Flow in a headwater may be year-round, seasonal, or rain-dependent. The very foundation of our nation’s great rivers is a vast network of unknown, unnamed and underappreciated streams. Almost 60 percent of stream miles in the continental U.S only flow seasonally or after storms. About 53 percent of the total stream miles in the continental U.S. Headwater streams and streams that only flow for part of the year make up the majority of river miles in the United States. Yet other headwaters originate in marshy meadows filled with sluggish tea-colored water. Other spring-fed headwaters contain clear water with steady temperature and flow. Desert headwater streams can arise from a spring and run above ground only a few hundred yards before disappearing into the sand. Headwaters can be streams that flow briefly when snow melts or after rain, but shrink in dry times to become individual pools filled with water. Headwater streams are the smallest parts of river and stream networks, but make up the majority of river miles in the United States. Because small streams and streams that flow for only part of the year are the source of the nation’s fresh waters, changes that harm these headwaters affect streams, lakes and rivers downstream. Headwater streams trap floodwaters, recharge groundwater supplies, remove pollution, provide fish and wildlife habitat, and sustain the health of downstream rivers, lakes and bays.
Headwater streams are the beginnings of rivers, the uppermost streams in the river network furthest from the river's endpoint or confluence with another stream.
Like the photos on this page? Visit our Flickr Gallery to see more streams. These small streams often appear insignificant, but in fact are very important, as they feed into and create our big rivers.On this page: These water sources, which scientists refer to as headwater streams, are often unnamed and rarely appear on maps.Yet the health of small streams is critical to the health of the entire river network and downstream communities. They could be a drizzle of snowmelt that runs down a mountainside crease, a small spring-fed pond, or a depression in the ground that fills with water after every rain and overflows into the creek below. Small streams, including those that don’t flow all of the time, make up the majority of the country’s waters.