Water Chemistry

Water samples should be collected from the most represented portion of the reach, which is usually the run, and as close to the downstream end (X-site) as possible. If the most downstream end of the reach is a riffle or pool, walk upstream until you encounter a run. Collect the water sample in the deepest section of the run. This may not be the center of the channel depending upon physical features or the curvature of the channel. For example a curved (meander) channel is usually deepest on the outside bend. When wading to your sample location, be careful not to disturb the bottom sediments (or at least keep the disturbance to a minimum). Once you have located the deepest section (thalweg) and have a clean sample container ready, follow the procedure below. In most small wadeable streams the current adequately mixes the water, so it is not absolutely necessary to find the thalweg; however you should not collect samples in backwater or eddy areas.

1. Stand facing upstream. Collect the water sample on your upstream side, in front of you. You may also tape your bottle to an extension pole to sample from deeper water if the area cannot be reached.
2. Hold the bottle near its base and plunge it (opening downward) below the water surface. If you are using an extension pole, remove the cap, turn the bottle upside down, and plunge it into the water, facing upstream. Collect a water sample 8 to 12 inches beneath the surface or mid-way between the surface and the bottom if the stream reach is shallow.
3. Turn the bottle underwater into the current and away from you. In slow moving stream reaches, push the bottle underneath the surface and away from you in an upstream direction.
4. Leave about ½ inch air space (Except for DO and BOD samples). Do not fill the bottle completely, so that the sample can be shaken just before analysis. Recap the bottle carefully, remembering not to touch the inside.
5. Fill in the bottle number and/or site number on the data sheet. This is important because it tells the laboratory which bottle goes with which site.

Types of Analysis

Acidity, Alkalinity and pH; Bacteria E-coli/Fecal coliform; BOD Biochemical Oxygen Demand; DO Dissolved Oxygen; Conductivity; Nutrients (Nitrates and Phosphates); Metals from AMD; Temperature; Turbidity; and Total Solids (TDS and TSS). Because of the expense and difficulty involved, volunteers generally do not monitor for toxic substances such as heavy metals and organic chemicals (i.e. pesticides, herbicides (agriculture/urban), solvents, and PCBs (industrial/urban).

Additional Information

• Chemistry

  Water quality chemistry for water samples taken.

• Volunteer Manual

  USEPA's Volunteer Monitoring: A Methods Manual was written to provide a better understanding of the concepts and procedures needed to evaluate the conditions of streams and rivers.

• Filtering

  Filtering involves forcing water through a membrane filled with tiny holes, about 25 microns across (¼ of a human hair). The filter removes suspended solids from the water, and in fact, the weight of the solids caught in the filter is one common analysis parameter: total suspended solids (TSS).