Eighteen wells and seven surface water stations were sampled in May, August, and December 1995. Field measurements of water temperature, pH, and specific conductance were also made. The depth to ground water is shallow, ranging from as little as one foot to 29 feet below ground surface. Although ground water interacts with Quilceda Creek throughout its length, ground water recharge from precipitation is greatest in the northern portion of the study area and ground water discharge to Quilceda Creek is greatest in the southern portion. Fecal coliform bacteria appear to be primarily a surface water problem.
Bacteria entering the creek are probably from non-point sources near the stream channel.
Ground water is an important source of TDS, nitrate and chloride to Quilceda Creek as well as a minor source of TOC, ammonium, and phosphorus.