Oregon regulates UICs to protect groundwater resources. In Oregon, 70 percent of communities depend on groundwater as their source of drinking and irrigation water. Fluid injected into the ground that is contaminated from sources such as industrial businesses, auto repair shops, chemical spills and animal waste may reach groundwater through improperly or illegally used UICs, causing groundwater contamination. Once groundwater contaminated, it is costly, difficult, and sometimes impossible to clean up.