Learn About Streams

What happens in and around streams impacts the streams themselves and the lakes they flow to

Learn about...

  • The Watershed
  • Tippecanoe's Mussels
  • What's in the Water?
  • Floods
  • Human Impacts

  • The Watershed

    Like our lakes, our streams are not isolated bodies of water. They are fed from a variety of sources. Some water comes to streams directly from rain, snow, or other ditches or streams. Other water comes to them indirectly, flowing downhill over the surface of the land or through groundwater before making it to the stream. This water that comes indirectly has a huge impact on water quality. The area of land that water flows over or through to get to a lake is called a watershed. Whether they know it or not, every single person lives in a watershed. The water that hits your backyard will eventually make its way to one of our streams. So what it goes through before it gets to the stream is important! Water doesn't just stop moving once it gets into a stream. It continues moving on until it gets to an ocean. For example, water might drain into the Tippecanoe River, but once it flows through there it ends up in the Wabash River, which flows to the Ohio River. The Ohio eventually drains into the much larger Mississippi River. Once in the Mississippi, water from your own backyard is on its way to the Gulf of Mexico!

    The way that land is used within a watershed determines, to a large extent, the water quality of the lake or stream it drains to. Sediments (soil that has been washed into the water), organic materials such as leaves and plants, nitrogen and phosphorus from fertilizers, toxic substances, bacteria, and other contaminants can enter lakes and streams through pollution that comes from a specific location (like a pipe from a business) or from many locations - including water that flows over the land from cities, landfills and agricultural areas. So the actions we take on our lawns, in our driveways and on our streets affect not just those areas but our lakes and streams as well. That is why it is so important that we are careful with how we treat the land around our homes and in our cities, not only along a lake or stream shoreline. If you are taking steps to protect water quality on your property, you are making a difference in the water quality of our lakes and streams no matter how far away from one you live!

    Tippecanoe's Mussels

    The Tippecanoe River officially begins at the outlet of Lake Tippecanoe and has a watershed that encompasses 1.25 million acres and spans 14 counties. Because of the number and diversity of the imperiled species that live in this river, The Nature Conservancy has rated it as the eighth most important river in America to preserve. Among those imperiled species are six fish and mussel species that are listed as federally endangered. One of those mussels, the club shell, has its largest and most significant population in the world in the Tippecanoe River. Unique fish include the ancient paddlefish and sturgeon, as well as the American eel and four darters (Tippecanoe, bluebreast, gilt, spotted) that are endangered in Indiana. The Tippecanoe is also home to a growing population of river otters, a species that was once one of Indiana's endangered species and still remains a "species of special concern." Their population is growing due to a reintroduction effort led by the DNR Fish and Wildlife Service in the late 1990's. Despite what The Nature Conservancy called "a relatively pristine past," the Tippecanoe River is being degraded by increased sediment which negatively affects its plant and animal life.

    What's in the Water?

    When studying streams, we look at many of the same parameters we would with a lake. These include dissolved oxygen, pH, nutrients (nitrogen and phosphorus) and bacteria.

    Dissolved oxygen is the major factor that determines where organisms can survive in an aquatic system. Most fish need at least 5 mg/L to be present in order to live, and if there is not enough oxygen you might see a fish die-off.

     The pH of water (how acidic or basic it is) is an important factor influencing aquatic life. Most aquatic organisms survive best in the pH range of 6.5-9.0. Values higher or lower than this range may interfere with important biological functions such as reproduction and respiration.

    Phosphorus is a plant nutrient that has few natural inputs to lakes since it does not come from the atmosphere. It enters waters primarily through fertilizers, human and animal waste, and yard waste. Because phosphorus is the least abundant nutrient, it is often referred to as the limiting nutrient for growth of aquatic plants and algae and has the potential to cause excessive plant growth. Soluble reactive phosphorus (SRP) is dissolved phosphorus in a form that plants can immediately use. SRP is usually low in water samples since plants tie up phosphorus as soon as they can. Total phosphorus includes all dissolved and particulate phosphorus in the water, and levels higher than 0.03 mg/L can cause algal blooms. Phosphorus is often targeted for reduction in water protection projects because, in excess, it can cause undesirable plant growth and speed up the lake aging process.

    Nitrogen is an essential plant nutrient and can be found in fertilizers, human and animal waste, yard waste and air. Nitrogen gas makes up 80 percent of the air we breathe and naturally diffuses into water, where it is converted by blue-green algae into usable form. Nitrogen also enters waters as a result of human influences in the forms of inorganic nitrogen and ammonia. Nitrogen can be present in lakes in three forms. Nitrates (NO3) are dissolved nitrogen which are converted to ammonia by algae and are normally found in surface waters. Ammonium (NH4) is dissolved nitrogen which is in the preferred form for algae use. It is formed by the decomposition of organic matter and is usually found in the oxygen-depleted bottom waters of lakes. Organic nitrogen includes all the nitrogen found in plant and animal materials and can be dissolved or in particulate form.

    Bacteria - Natural waters have a variety of microorganisms that live in them, including bacteria, viruses, protozoa, fungi and algae. Most of these are natural and have no effect on human health. There are, however, some microorganisms that do cause disease in humans and must be monitored. Viruses and protozoa cause many of the illnesses associated with swimming, but since they are often difficult to detect the bacteria E. coli is usually tested as an indicator for health risks associated with aquatic recreation. For water to be swimmable (or suitable for full body contact), the geometric mean of five water samples must not exceed 125 colony forming units (CFU) of E. coli per 100 mL of water and must never have one sample with more than 235 CFU of the bacteria per 100mL. Full body contact in water that exceeds these limits usually results in gastrointestinal illness that is easily treated, but in highly polluted waters disease may become more serious. E. coli bacteria is usually associated with the feces of warm-blooded animals and can come from humans, livestock and many other animals including wildlife such as geese and ducks.

    Stream researchers also often use aquatic insects as biological indicators of stream health. These little critters live in the streams themselves, often in the sediments or on the undersides of rocks. Certain species are very sensitive to pollution, and the presence of those species indicates a healthy stream. Conversely, certain species are very tolerant to high levels of pollution, and their presence can indicate degraded water quality.

    In addition to chemical and biological assessment, stream researchers will complete a habitat assessment. The land along the edges of a stream is called the riparian habitat, and what goes on there has a major impact on the stream. The condition of the land in and near the stream is important to its ability to support aquatic life. Habitat assessments generally evaluate land use, stream bottom (substrate), flow, depth, shape, vegetation and erosion.


    Floods are natural events that are an important part of the ecology of streams. In fact, some plants along the streams edge depend upon flooding cycles for their existence. Many fish wait until spring floods to breed, and many insect larvae take flooding as a cue to lay eggs, hatch or metamorphose. Floods also wash debris, insects and worms into streams that act as habitat and food for other stream creatures. For people living close to streams, however, floods can cause damage to homes and property. If you're building a house near a stream, always try to stay out of the floodplain to avoid flood damage.

    Human Impacts

    Streams are easily impacted by human activity. Among the activities that impact streams are dams, channelization, development, logging, urban runoff, drawing drinking water and the destruction of wetlands. These activities, if undertaken, must be done with care in order to protect the balance of the stream ecosystem.

    Notes: For more detailed information on stream ecology, visit the stream ecology primer at Water on the Web.