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Ammonia pollution could be biggest threat to Delta smelt

Posted by: Aqua Blog Maven on June 11, 2008 at 6:31 am

From Stockton’s Record:

Maybe it’s not the giant pumps at Tracy that send Delta water to the southlands that are killing the Delta smelt.

Maybe it’s toxic levels of ammonia released from upstream wastewater treatment plants, according to two recent studies. If that’s the case, look for more expense as those plants are upgraded.

Ammonia, a common byproduct of human urine and feces, is entering the labyrinth of waterways that make up the estuary from one primary source: Sacramento. That city’s regional sewage treatment plant is the largest single source of ammonia in the Delta. It discharges treated wastewater from nearly 1.4 million people into the Sacramento River near Freeport without removing ammonia. In fact, the ammonia load in Sacramento’s wastewater has more than doubled since 1985 due to rapid urbanization and is now more than 125,000 gallons per month. That’s 10 times more than the Stockton sewage plant.

Ammonia is the primary culprit in fish kills. A report released last fall based on data from the Environmental Protection Agency alleged Stockton violated its wastewater discharge permit 50 times in 2005, with ammonia levels exceeding its permit by anywhere from 23 percent to 1,245 percent.

Stockton officials disputed the figures when they were released but point out that a $42 million upgrade to the plant, including equipment that uses bacteria to eat ammonia before it is discharged into the river, has alleviated the problem. Not so in Sacramento.