A solid-state Au/Hg voltammetric microelectrode was used to monitor the development of seasonal anoxia in Delaware coastal bays which have deep holes with stratification. Since fish kills and harmful algal blooms have occurred over the years here, water circulators were installed in October 2003 to improve water quality. We conducted in situ determination of temperature, salinity, pH, dissolved O2 and H2S to document the circulators' function which was evaluated by comparing in situ data obtained before and after their installation. Stratification at both sites was similar in 2004 to that in previous years. Furthermore, the circulators did not oxygenate the water column but did bring some H2S to the surface waters. We found that O2 concentrations in the surface waters and H2S concentrations in the bottom waters were similar in different years. Thus, the H2S conditions were not abated and water quality was still a problem.