5.4. 3: Managing Eutrophication
Lago Paranoa Case Study
Lago Paranoá (4,000 ha, 14 m mean depth) is an urban man-made lake created in 1959 to improve leisure and climate conditions, as well as to receive wastewater and run-off from the new capital of Brazil, Brasilia.
Lago Paranoa in Brasillia, Brazil is a man made lake created to handle increased waste water and run-off from the Brazilian capital. Lago Paranoa which was constructed in 1959 has a surface area of around 4,000 ha. By the 1970’s increased discharge of untreated sewage directly into the lake from two sewage plants was causing severe Eutrophication. The problems came to a head in 1978 with a major bloom of toxic algae in reservoir killing many fish and creating a major odor problem in the city as the fish decomposed.
Lago Paranoa Today Source:www.universonautico.com.br
Over a twenty year period from the mid 1970’s a multi-million dollar effort was made to reduce the eutropication in Lago Paranoa. Various National and International agencies including the Brazilian Government the UN and international Investment Banks oversaw various projects including training local staff to monitor water quality in the lack. Building two new sewage treatment plants to deal with waste effectively and building new sewage pipelines to handle the waste. As well as dealing with the abiotic causes other projects have involved managing fish numbers to improve water quality and flushing out toxic bacteria at the end of the dry season.
The management program has resulted in the re-creation of a safe water body that is now capable of being used for swimming and recreation and again has sustainable fish stocks.
Case study based on Restoration of a tropical urban reservoir: Lago Parano< (BrasRlia, Brazil)