A company operating a sand mining facility in Alameda County must pay hundreds of thousands of dollars to settle allegations it discharged untreated wastewater into Alameda Creek last year, officials with the State Water Resources Control Board said Thursday.

Mission Valley Rock Company must pay nearly the statutory limit after it allegedly discharged 41,000 gallons of untreated wastewater from its Sunol facility in March 2021.

According to the Water Board, Mission Valley Rock Company failed to properly decommission a pipeline, which ruptured, depositing several inches of sediment in the creek bed and along the bank. The discharge violated Mission Valley Rock's discharge permit, according to the Water Board.

"This fine serves as a reminder to everyone to pay attention to old infrastructure and protect our creeks," Thomas Mumley, interim executive officer for the Regional Water Board, said in a statement.

"It is close to the statutory maximum we can impose because this problem could have been avoided had Mission Valley Rock Co. properly decommissioned the pipeline prior to the discharge," Mumley said.

The discharge clouded creek water, threatening life in the creek and may have contained toxins such as grease, oils and metals, according to the Water Board.

Mission Valley Rock took out the ruptured pipe, cleaned the creek bank of sediment and trained its employees to prevent similar problems in the future.

But the company was unable to remove sediment from the active creek channel, Water Board officials said.

Mission Valley Rock Company must pay about $185,000 to the State Water Pollution Cleanup and Abatement Account and the same amount for a project to map and survey water quality. The company must also develop ways to monitor the growth of microscopic marine algae in San Francisco Bay.

The total settlement is $368,940.

Attempts to reach someone who could comment for Mission Valley Rock Company were unsuccessful.