Land & Water Connection

Forests as Water Managers

The forest ecosystem and the water cycle work as a single, interconnected system. The canopy slows, filters, and absorbs rainfall before it ever becomes runoff. When rain hits leaves and branches, its impact is softened, reducing erosion. On the ground, forest litter — the leaves, twigs, and organic matter — acts like a sponge, slowing water and letting it soak into the soil to recharge groundwater and sustain streamflow during dry periods. Beneath the surface, tree and understory roots trap sediment, absorb nutrients, and store water, while also breaking down certain pollutants before they can reach streams, lakes, or the aquifer.

What Happens When Trees are Lost

With Canopy: Rainfall is slowed, filtered, and stored in the soil. Runoff is cleaner and aquifer recharge is higher.
Without Canopy: Rain hits the ground hard, eroding soil and carrying pollutants into waterways. Less water infiltrates, leading to faster, more forceful runoff and reduced groundwater recharge.

Our Watershed Connection

We’re located at the headwaters of the Conewago Creek watershed, a 53.2-square-mile drainage area that begins just northeast of Mount Gretna and flows southwest into the Susquehanna River, ultimately reaching the Chesapeake Bay.

What happens here affects water quality downstream — impacting not just our community, but aquatic life and ecosystems all the way to the Bay. Protecting forest health in Mount Gretna means protecting clean water for thousands of people and hundreds of species far beyond our borders.

The Economic Value of Forest Protection

Healthy forests aren’t just an environmental asset — they’re a financial one.

• • Cost savings: Communities with more forest cover in their watersheds spend less on water treatment, because forests filter pollutants naturally.

  • Stormwater management: An acre of urban forest can reduce the annual load of nitrogen in stormwater by 21–82 pounds, phosphorus by 0.31–1.3 pounds, and total suspended solids by 520–1,500 pounds — all pollutants that would otherwise need costly removal downstream.

  • Infrastructure protection: Forests slow runoff, reducing strain on stormwater systems and lowering the risk of costly flood damage.

Protecting the forest is an investment in the community’s long-term water security and resilience.

Why This Matters for Mount Gretna

Here, healthy forests are part of our water infrastructure every bit as much as pipes, tanks, and treatment plants. But unlike built systems, forests work around the clock — quietly, for free — as long as they are cared for and managed wisely. Stewardship matters: protecting tree canopy, maintaining soil health, and managing invasive species all ensure these natural systems can keep intercepting rainfall, filtering pollutants, and recharging groundwater for generations to come.