Coeur d' Alene Basin Water-Quality Monitoring
Methods
The USGS samples surface water based on BEMP and associated Quality Assurance Project Plan requirements which reference USGS standard water-quality data collection procedures.
Samples are collected using non-metallic samplers and cross-sectional, depth-integrated sampling procedures. Samples are composited and subsampled using a polyethylene churn splitting device. Samples for total analyses are withdrawn directly from the splitting device. Samples for dissolved (smaller than 0.45 micrometer diameter) analyses are filtered through a 0.45 micrometer pore size, disposable capsule filter. Metal and nutrient samples are preserved with nitric and sulfuric acid, respectively, to a pH of less than 2, chilled to 4 degrees Celsius, and sent to the USGS National Water Quality Laboratory in Denver Colorado
Suspended sediment is collected as a separate cross-sectional, depth-integrated sample or as a subsample from the splitting device. Suspended sediment samples are sent to the USGS Cascades Volcano Observatory Sediment Laboratory in Vancouver Washington
Metals and hardness analyses are performed by inductively-coupled plasma atomic emission spectrometry (ICP-AES) and inductively-coupled plasma mass spectrometry (ICP-MS). Nutrient analyses are performed using conventional USGS analytical procedures and standard EPA methods.
Suspended sediment samples are analyzed for total concentration and sand/silt particle size.
