Marin Independent Journal: Novato Creek work could help battle sea-level rise, report finds

Inline image 2
Dredge work takes place in September along Novato Creek. Sediment from the creek could help protect
against sea-level rise and reduce flooding, a new report said. Robert Tong — Marin Independent Journal
 
By Mark Prado, Marin Independent Journal
Inline image 3
The Novato Creek rose just below the bridge on Redwood Boulevard on Jan. 8, 2017. Robert Tong — Marin I.J.
 
Getting more sediment from Novato Creek into the bay to build tidal wetlands could be key in girding against sea-level rise while helping reduce flooding, according to a new report.
The same strategy could work with other creeks and channels around the bay, according to the report “Changing Channels” released by San Francisco Estuary Institute, a scientific think tank.
Tidal wetlands around the bay need sediment from outflowing creeks to grow and survive sea-level rise, according to the group. But some of the channels — like Novato Creek — have sediment flow restricted by flood control levees in their lower bayside reaches.
Tidal inflows from the bay that normally scour the creek are constrained by levees and sediment tends to stay on the creek bottom. The channels then need to be dredged to maintain flow, but that work can harm plants and wildlife.
The report — released last week — says there may be ways to open up the creek to allow for better tidal flow, which would help transport sediment onto wetlands while clearing more space in the creek for floodwaters.
“It’s putting Mother Nature to work, and becoming more in-sync with Mother Nature,” said Liz Lewis, planning manager with the Marin County Department of Public Works, which had input on the report. “We have to start looking at the long term.”
Lewis said it may be possible to build new levees to give the creek a wider berth to allow for some of the natural processes to take place. “If you open up the creek you get that scour power to the lower channel,” said Scott Dusterhoff, primary author of the report. “If we build up the baylands you can decrease the intensity of wave action. As we have bigger storms with higher waves there is then some protection for Highway 37 and other infrastructure. It’s a buffer.”
In the interim, flood managers could use dredged sediment to help build wetlands, which in turn could help diffuse the higher wave action brought on by rising water levels, Lewis noted. That would protect buildings on land from flooding.
Because flood control channels at the bay’s edge often need to be dredged they can be costly for local taxpayers, so using nature to do the work would save money, the report notes.
The lower section of Novato Creek was eyed by San Francisco Estuary Institute specifically because it has abundant undeveloped space around it, but a relatively low annual watershed sediment yield, according to the report.
“Creek re-connection may provide some improvement in flooding risks and would allow sediment delivery to the marsh that would be recreated within the historical baylands footprint,” the report reads about Novato Creek.
The report was developed as part of “Flood Control 2.0,” an U.S. Environmental Protection Agency-funded project focused on bringing tidal wetland restoration into flood management projects at the bay’s edge.
The report has a “toolbox” element containing information about the amount of sediment currently trapped in flood control channels, the regulatory considerations for flood control channel management, and the economic benefits associated with managing flood control channels to better support tidal wetlands.
“Good science lets us work with nature for more cost effective, environmental and resilient flood protection and climate change solutions,” said Warner Chabot, executive director of the San Francisco Estuary Institute. “This is not ‘pie in the sky’ stuff. This Novato vision offers a road map to help local leaders to evaluate and approve projects to address complex problems around Novato Creek.”

Speak Your Mind

*

Time limit is exhausted. Please reload CAPTCHA.