Federal Water Tap, August 24: Groundwater Flooding in California

The Rundown

U.S. Geological Survey researchers map groundwater flood risk in California. The Pebble Mine runs into trouble. The Army Corps begins the environmental review process for a San Francisco flood risk study and a Delta tunnel study. A federal lead advisory committee will hold a public meeting. And lastly, two tropical storms point toward the Gulf of Mexico.

By the Numbers

5 to 10 inches: Projected rainfall total along the Louisiana-Texas border from Tropical Storm Laura, which is expected to strengthen into a hurricane. Some locations could see as much as 15 inches between Wednesday and Friday. That storm will be preceded by Hurricane Marco, a weaker system that is expected to produce 3 to 5 inches of rain along the Alabama, Mississippi, and Louisiana coasts. (NOAA)

News Briefs

Pebble Mine Stirrings
The Trump administration will announce today that, pending further review, it will withhold a Clean Water Act permit for the controversial Pebble Mine, the Washington Post reports.

The open-pit, gold and copper mine has been criticized for its environmental impact — destroying rivers and wetlands and risking a release of toxic mining waste. It would be located in the Bristol Bay watershed of southwestern Alaska, upstream of one of the world’s most lucrative wild salmon fisheries.

The Post reports that the U.S. Army Corps of Engineers will ask the mine developer to show how it would offset the environmental damage.

Studies and Reports

San Francisco Bay Flood Study
The U.S. Army Corps of Engineers is beginning the scoping process for an environmental analysis of flood risks along 7.5 miles of San Francisco’s waterfront.

Highways, buildings, and other assets worth billions of dollars are vulnerable to rising seas, storm surges, and earthquakes.

During scoping the Corps will gather public input on the parameters of the study. Send comments by October 21 to SFWFRS@usace.army.mil.

Groundwater Flooding in California
Floods can come from above – storm surge, heavy rainfall, high tides. But they can also emerge from below, as rising seas lift coastal groundwater tables.

U.S. Geological Survey researchers assessed the extent of groundwater-related flooding in California as ocean levels rise. They found that with 1 meter of sea-level rise, the area susceptible to flooding from rising groundwater moves inland between 50 and 130 meters, depending on local geological and topographical factors.

In context: Hidden Flood Risk for San Francisco Bay Area Communities Lurks Underground

Delta Tunnel Study
The U.S. Army Corps of Engineers is also beginning the environmental review process for a water conveyance tunnel through the ecologically sensitive Sacramento-San Joaquin Delta.

A tunnel through (or around) the delta has been discussed for decades. The latest version, estimated by the state to cost $15.9 billion, is a product of Gov. Gavin Newsom’s administration.

Public comments on the scope of the study should be sent by October 20 to Zachary.M.Simmons@usace.army.mil.

On the Radar

Lead Advisory Committee Meeting
The expert group that advises federal health agencies on matters related to lead poisoning will hold a public teleconference on October 30, from 9:00 a.m. to 4:30 p.m. Eastern. Registration is required.

Federal Water Tap is a weekly digest spotting trends in U.S. government water policy. To get more water news, follow Circle of Blue on Twitter and sign up for our newsletter.

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