Forests protect and purify water. Forest soils act like a huge sponge, capturing and filtering amazing quantities of rainfall. They slow runoff, preventing soil erosion and the resulting stream and lake sedimentation. They also filter pesticide and nutrient runoff from agricultural fields and developed areas. This 8-page publication, part 5 of A Landowners Guide to Sustainable Forestry in Indiana, describes how we can improve water quality through good stewardship of our forests and neighboring land.