Learn About Streams

The Watershed

Streams are not isolated bodies of water. They are fed from a variety of sources. Some water comes directly from rain, snow, ditches and streams, but other water comes indirectly, flowing downhill over land or through groundwater. This area is called a watershed, and it has a huge impact on overall water quality.

Watersheds are the area of land that water flows over or through to get to a lake. Everyone lives in a watershed! The water that hits your backyard will make its way to one of the streams, and eventually a lake. What the rainwater filters through is important because water doesn’t stop moving once it gets into a lake. It usually leaves that lake and continues moving until it gets to an ocean.

Watersheds help determine the water quality of the lake or stream it drains into. Soil that has been washed into the water likely contains:

  • Organic materials such as leaves and plants
  • Nitrogen and phosphorus from fertilizers, toxins, bacteria and other contaminants

Pollutants enter the water 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.

The actions we take on our property affect more than our lawn and driveway; they also affect our lakes and streams as well. It’s important to treat the land around our homes and in our cities with care, not only the land along a body of water. 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 begins at the outlet of Lake Tippecanoe. It has a watershed that covers 1.25 million acres and 14 counties. Due to the number and range of the endangered species living in this river, the Nature Conservancy has rated the river as the eighth most important to protect. Those species include six types of fish and mussels. In fact, the club shell mussel has its largest population in the Tippecanoe River. Endangered fish include:

  • The ancient paddlefish and sturgeon
  • The American eel and four darters, Tippecanoe, bluebreast, gilt, and spotted.

The Tippecanoe is also home to a growing number of river otters. This species was once endangered and still remains a “species of special concern.” Their population is growing due to efforts from the DNR Fish and Wildlife Service. Despite what the Nature Conservancy called “a relatively pristine past,” the Tippecanoe River is weakened by sediment. It negatively affects 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 helps determines where organisms can survive. Most fish need at least 5 mg/L to be present in order to live.

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. Higher or lower values interfere with biological functions like 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 a 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.


Flooding is an important part of stream ecology. In fact, some plants along the waterline depend upon flooding cycles. Many fish wait until spring floods to breed. 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 habitats 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, try to stay out of the floodplain to avoid flood damage.

Human Impacts

Streams are easily impacted by human activity: Dams, channelization, development, logging, urban runoff, drawing drinking water and the destruction of wetlands. These activities 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.