This column originally appeared in the September 2, 2007 issue of the Poughkeepsie Journal.

One of the best known and least helpful facts about the Hudson River is that its source is Lake Tear of the Clouds in the Adirondacks. Although it's true that Lake Tear of the Clouds is the source of the Hudson in the geographers' sense of the word (the highest-elevation stream that feeds into the river), it isn't the source of the Hudson in the way that most of us think of "source" (the place where its water comes from). The true source of the Hudson is the myriad of tiny streams that arise in the forests of the Adirondacks and the Catskills, in the farm fields of Orange County, in the malls along Route 9, and in your back yard.

These little streams, collectively known as headwaters, play a major role in shaping the character and value of the larger streams and rivers that they feed. Most of the water in the Hudson got there by passing through headwater streams. Between the time that a raindrop falls to the ground and the time that it reaches the open ocean, it spends a great deal of its time in headwater streams. As a result, these little streams not only provide the water that fills the Hudson other large streams and rivers, but they also change the quality of that water. Headwater streams can remove nutrients and other pollutants, retain sediments, slow down flood waters and thereby reduce flood severity, and keep streams cool during the summer.

In addition to protecting the ecological value of larger streams, headwaters are themselves important habitats. They support a rich community of plants and animals, many of which live only in headwater streams. In our area, plants like watercress and the peculiar red alga Batrachospermum, and animals such as brook trout, sculpins, and two-lined salamanders make their homes in headwater streams. Many other species of fish move into even the tiniest of headwaters from larger streams for part of the year to take advantage of rich feeding grounds, nursery areas, or cool water. Animals living in the surrounding landscape, such as insect-eating birds, bats, and other mammals, find food, shelter, and dispersal corridors along headwater streams.

Despite their ecological value, headwater streams often are neglected. They typically receive little legal protection, and many headwater streams don't even appear on maps. As a result, they are subject to "the death of a thousand cuts" as people straighten their channels, dump junk into them, pave their banks and surrounding areas, remove streamside vegetation, and use harmful chemicals in and near them. Damage to these tiny streams inevitably leads to problems in larger streams and rivers, as sediments choke their channels, nutrients and warm waters lead to outbreaks of undesirable plants and animals, and floods become more severe downstream.

We can protect these little streams and the larger rivers that they feed by taking a thousand small, simple actions in our own back yards. We can try not to disturb the beds or banks of streams, and keep construction activities and impervious surfaces – such as blacktop, concrete, or paving – away from the immediate vicinity of the stream channel. We can plant or protect vegetation along small streams, and keep potentially harmful chemicals such as pesticides and fertilizers out of the streams and surrounding areas. And we can begin to take even the smallest streams into account when we make local planning decisions.

Dr. David Strayer is an aquatic ecologist at the Institute of Ecosystem Studies in Millbrook, NY.