There are many reasons to protect groundwater. More than half of the United States relies on it for drinking water. The population of the U.S. has increased by 20 million in the past 10 years, while the amount of groundwater available for consumption has remained the same. One gallon of gasoline can contaminate 1 million gallons of groundwater. And the cost of contamination clean up far exceeds that of a prevention program. This report provides the information needed to start a wellhead protection program. It reviews the fundamentals of water hydrology, the causes and effects of contamination, wellhead management and protection, and financial strategies available to communities interested in starting a program. The report also includes a table of land uses and their potential contaminants, a matrix that describes regulatory and nonregulatory devices to be used in a program, and a sample ordinance.