Water hyacinth has been on the Delta for decades, but really exploded in 2011 and 2012 as officials were not able to obtain a permit to spray chemicals in a timely fashion. Efforts to control hyacinth in the Deltas focuses primarily on the use of chemical herbicide applications.
Officials aggressively spray chemicals; a prepared document says the state has spent $5 million to $6 million a year applying thousands of pounds of chemicals in the Delta. Despite the aggressive treatments, for the second year in a row there is a bumper crop.
The Port of Stockton spent nearly $25,000 on a private contractor last year to harvest the hyacinth in the Stockton Deep Water Channel. The concern is that the enormous mats of vegetation would prevent oceangoing ships from traveling at night; therefore the Port is hiring the same contractor again this year.