Operational Procedures for Collecting Water-Quality Samples at Monitoring
Sites on Maple Creek Near Nickerson and the Platte River at Louisville, Eastern
Steven M. Johnson and Robert B. Swanson
Open File Report 94-121
Prototype stream-monitoring sites were operated during part of 1992 in the Central Nebraska Basins and three other study areas of the National Water-Quality Assessment Program of the U.S. Geological Survey. Results from the prototype project will provide information needed to operate a network of intensive fixed-station stream-monitoring sites.
This report evaluates operating procedures for two National Water-Quality Assessment prototype sites in the Central Nebraska Basins study area at Maple Creek near Nickerson and the Platter River at Louisville, Nebraska. Each site was sampled intensively in the spring and late summer 1992, with less intensive sampling in midsummer. In addition, multiple samples were collected during two high flows at the Maple Creek site-one early and the other late in the growing season. Water-sample analyses included determination of pesticides, nutrients, major ions, suspended sediment, and measurement of physical properties. Equipment and protocols for the water-quality sampling procedures were evaluated.
High-flow stream sampling was difficult to complete because of unpredictable precipitation and its resulting storm runoff. The tracking of storms and anticipation of high flow required extra effort by personnel to collect water samples at selected stages of flow. Some equipment and procedural modifications were found to improve collections and processing of water samples.
Operation of the prototype stream-monitoring sites included development and comparison of onsite and laboratory sample-processing procedures. Onsite processing was labor intensive but allowed for immediate preservation of all sampled constituents. Laboratory processing required less field labor and decreased the risk of contamination, but allowed for no immediate preservation of the samples.