Cation, anion, conductivity, and absorbance characteristics of Tarawera River seepage water entering the Western Drain, Eastern Bay of Plenty, New Zealand.

Abstract

Two pulp mills, located downstream of the township of Kawerau, in the Eastern Bay of Plenty region of New Zealand, have for more than 35 years, discharged effluent waters to the Tarawera River. Upstream of the mill discharges river water has a high quality, while downstream water is highly coloured and characterised by diminished dissolved oxygen (BOPCC 1985, McIntosh 1995, Rutherford et al. 1991, Rutherford 1991) and by the presence of significant levels of resin acids (Wilkins et al. 1996a, Judd et al. 1996). During its passage across the Western Rangitaiki Plains the Tarawera River is constrained behind stop banks. At two points the river passes in close proximity to the Western Drain. This drain is one of a series of canals and drains which collect water from surrounding farmland and return it to the Tarawera River shortly before its entry to the sea near the township of Matata.