Facilities to treat wastewater and dispose of effluent from the Ulkatcho community were installed in 1997 and 1998. Primary and secondary treatment consists of coupled anaerobic and facultative lagoons, while advanced secondary treatment is achieved in a long-term storage lagoon. Natural wetlands downstream of the lagoons provide advanced secondary and tertiary
treatment by removing and/or retaining biochemical oxygen demand, total suspended solids, fecal coliform and nutrients before disposal by discharge into the Dean River. Limnotek is testing the effectiveness of the treatment and disposal system using a multiyear monitoring design to examine water quality through the treatment works and in the Dean River and Anahim Lake that is an enlargement of the Dean River.
Treated wastewater was discharged from the storage lagoon to the wetlands for the first time in 2011. Chemical and biological monitoring within and downstream of the treatment system showed that without holding treated wastewater in wetlands, the treatment works were effective in removing biochemical oxygen demand, fecal coliforms, nitrogen, and phosphorus in water that was discharged to the Dean River. Findings showed that although eutrophication (high nutrient loading leading to high rates of algal production and biomass that can produce poor water quality) of a downstream lake had accelerated from earlier years, nutrient sources other than the discharge from the Ulkatcho wastewater treatment system were most important in contributing to that change. Monitoring in 2012 and 2013 will enable calculation of treatment effectiveness within the treatment system following retention of wastewater in the wetlands and it will show differences in nutrient transport from the treatment system and nutrient transport from sources in the Dean River that are upstream of the confluence of the wetland outflow and the Dean River.