HECO annually conducts and reports results of a biological monitoring program for waters receiving effluent from the Kahe Generating Station, O'ahu, Hawai'i from 1992 to 1997 (NCEI Accession 9900021)

Since January 1, 1986, HECO has used adjusted intake water temperatures as the reference against which temperature elevations of the thermal effluent are measured. Intake temperatures are adjusted downward by 0.42 C to determine the reference temperature. Based on over 10 years of temperature records collected at an ambient temperature control station, it was determined that intake temperatures exceeded nearshore ambient bottom temperatures by this amount.

Daily records were kept of maximum, minimum, mean effluent, and mean influent temperatures. Intake and discharge temperatures were recorded continuously using a Foxboro ERB strip chart recorder and Dynatherm resistance bulbs. The intake temperature resistance bulb is located in Unit 1-4 forebay and the discharge temperature resistance bulb is located in the transition basin before the discharge pipe.

The present ambient temperature collection method provides a sensitive and readily available range from which temperature elevations of the effluent above ambient can be compared.