Not one size fits all
Loads introduced to rivers vary considerably. In extreme wet weather, contributions from intermittent and rainfall-generated runoff can increase relative to continuous discharges operating in both dry and normal wet weather conditions. In recognition of this, spill frequency standards have been developed to protect the status of estuarine and coastal designated bathing waters; an average of either 2 or 3 spills per bathing season is permitted for either Excellent or Sufficient/ Good waters.
The primary question to be addressed for the EA was whether the 3 (or 2) spill frequency design standard applied to estuarine and coastal bathing waters is also appropriate to riverine bathing waters, given the different factors that arise relating to intermittent discharges.