Rivers and Streams
Utah's Rivers and streams carry water and sediment down from our mountain ranges, through our valleys and into our communities. Along the way they shape our landscape, carving narrow slot canyons and wide river valleys. Forming at a watersheds' high spots, streams flow downhill, joining nearby streams to form rivers.
DYNAMICS OF RIVERS
Stream flow, or discharge, is the amount of water that flows past a specific point in a stream over a specific period of time. Climate and season, as well as the streams location within a watershed, help determine flow of a stream. In Utah, our streams experience higher flows in the spring, as snow from our mountains melts.
Among other factors, groundwater has a big impact on stream flow, especially during drier seasons. Groundwater seeps out of springs in the stream bed, maintaining flows and keeping stream temperatures cool enough to support aquatic life. Excessive withdrawls of groundwater often cause nearby streams to run dry.
Low flows often correspond to higher stream temperatures and concentrate pollutants: maintaining adequate stream flows during summer is crucial to ensure the health of our streams.
Check out this video explaining the math behind calcualting stream flow.
Depending on thier location in a watershed, streams form three distinct shapes.
Meandering –A stream that meanders a lot makes many, tight “S-turns.” We often find meandering streams in valley bottoms with little slope. Check out this video on why streams meander.
Straight –Streams that run down steeper slopes may not meander much at all. Their fast waters erode downward until they are often confined by a deep, narrow channel of bedrock.
Braided – Braided stream channels continually split and re-join. Loose bed material and sparse vegetation allow these channels to move great distances across flat, broad valley floors.
BIOLOGICAL ASPECTS OF RIVERS
Besides fish, there is a fascinating array of “bugs” and plants that are support the ecosystems of water bodies. There are both those we can see and those we can’t.
Phytoplankton are tiny plants that use sunlight and nutrients in lakes to grow. Polluted lakes may host 'algae blooms' which can suck oxygen out of the water and may be toxic to humans and animals.
Zooplankton are small animals that drift in the water column and feed on phytoplankton and smaller zooplankton.The main groups of zooplankton are Rotifers, Cladocerans and Copepods. During poor conditions, they are able to make a resting egg which may sit for decades and still be viable when conditions improve.
Zooplankton are the favorite food of many types of fish and most juvenile fish.
Zooplankton and phytoplankton are found in the limnetic zone, the open water area of the pond or lake where light does not generally penetrate to the bottom.
These animals include many types of insects as well as other animals such as worms, mollusks, and crustaceans.
Macroinvertebrates usually live in the shallow-water area around the edge of the pond amongst aquatic plants (e.g. cattails, water lilies and elodea). They are an important part of the food chain and a food source for larger fish.
Macroinvertebrates are often used as indicator species to determine the health of water. Some species are more sensitive to pollution than others. In ponds and lakes dragonflies and mayflies are indicative of a healthy aquatic community.
Fish, besides being a source of food and recreation for people, are important members of rivers and are also indicators of water quality. Different species of fish have adapted to different water quality conditions. Some fish, such as the non-native carp, can tolerate warmer water temperatures, lower dissolved oxygen levels and higher turbidity. Some environments, like the Virgin River in Southern Utah, are naturally warmer and are suitable habitats for these “more tolerant” fish species.
Other fish species are sensitive to aspects of water quality including pH, turbidity, temperature and dissolved oxygen levels. The native Bonneville Cutthroat Trout, for example, feed on macroinvertebrates. Both the trout and their prey are sensitive to natural and human-induced changes in water quality.
WHAT POLLUTES RIVERS AND STREAMS?
Rivers and streams are vulnerable to many forms of pollution - both point source and non-point source. How we use our lands, from building homes to agriculture to forests, determines the types of pollutants we contribute to our rivers and streams.
Streams in agricultural areas are often prone to erosion (from livestock trampling riparian banks), diversion (lack of water) and runoff pollution. Learn more about reducing impacts of agriculture on water quality here.
WHAT ARE THE COMPONENTS OF A STREAM?
Streams and rivers are how surface water is transported through watersheds. Utahs' streams and rivers harbor unique plants and animals and face many challenges.
The vegetation along stream and river banks is known as the riparian zone. Click here to learn more riparian zones and their importance to water quality.
Utah Water Watch volunteers measure pH, temperature, E. coli and cyanobacteria at a their site, often a river or stream.. The program is perfect for educators, aspiring scientists, and anyone who likes spending time outdoors. Learn how you can help take care of your local streams here.