Storm runoff water-quality samples were collected as part of the State of Hawaii Department of Transportation Stormwater Monitoring Program. This program is designed to assess the effects of highway runoff and urban runoff on Halawa Stream. For this program, rainfall data was collected at two sites, continuous streamflow data at three sites, and water-quality data at five sites, which include the three streamflow sites. This report summarizes rainfall, streamflow, and water-quality data collected between July 1, 2002 to June 30, 2003.
A total of 28 samples were collected over five storms during July 1, 2002 to June 30, 2003. For two of the five storms, five grab samples and three flow-weighted timecomposite samples were collected. Grab samples were collected nearly simultaneously at all five sites, and flow-weighted timecomposite samples were collected at the three sites equipped with automatic samplers. The other three storms were partially sampled, where only flow-weighted time-composite samples were collected and/or not all stations were sampled. Samples were analyzed for total suspended solids, total dissolved solids, nutrients, chemical oxygen demand, and selected trace metals (cadmium, copper, lead, and zinc). Grab samples were additionally analyzed for oil and grease, total petroleum hydrocarbons, fecal coliform, and biological oxygen demand. Quality-assurance/qualitycontrol samples, collected during storms and during routine maintenance, were also collected to verify analytical procedures and insure proper cleaning of equipment.
