Hartbeespoort Dam, South Africa
The Hartbeespoort Dam is located 37
km west of South Africa's capital city, Pretoria and is surrounded
by a number of very affluent residential areas. It is
classified as hypertrophic and is heavily loaded with nutrients
which have entered the dam due to runoff from fertilized fields and
the inflow of sewage plant effluents from the northern suburbs of
Johannesburg. For most of the year, the dam is dominated by
dense populations of cyanobacteria, or blue green algae.
One of the earliest Phoslock trials
was undertaken on a 2.5 hectare man-made bay at K'shani Lake Lodge,
a housing development on the western side of the dam. The
site had an average depth of 3m and was connected to the main dam
through an opening of 8m. This was blocked off with floating
logs and a tarpaulin weighed down with chains. A further area
was blocked off in a similar manner within the test site to serve
as an untreated control area.
Six tonnes of Phoslock were applied
to the bay in January 2006 by the South African licensees and the
treated and control sites were monitored over the following 12
months by the University of Pretoria. The trial resulted in a
clear and sustained reduction in filterable reactive phosphorus in
the treated area over the course of the 12 months in comparison to
the control area. Full details of the trial are available in
the downloadable report.
