in the late 1800s, the river often ran through to San Diego Bay.

Planning experts now agree that it is unwise to allow heavy development in flood basins. But the first massive wave of commercial, residential and industrial developments had sealed the fate of Mission Valley by the early 1960s. The valley will grow even more congested during the next 20 years as land is freed from the threat of flooding.

“You can’t go back to where it was” 30 years ago, said San Diego City Architect Mike Stepner. “It would have become a heavily traveled (area) with or without Mission Valley development.”

The development allowed in the past amounted to “piecemeal destruction” of the river’s natural habitat, according to Jack Fancher, a biologist with the U.S. Fish & Wildlife Service’s Laguna Niguel field office. With additional development of the flood plain already approved, there are “very few options” left which will retain the valley’s remaining native habitat, according to Bill Tippets, a state parks resource ecologist.

Given other options--a concrete riverbed or a grass-lined ditch--the First San Diego River Improvement Project, with its natural habitat presented a “fascinating” alternative, Stepner said. “We managed to turn it around” and make the river “something that all San Diegans can make use of,” Stepner said.

Biologists and naturalists will continue to debate whether the restoration project is a success. And experts will continue to debate the wisdom of allowing more development in the valley.

Philip Pryde, a San Diego State University geography professor, is satisfied with what FSDRIP looks like. But, from “a geography standpoint, I don’t like it, because it’s not adequate,” Pryde said.

“Sooner or later, its capacity will be exceeded,” Pryde said. “It’s like saying sooner or later there will be an 8-point earthquake on the San Andreas Fault.”

Howard Chang, an SDSU engineering professor who designed the channel, acknowledged that, in time, the FSDRIP channel will overflow. But designing a flood-control channel for a 200-year flood is “not justified because the useful life span of a building is 100 years,” Chang said. “If it does flood, only the first floor of the buildings will be flooded, and I don’t mind changing the carpets every 100 or 200 years.”