Technical Report No. 35
EFFECTS OF SURFACE RUNOFF AND WASTE DISCHARGE INTO THE SOUTHERN SECTOR OF KANEOHE BAY: JANUARY – APRIL 1968
Edison L. Quan, Reginald H. F. Young, Nathan C. Burbank, Jr., L. Stephen Lau
January 1970
ABSTRACT
A study of the surface water quality in the southeastern portion of Kaneohe Bay was undertaken between February and mid-April, 1968. The aims of this project were to determine: (1) the effect of surface runoff on water quality in the Bay, (2) the chemical and bacterial content of wastewaters emerging from two sewage treatment plant outfalls, and (3) whether the overall water quality standards were met. High rainfall and subsequent high surface runoff introduce high concentrations of nitrate-nitrogen and fecal streptococci into the lower reaches of Keaahala and Kaneohe streams. High concentrations of fecal streptococci also occur in waters overlying a clam bed during high stream flows, suggesting that a potential public health hazard may exist during the rainy period. High land runoff lowers the water temperature by 2oC, over dry weather flow and causes silt turbidity along the nearshore waters in the Bay. Phosphate-phosphorus concentrations in the Bay waters at the location of waste discharge averaged 0.046 mg/l for the Kaneohe sewage treatment plant and 0.033 mg/l for the Kaneohe Marine Corps Air Station sewage treatment plant, exceeding the limit established for Class A waters by 0.021 and 0.008 mg/l, respectively. Surface runoff is not a significant contributor of phosphates into the Bay compared to the sewage waste discharge. In general, the dissolved oxygen content and pH adequately met the water quality standards at all stations except for two low dissolved oxygen readings in Keaahala Stream. From mid-bay to the northern portion of the Bay, the parameters utilized indicated that the overall water quality met the standards established for both Class AA and A waters.