How to Study a Waterway
 

There are three main ways of studying a waterway to determine its health and quality.

They include:

Chemical Testing

The condition of a waterway can be determined through a series of chemical tests. Chemical tests can sometimes pinpoint exactly what substance is polluting the waterway or the pollution source. Chemical testing has a longer history for being used to determine stream health, although biological monitoring is becoming more common. A biological test can indicate that a waterway is polluted, but chemical tests can help identify the exact pollutants. Because chemical testing is the most accurate and reliable method in water testing, chemical testing is the method performed on drinking water. Chemical testing may also assist in locating sources of pollution. For example, if the tests indicate that a high concentration of phosphates and nitrates are present in the water downstream of a farm but not upstream, one could hypothesize that fertilizer runoff is occurring around the farm. A list of chemical tests that are performed to determine water quality are listed below:

  • Alkalinity-Resistance to change in pH or acidity
  • Ammonia - Form of nitrogen, a nutrient for plants
  • Calcium - Natural from rocks, incorporated into a "hardness" test
  • Chloride - From salts, sea water, or industry
  • Chlorine-Common disinfectant to kill pathogens
  • Chromium- Toxic, corrosion inhibitor added to industrial cooling processes
  • Conductivity-Dissolved organic matter within water
  • Copper-May exist naturally as a soluble salt or suspended solid
  • Cyanide - Toxic waste product of metal plating operations
  • Dissolved O2-Presence of O2 molecule in water
  • Fluoride - Added to municipal water to strengthen teeth
  • Hardness - Calcium, Magnesium and determines if water is soft or hard
  • Iron-Natural, but in excess can indicate acid mine drainage
  • Magnesium - Natural from rocks, incorporated into a "hardness" test
  • Manganese- Needed by plants and animals, causes a bitter taste, also stains laundry
  • Nitrogen-Required by plants & animals to produce protein
  • pH-Measurement of hydrogen ion concentration, determines if water is acidic or basic
  • Phosphorus-Limiting growth agent in most organisms, causes too much growth if in excess
  • Salinity - Concentration of all ionic constituents of halides and bicarbonates (salts)
  • Silica - Natural nutrient for diatoms, used in their skeletal structures
  • Sulfates- Mineral common in water, nutrient, can be from acid mine drainage if in excess
  • Sulfide - From anaerobic (no O2) bacterial breakdown of organic waste, rotten egg smell
  • Temperature-Different aquatic organisms thrive in different temperature ranges
  • Total Dissolved Solids- minerals, organic matter, and nutrients dissolved, (not merely suspended) in the water
  • Turbidity-Cloudiness of water from visible sediments and particles
  • Zinc-Industrial effluents contribute large amounts of zinc

Biological Testing

The plants and animals that inhibit waterways are good indicators of the water's quality. A person can study the insects, fish, mussels, algae, other plant life, bacteria, and streamside creatures to make conclusions about a stream's health. The more variety of aquatic life present in a waterway, the better. The variety of life in any habitat is called biodiversity. In a healthy stream, many different types of insects or fish will be found throughout the stream. If only a few species dominates the waterway, then something about the stream is unhealthy.

Insects, molluscs, and worms living in streams and rivers are examples of macroinvertebrates (big enough to be seen by naked eye), or benthic (bottom dwelling) organisms. Microinvertebrates are insects that need a microscope to be seen. Benthic macroinvertebrates can be very accurate in detecting overall changes in water quality (not necessarily specific chemical parameters) because they: 1) reflect long-term condition of the stream from a variety of sources, 2) are ubiquitous, have high species diversity, and are more sensitive to changes in the ecosystem than fish communities, 3) live in bottom of waterway, where pollution associated water quality problems can be magnified. Fish and mussels can also categorize the health of a stream. It is debatable about which can reflect long term pollution trends better - fish or insects.

Every waterway in the world has the potential to host a variety of insects in its waters. However, many streams lose this capability when altered by pollutants naturally or through human interference. By polluting waterways, we disturb where the insects live in the stream, what they eat, and the chemical levels of the water that they can tolerate.

Different organisms have select tolerances to pollutants found within the water. Organisms that are sensitive to pollution will not inhabit those waters that are polluted. Some of the pollution sensitive macroinvertebrates (sometimes referred to as "group 1" organisms) examples include mayfly nymph, stonefly nymph, caddisfly larva, and the water penny beetle larva. Large numbers of pollution sensitive organisms generally indicate good water quality. Their response to extreme pollution can be to move by drifting (letting themselves get washed downstream to a different location) or to die.

A second group of aquatic organisms are more tolerable to a wide range of water quality conditions. Some of these organisms include water striders, crayfish, and whirlygig beetles. The pollution tolerable (group 3) organisms include blackfly larvae, leeches, and aquatic worms. These creatures are not sensitive to pollution, and may exist in very polluted waters.

A healthy stream will have organisms from each group. Just because pollution tolerant creatures are present does not mean the water is polluted. Check to see if there are any bugs from the other more pollution sensitive groups. If a stream does only contain group 3 organisms, it can be hypothesized that the stream is currently significantly polluted. Based on insects that you collect, the health of the stream can be calculated using a Pollution Tolerance Index (PTI). This handbook includes one for insects.

Pollution sensitive indexes are not restricted to analyzing insect populations in a waterway. Other species, such as fish, mussels, algae, and bacteria populations have also been analyzed using the same strategy behind the insect pollution indexes. In addition, the health of a waterway can also be estimated by observing bird and mammal interaction with the waterway. If you never see a common riverbank predator eat from a creek, (such as a raccoon), or you never see deer drink from the waterway, then there might be something wrong with the water.

Land Use / Habitat Assessment

This approach analyzes the physical habitat in and surrounding the waterway to identify possible pollution sources running into the river. Land use assessment is a quick, practical method of locating the source of pollutants found within the waterway. The first step to assessing land usage surrounding the waterway is to observe how the land surrounding the waterway is being used. Different types of land use generate different types of pollutants. Land use assessment is especially useful when human infrastructures and land alterations surround the waterway. Classify the land surrounding the water source as residential, commercial, agricultural, natural, or industrial. There are two types of sources of pollutant sources that enter waterways, point and nonpoint sources. Point source pollution is simply pollution that's source can easily be identified and pinpointed. Typical point sources of pollution are storm water drains, industrial waste discharge, sewage plants, and construction runoff. Even though point sources are regulated by law, they are a major threat to waterways. Nonpoint sources of pollution are scattered, diffuse sources of pollution that enter and are harder to identify the exact location of entry. Nonpoint sources can be identified or hypothesized by observing the land use surrounding the water source. Examples include: a pollutant leaching through the soil, nutrient enrichment from agricultural areas, storm runoff over an urban setting, fertilizers and pesticides from lawns.

A land use / habitat assessment is the RCE, or Riparian, Channel, and Environmental inventory. The RCE assessment is a 16 characteristic analysis of the physical and biological conditions for a 100 meter stretch in and along a stream. This assessment is used primarily used in streams that have been heavily modified by man. Land use, physical structures in the stream, and biota are explored by the RCE. The riparian zone, the vegetation alongside streams, is studied. They are important because they help control floods, prevent soil erosion, take up extra nutrients, and provide shade to the stream. Channel alteration, stream bank stability, and substrate condition are also studied by the RCE. To prevent flooding or to irrigate arid lands, humans usually modify channels. However, the ecosystem of the steam is dramatically altered, for pools and riffle zones become eliminated when the channels are manipulated. Smoothing a channel also removes plants, logs, and boulders (snag habitat). Alteration of a stream's channel drastically reduces the biodiversity of the stream, because it removes habitat diversity. The biota of the stream is also analyzed by the RCE. A calculated score can be determined at the end of the RCE that correlates with an overall stream condition (excellent - poor).

How You Will Study Your Waterways in this Project:

There are tests and analysis methods to study the chemical, biological, and land use/habitat characteristics of waterways included in this handbook. Chemical testing is required by the project throughout the school year, and biological and land use/habitat assessment is encouraged. Together, they can help determine the health of your stream and help you to better understand its threats and protection needs.  Have fun.