The commonwealth's northern tier is enjoying the season's burst of color as fall foliage reaches its peak there by mid-October. The palette will sweep southward, sharing its vibrancy with the rest of Pennsylvania as temperatures continue to cool and days grow shorter toward the end of the month.

The Pennsylvania Department of Conservation and Natural Resources boasts that the Keystone State, with its 134 species of trees, has a longer and more varied fall foliage season than anywhere else in the world.Folks travel for miles to marvel at the splendor of the changing leaves. There are ways to further appreciate what fall foliage offers, after it falls in our own neighborhoods.Putting leaves to work is good for plants and properties, and contributes to the health of Pennsylvania waterways.The commonwealth is significantly behind in its clean water commitments and must accelerate its reduction of nitrogen, phosphorus and sediment runoff into rivers and streams and ultimately the Chesapeake Bay.Urban/suburban runoff of pollutants is the third-leading cause of impairment to 19,000 miles of Pennsylvania waters; behind agricultural runoff and acid mine drainage respectively.Trees play a key role in defending clean water by filtering pollution and absorbing runoff.Making the most of fall leaves around the home and other properties can reduce the amount of fertilizers needed and enhance soil absorption, reducing the amount of runoff that carries harmful pollutants into waterways.Autumn leaves are some of the best organic matter, are packed with trace minerals that trees draw from the soil, and can be a powerful benefit around the home.Healthy compost is a valuable and plentiful alternative fertilizer and soil enhancement for flower beds and gardens. Leaves are an effective component of compost, which also reuses grass clippings, food and yard waste, and other natural ingredients. Carbon-rich leaves add balance to nitrogen-rich elements like fresh grass clippings.Shredded leaves are multipurpose. Shredding leaves reduces the volume, creates more surfaces for microbes to work, and more easily loosens the soil when worked into the garden. This invites earthworms and other orgasms that are beneficial to productive soil. Shredding and mulching is as easy as piling leaves up and driving over them a few times with the lawn mower.Against winter wind and cold, a 6-inch blanket of leaves can protect tender plants. Some gardeners use leaves to insulate sensitive dahlia, iris and other bulbs left in the winter garden.Making "leaf mold" by simply raking leaves into a pile is a low-maintenance process for augmenting soil quality. Shredding leaves allows them to decompose faster, but is not a requirement for good leaf mold. Over the period of a few years, fungus breaks the leaves down into a special compost that is high in calcium and magnesium. It also retains three to five times its weight in water.To enhance your fall foliage experience, the DCNR website (www.dcnr.state.pa.us/forestry) offers a weekly fall foliage map and reports, an explanation of why autumn leaves change color, and state forest maps with directions. After they've fallen, make the most of them.Clean water counts in all seasons, and for many Pennsylvanians, fall is their favorite time of year. Putting leaves to work to reduce polluted runoff can extend our appreciation of fall foliage long after the color is gone.Harry Campbell is Pennsylvania executive director of the Chesapeake Bay Foundation.