Forests act like a sponge. The trees and soil within them absorb rainfall and melted snow, reducing the risk of extreme flooding. Also, the water absorbed eventually flows into rivers and streams that provide us with a steady supply of water. Forests also act like a filter. They keep water clean by preventing the runoff of chemicals and soil into waterways.
What does this mean for people?
- A steady supply of water. Fifty-five percent of America’s drinking water originates from forests — mainly the rivers and streams that run through them.
- Fewer extreme floods. Forests, especially those that run beside streams, retain and temporarily store rainwater.
- More recreation opportunities, such as fishing and kayaking in the waterways forests help keep clean.
- Lower costs associated with water treatment. Every 10 percent increase in forest cover in a watershed leads to a 20 percent decrease in costs for water treatment downstream from the watershed. Filtration provided by just one national forest (Wayne National Forest in Ohio) is valued at more than $3 million annually.
The loss of forests through deforestation — which, in the U.S., is primarily due to sprawling development — threatens the ability of forests to act as sponges and filters. So does forest degradation, which, in the U.S., is largely the result of insects and diseases that damage trees. Scientists predict that, by 2071, nearly half of the freshwater basins in the U.S. may not be able to meet the monthly demand for water—partly due to a decline in forest health. Jeopardizing the quantity and quality of our water supply is particularly concerning, given that our population is increasing.