The researchers studied a pond that treats runoff from vegetable farms to understand what pollutants are in the water and how they change over time. They found that the highest levels of harmful metals came during big storms in 1998, but these levels were reduced by the pond. In a dry year, 1999, there were fewer pollutants because the fields were not being used. In 2000, more water was added to the fields, increasing pollutant levels. Some metals did not meet water quality standards at the beginning, but most were reduced by the pond. However, organic nitrogen levels did not decrease much because the pond actually added more nutrients. Overall, phosphorus levels were high in the water coming in.