Hyacinth, an invasive and seasonal plant, is once again invading Stockton waterways. This year’s bloom came into downtown Stockton from the Tuolumne River, breaking off during the last storm. … ”If you can’t have a bar pilot enter the ship from San Francisco Bay and come upstream because their radar is showing large mats of hyacinth, they pretty much call Stockton and West Sacramento saying we’re gonna have to drop anchor because we cannot distinguish between land and the weeds,” California State Parks Boating and Waterways Environmental Program Manager Edward Hard explained. Hyacinth also brings mosquitoes [and affects] water conveyance.