The investigation reports the results of a historical data collection of information concerning the lower Ashtabula River, Harbor and nearshore area, a detailed water sampling and biota collection made during 1973 and 1974, and an evaluation of present and future discharges on the water quality and biota of the area. The quality of water passing through the Ashtabula complex including Fields Brook has been recognized for many years as a serious environmental problem. Total residual chlorine, mercury, dissolved solids, and metals content appear to be the most serious water quality parameters which affect this area. Measurement of these parameters from the harbor to Fields Brook demonstrate the source of the materials. Flushing time calculations for Ashtabula Harbor during low flow conditions indicated near stagnation for late summer. Diatoms and phytoplankton recovered in the harbor and lower river indicated the presence of a eutrophic, pollution tolerant type of community. Continued monitoring of the total residual chlorine, mercury, conductivity and dissolved solids during the next two years is recommended.