The scientists studied water quality in the Rio Grande Valley, focusing on the Rincon Valley in New Mexico. They collected samples from surface water and shallow groundwater to analyze various substances like nutrients, trace elements, and pesticides. They found that dissolved solids and nitrate levels were higher in the drains compared to the Rio Grande. Pesticides were detected in many surface water samples, with DCPA and metolachlor being the most common. In shallow groundwater, dissolved solids exceeded recommended levels in most samples, as did sulfate and nitrate levels in some wells. Trace elements were generally low, but uranium levels exceeded the proposed limit in a small percentage of samples.