Effects of Saline Flushing to a Polluted Estuary to Enhance Water Quality Standards

Abstract

Kananook Creek, a polluted estuary in urban Victoria,was monitored for water quality data over a seven year period. Prior to saline flushing, low species diversity dominated by high numbers of organic pollution-tolerant macroinvertebrates, phytoplankton blooms and cyanobacterial mats occurred throughout the estuary in clearly defined zones. Low dissolved oxygen levels restricted fish movement. Sand and silt deposition in the estuary prevented submergent aquatic plant colonisation, primarily as a result of the unstable, shifting nature of the substratum. Subsequent saline flushing at a maximum continuous rate of 150 ML/day saltwater from a coastal waterway improved quality within the water column of the polluted estuary. Although flushing reduced the incidence of fresh-water species, estuarine fauna and flora rapidly colonised much of Kananook Creek. The incidence of phytoplankton blooms, water discolouration and odour was reduced to the benefit of recreation demands placed upon the creek. Polluted and unstable sediments continued to restrict macroinvertebrate establishment and occasional cessation in flushing for pump maintenance caused a rapid deterioration in water quality.