Summary statistics and trend analysis of water-quality data at sites in the Gila River basin, New Mexico and Arizona

Abstract

Chemical concentration and water temperature are given only in metric units. Chemical concentration in water is given in milligrams per liter (mg/L) or micrograms per liter (ug/L). Milligrams per liter is a unit expressing the solute per unit volume (liter) of water. One thousand micrograms per liter is equivalent to 1 milligram per liter. For concentrations less than 7,000 milligrams per liter, the numerical value is about the same as for concentrations in parts per million. Specific conductance is given in microsiemens per centimeter (uS/cm) at 25 C. Dissolved In this report, the term "dissolved" refers to constituents in a representative water sample that pass through a 0.45-micrometer membrane filter or a 0.7-micrometer glass fiber filter for organic analysis. Determinations of dissolved constituents are made on subsamples of the filtrate. Whole water, recoverable The term "total" used in this report means "whole water, recoverable," which refers to constituents in solution after a representative water-suspended-sediment sample is digested (usually using a dilute acid solution). Complete dissolution of paniculate matter often is not achieved by the digestion treatment, and thus the determination represents something less than the "total" amount (that is, less than 95 percent) of the constituent present in the dissolved and suspended phases of the sample. For inorganic determinations, digestions are performed in the original sample container to ensure digestion of material absorbed on the container walls. To achieve comparability of analytical data, equivalent digestion procedures would be required of all laboratories performing such analyses because different digestion procedures are likely to produce different analytical results. VERTICAL DATUM Sea level: In this report, "sea level" refers to the National Geodetic Vertical Datum of 1929 A geodetic datum derived from a general adjustment of the first-order level nets of the United States and Canada, formerly called "Sea Level Datum of 1929." Contents V