If most Missouri streams were in peril, would you notice? Fertile stream floodplains were the first home to our settlers and rivers were our first highways of interstate commerce. Streams water our crops, provide our livestock and wildlife with ample vegetation, transport grain and fertilizer, and give us clean water for drinking and bathing. We seek out streams during hot summers to fish, float, swim and chase crawdads. Much of who we are and what we do depends upon clean and healthy streams. But many Missouri streams have been clogged with silt, poisoned by pollutants and overrun by development. Part of the problem is that many of us might not know a stream when we see one.
There are three main types of streams: perennial, intermittent and ephemeral. The differences between these can be vague because they reside on a continuum of connectedness, like veins in a body. These water bodies are all intricately related and affected by each other.
Perennial streams maintain flow throughout the year except during times of extreme drought. Perennial streams are what most people envision when they think of streams. But these make up only about one-third of all Missouri streams. At the other end of the stream spectrum from perennial are ephemeral streams. Ephemeral streams are wetted only in direct relation to the amount of rainfall received in the watershed—no rain, no flow. Intermittent streams fall somewhere between ephemeral and perennial in size, but certainly not in terms of importance. Intermittent streams have wet and dry seasons, flowing with water during the rainy spring and fall and drying to an underground trickle with occasional shrinking surface pools during summer. When flowing, they average only about 10 feet wide and 7 inches deep. But what intermittent streams lack in volume they make up for in value. In Missouri, intermittent streams far outnumber and are critical to the health of perennial streams.
Intermittent streams are full of life. Even when they appear dry their water is flowing beneath the surface, invisible to any casual observer. These streams are teeming with hundreds of species of insects, snails, mussels and other invertebrates—a vital food source for larger amphibians, reptiles, fish, birds and mammals. Intermittent streams support large and diverse food webs throughout the year. They provide critical spawning and nursery sites for many species of commercially, recreationally and ecologically important fish. Their surrounding trees and vegetation often provide