Harmonic equations were developed to describe stream temperatures at 144 sites in New Mexico using periodically observed water temperatures collected from October 1964 through September 1969. The harmonic equations explained at least 80 percent of the variability at 70 of the sites. Standard errors of estimate ranged from 1.3 to 5.4 degrees Celsius and averaged 3.1 degrees Celsius. Stream-temperature characteristics are defined in terms of the mean, amplitude, and phase coefficients of the harmonic equations. The characteristics vary widely throughout the State, hence are described areally by regionalized regression equations. Regional equations developed to describe the mean temperature characteristic accounted for at least 84 percent of the variability and had standard errors of estimate less than 13 percent. Only one equation was adequate for describing the amplitude. That equation was for streams having drainage areas less than 2,500 square miles and in the northwestern part of the State. No equation was developed for the phase coefficient. Stream-temperature characteristic profiles are used to describe the trends of the three characteristics along major streams. (Woodard-USGS)
