Messing with Pasadena’s Devil’s Gate

Disaster is often more foreseeable than we think. Remember the warnings for years before Hurricane Katrina that the New Orleans levees were in dire need of renovation? In that case, as in many others, top officials were given the information they needed, but they put off doing anything about it.

The echoes of such tragedies should be ringing in the ears of Los Angeles County supervisors who have kept the Department of Public Works from clearing out the mud-choked basin above Devil’s Gate Dam in Pasadena. According to a report by the agency, 1 million cubic yards of sediment filled the basin during the winter storms after the 2009 Station fire. That’s 10 times the volume of debris deposited in the reservoir during all of the 16 years before those storms.

The sediment has buried one of the dam’s outlet gates and threatens to block others, the report says. And that’s not the big threat: The basin is simply too full to hold another major flow. Should that happen, there could be catastrophic flooding and mudflows into South Pasadena and northeast Los Angeles.

Yet, as Times staff writer Rong-Gong Lin II reported this week, the Board of Supervisors hasn’t given the go-ahead to clear out the basin, instead allowing small-scale interim measures while the county begins environmental impact studies that could take a couple of years. That’s despite warnings from Public Works that these interim measures will fall short if there is a similar winter of massive debris flow.

A majority on the board has raised concerns about digging out the willow trees that have sprung up in the basin, providing habitat for birds and other wildlife. The site has provided a welcome bit of nature for hikers. And the 300 to 400 trips made each day by dump trucks until the task is finished would undoubtedly be a nuisance to local residents.

All true, but the dam and reservoir behind it were built to provide public safety, not a jogging area. The supervisors understandably would like to see if both are possible at Devil’s Gate, just as deep-sea oil rigs also can serve as reefs for marine life. But no one knows if they will have the time to get an answer; they’re playing roulette with nature.

There might be ways to forge a reasonable compromise — by, say, authorizing a large-scale cleanup of the basin but leaving some portion of it untouched. If the supervisors want to pursue that route, they should take their guidance from Public Works about how much debris removal is necessary to ensure public safety. They have received clear warning from the experts in this matter that the current interim measures won’t do the job if there is catastrophic runoff. Delay is dangerous, and protecting the communities downstream from the dam must take priority.