Years of laissez-faire development led to damaging floods, mounds of construction waste and polluted water in the basin which serves a burgeoning population that grows increasingly dependent the source. The plan, a joint venture between Moriyama & Teshima Planners Limited and Buro Happold was to turn the basin into a thriving natural reserve that not only would restore wildlife, but serve to provide benefits for the community. Water quality was paramount in the restoration for both the water upstream and for the city’s wastewater which is intended to be stored and reused. To accomplish this 1.25 million cubic meters of construction debris were removed, and the haphazard roads and power lines were reorganized to reduce surface impact. Side water inlets have been reclaimed or added to aid in flood control and habitation.
Situated adjacent to the city, the basin is a major local and tourist attraction thus recreational facilities were combined with habitat enhancement and water quality infrastructure. Natural stone weirs were installed to create a habitat for micro-organisms as well as to increase oxygen levels to reduce chloroform bacteria. The large bio-remediation facility is a one of a kind design which recreates a complex habitat, in turn treating the city and river water naturally. Downstream large Periphyton Benthic Substrate Devices (APBS) have been installed, which have given way to an underwater habitat.