Land-use planning is a form of public policy that seeks to order and regulate land use to prevent conflicts. Land-use planning often leads to land-use regulations, also known as zoning, which prescribe the types of activities allowed on a given piece of land. Land use and development choices and policies can affect the hydrogeology of ground and surface water sources. Potential contaminants introduced directly or indirectly to the land surface through various land-use activities can infiltrate the soil and reach ground water or run off the land surfaces to receiving waters. Land-use planning and zoning can protect source water by assessing and controlling high-risk land uses and protecting sensitive areas.

Planning and zoning are handled locally, not by state or federal authorities. However, the Idaho Local Land Use Planning Act (Idaho Code 67-6537) requires local governing boards to consider impacts on ground water quality when amending, repealing, or adopting a comprehensive plan. Additionally, cities and counties can integrate source water protection into their local comprehensive plan, and source water areas into land-use planning and zoning regulations.

Possible tools to enhance source water protection through planning and zoning include subdivision and growth controls to reduce septic systems or zoning or land-use prohibitions to control dangerous substances and activities involving these substances. For example, prohibit gas stations in sensitive areas, require setback zones for septic systems, or restrict specific pesticide, fertilizer manure, and sludge applications.