An inch of rain doesn't sound like much.
But spread that inch across 21 acres — roughly the area protected at Laurel Ridge Nature Reserve — and something remarkable happens.
One inch of rainfall on 21 acres produces more than 570,000 gallons of water.
Where all that water goes matters.
When rain falls on rooftops, pavement, parking lots and other impervious surfaces, it cannot readily soak into the ground. Instead, much of it becomes stormwater runoff, flowing across pavement and into drainage systems, culverts and streams. Along the way, that runoff can pick up sediment, road salt, oils, fertilizers and other pollutants before eventually reaching ponds, rivers and larger waterways.
A forest handles rain very differently.
The tree canopy intercepts some rainfall before it ever reaches the forest floor. Leaves, branches and trunks slow the water's journey downward. The layer of leaves and organic material covering the ground absorbs and holds additional moisture, while roots and naturally porous forest soils create pathways through which water can infiltrate.
Some of that water is taken up by trees and other vegetation and eventually returned to the atmosphere through transpiration. Some remains in the soil, sustaining plants and the organisms living there. Some moves gradually through the soil toward wetlands, streams and nearby surface waters. And some percolates more deeply, helping recharge groundwater.
The result is a remarkably effective natural water-management system.
Instead of sending a large pulse of water rapidly downhill during a storm, an intact forest catches it, slows it, stores it, filters it and releases it gradually.
That matters almost anywhere. Along the shoreline of Whitehall Reservoir, it matters even more.
Forested land surrounding the reservoir helps reduce erosion and runoff while allowing rainfall to move more naturally through soils and groundwater. That helps protect water quality and contributes to the larger hydrologic system connecting Laurel Ridge, Whitehall Reservoir, nearby wetlands and the surrounding watershed.
And the scale adds up quickly.
One inch of rain over Laurel Ridge represents more than half a million gallons of water. Four inches represents more than two million gallons. Over the course of a year, the average 45 inches of rainfall equates to 25 million gallons of precipitation that falls just on these 21 acres.
Not every gallon becomes groundwater, and not every gallon remains within the reserve. Nature's water cycle is far more complex than that. But keeping land forested allows far more of that rainfall to follow natural pathways rather than immediately becoming stormwater runoff.
Trees are therefore doing more than providing shade, absorbing carbon and creating wildlife habitat. Together with the soils beneath them, they are part of the watershed's natural infrastructure.
Cities and towns spend enormous sums constructing systems to collect, channel, treat and manage water after development has altered the landscape.
A forest has been managing rainfall all along.