LOS ANGELES (AP) — Environmentalists want California Gov. Jerry Brown to halt plans for hydraulic fracturing in the waters off Southern California.

State regulators this month approved nine permits for so-called fracking operations between August and December in Long Beach Harbor. The Center for Biological Diversity called on Brown Tuesday to halt the plans.

READ MORE: Jo Lasorda, Wife Of Dodgers Great Tommy Lasodra, Passes Away At 91

Center attorney Kristen Monsell says fracking would increase the risk of chemical pollution or an oil spill.

READ MORE: Marine Corporal Hunter Lopez Honored By Disneyland With Presentation Of Park's Flag To His Mother

Hydraulic fracturing is used to extract oil or gas from rock by injecting high-pressure mixtures of water, sand or gravel and chemicals. The group says the permits allow the first offshore fracking in the state since 2013.

Brown’s administration did not immediately respond to a request for comment.

MORE NEWS: Thousands Of Hollywood Workers Nearing Historic Strike Vote

(© Copyright 2015 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)