This paper summarizes Portland, Oregon’s program, primarily one of preventative containment, for protecting groundwater in the Columbia South Shore area (See Figure 1) from hazardous materials spills The approach was defined in a groundwater quality protection plan adopted by the City Council in April 1987. A handbook published in May 1988 provides design information for the required containment facilities. The compliance review process is outlined in a city ordinance adopted in May 1988 which addresses prohibited uses, the type of proposed developments which must include containment facilities, and uses which are prohibited unless approved on a development by development basis. The need for the plan and program was determined through a risk analysis, which found that a very high risk to the city well field existed.