Fertilizer run-off is a serious agricultural issue across the country, with excess nitrates entering water systems and causing algal blooms. These blooms can produce harmful toxins, damaging to humans and animals alike. Scientists in central California are experimenting with bioreactors to help improve regional water quality. These trenches are full of water-cleaning bacteria, which breathe nitrate and release harmless nitrogen gas. This gif visually describes the water filtration system on the experimental site in Castroville, California. (1) Excess water from the agricultural fields, full of nitrogen from the fertilizer, is collected by an underground drainage system. (2) This water is diverted to a retention pond, where it is temporary held until it is pumped through the bioreactor. (3) The experimental bioreactor in Castroville, CA has 12 channels, with differing levels of temperature and PH to test which combinations are most effective. Each trench is full of woodchips, which help to sustain the bacteria along with the nitrate. (4) Water that has been cleaned by the bioreactor flows out into the wetlands.