A Citizen's Guide to Understanding and Monitoring Lakes and Streams

Chapter 3 - Streams

Developing a Stream Monitoring Program

Consider this – streams are moving targets. When you collect a sample of stream water, it reflects a mixture of unknown upstream conditions and characteristics. Say you sampled a shady, fast-moving portion of stream, where you’d expect cooler temperatures. If the segment just upstream (beyond your vision) had been a long stretch of shallow, sunlit, sluggish water, the temperature of you sample might be relatively high – not what you had expected. The water sample reflects upstream characteristics and not just those of the sampling site.

This problem becomes more complex when you consider the addition of nutrients or organic matter. When nutrients are added to a stream, they may not result in a measurable increase in algae growth until a few miles downstream, where temperature, sunlight, or other growing conditions are just right. The resultant mass of algae will eventually require oxygen for decomposition. However, even as the algae die, they are carried farther downstream so that the decrease in oxygen does not occur at the same point as the increase in organic matter. This is an important concept to understand when you are developing your monitoring plan. Data you collect may not reflect conditions at the site in the way you might expect.

Getting Started

Before beginning a stream water quality sampling program, it is helpful to do some map work. Begin with an U.S. Geological Survey (USGS) topographic map. These maps can be found in any map store and many local sporting goods stores. Depending on the length of the stream, you might need more than one map.

First, trace the boundary of the watershed. Start at the mouth of the stream, and moving laterally away from the stream, follow the rising topography lines until you reach a spot where the land elevation begins to decrease. This is the edge of the watershed – mark the point on the map. Make a number of these points on both sides of the stream and near the headwaters. Then try connecting the dots by following between the topography lines. This is the boundary of the watershed. If you have trouble drawing in the line, imagine dropping a ball in the area and think again about which direction it would roll. If it would roll toward the stream, then the area should be included in the stream’s watershed.

Use your knowledge of the area to add detail to the map, which is likely to be at least several years old. Many changes can occur in a watershed over several years, especially if it is in a developing area. Start by roughly outlining areas of the major land uses in the watershed. Show agricultural, rural, residential, urban, industrial, and any other category you find appropriate for your stream. If you know of a new mall or housing development, mark its location, too.

Next, think about the stream corridor itself. Do you know of places where the bank is very steep, eroding, or trodden down by farm animals? Do you know where stormwater pipes or culverts enter the stream? Have people discarded washing machines, tires, cars, and other junk along the bank? Mark these features on the map. Look at where roads cross over the stream and try to remember what the area near the road looks like. This might help refresh you memory about other features to note on the map.

Keep this stream map current. Place it in your glove compartment and make additional notes whenever you see something worth noting, big or small. You may be able to better understand the reasons for water quality changes by continually updating your map.

A more advanced form of surveying stream features is to take a "stream walk" or "stream survey." This entails selecting a stream segment and walking its length to make detailed notes on your observations. (Be sure to get landowner’s permission before starting out!) These notes should include the type and amount of streamside vegetation, the presence of logs or the large debris in the stream, the composition of the stream bottom, the presence of oil/film or algae scums, and other easy-to-recognize details. Standard checklists and field note forms are available to help you make good records. The U.S. Environmental Protection Agency (EPA) has a standardized streamwalk form and has developed a computerized database for inclusion of citizens’ streamwalk results. The reference section provides information on EPA’s program.

The next section discusses selecting sampling locations in streams.

Return to Table of Contents | Lakes | Streams | From the Field to the Lab | Hydrology

Last updated on April 01, 2008