Water quality and aquatic fauna associated with ditching systems dug in 1968 and in 1972 in an irregularly flooded marsh were studied. Salinity, pH, temperature, dissolved oxygen, were determined monthly. Dissolved oxygen was lowest at the upper ends of the ditches. Organic matter seemed to have been built up at the upper ends ofthe ditches due to inadequate tidal flushing. Mats of submersed vegetation hindered tidal flow which reduced the flushing effectiveness of the tides. Water quality differences between the upper and lower portions of the ditches seemed to be physical rather titan biological. Organisms collected were typical estuarine species. There were no significant benefits from the ditches other than to control mosquitoes.