Standard Practices for Sampling Water

The United States Geological Survey division of the United States Department of the Interior drafts manuals that outline standards that should be utilized during the collection and testing of water quality data. The revision in September 2006 includes a special chapter on the collection of water samples to include responsibilities, field preparations, prevention of contamination, surface-water sampling, groundwater sampling and quality control. Conversion factors, abbreviations and selected terms and resources are also listed in the manual.

Preparation

• People conducting water sampling must ensure they are prepared. This includes getting the proper equipment, reviewing and following data-quality requirements and being aware of contamination sources. People should get training and certification as needed for work in hazardous sites. Testers should get the most recent versions of the Quality-of-Water Data, Automatic Data Processing System and Ground-Water Site Inventory guidelines so they may be completely filled out during the testing process for use by the National Water Information System. Testers should also use non-contaminated materials and carefully handle equipment and samples with clean hands to prevent contamination.

Surface Water

• Collecting surface-water, flowing-water and still-water samples depends on the flow of the water, safety, equipment specifications, general conditions, objectives and data requirements. You can collect using equal-width-increment, equal-discharge-increment, non-isokinetic or single vertical at centroid-of-flow sampling methods. Select and sample the site to minimize bias. You must create a site file and field folder for each sampling location. After sampling is complete, ensure the data must be inputted into the NWIS files and reviewed for accuracy by a second or third party. These techniques can be used for streams, canals, ditches, flumes, reservoirs, estuaries, lakes, ponds, swamps, marshes and riverine backwaters.

Ground Water

• Ground-water sampling is used for aquifer conditions such as wells. These standards include site reconnaissance, establishment of site files, avoiding bad samples and ground-water withdrawal steps up to the bottling and processing stage. Well construction, deterioration, aquifer media, pumping rate, structural integrity, location as well as air and water circulation must all be evaluated to determine whether water samples from the well are representative of the area. This type of water is vulnerable to contamination from standing borehole water, atmospheric and dissolved gases and well-bottom detritus.

Quality

• Quality control standards for the collection and analysis of water samples are components of the USGS field studies. Evaluate quality in all areas to include identification, quantity, variability, processing, shipping and handling of samples. Each stage of the process includes quality control methods, including washing and preparation of equipment and the use of clean equipment and hands during sampling and processing.