Unlike many municipalities, Missoula storm drains are not connected to a larger runoff disposal system. Instead, most street drain leads to its own dry well, an excavated hole in the ground filled with gravel and other aggregate materials. Because of its proximity to the surface, the Missoula Valley Aquifer is particularly susceptible to contamination from pollutants dumped into these drains. Motor oil, fuels, solvents, insecticides and other dangerous substances poured into the street or on the ground can seep down through these dry wells and into the drinking supply. To find out more about what you can do to keep pollutants out of our drains and protect the Aquifer, click here.