Hydro-ecological relations in the Delta Waters

Table 5 gives estimtes of the phosphate load originating from the most
important sources in 1987 and 1988.
The difference between the two years for the Volkerak sluices is caused
by the extra amount of water needed to desalipFEe the lake in 1987.
MW& less phosphate was brought in by the Brabat rivers in 1988 because
in May 1988 the effluent from the sewage Ereatwent plant at Bred&
Nieuweer, was diverted from the Dintel to the Holland6 Diep. When, in
the future, water is extracted from tbe lake for agriculture, the
phasphate load will be higher hficause more water viz1 have to be
sdmirted via the Volkerak sluiees.
The phosphate load in the Volkerak-Zoom lake system could be reduced
by:
- diverting water from the Nieuwveer sewage treatment plant from the
Dintel to the nollands Diep (this wes done in Bay 1988);
- the Rhine Action Plan (RAP);
- the North Sea Action Plan (NAP);
- optiolizing the intake from:
t water losees from locks;
* agriculture;
- treating intake water;
- rsducing agricultural emission*;
- reaching agreement with Belgium on the reduction of the load in the
Belgian part of the Dintel catchment;
- drastic dephosphatiuation sewage treatment plants.
It is expected that the implementation of the Rhine Action Plan and the
North Sea Action Pla will result in a halving of the phosphate load in
the Volkerak-Zoom lake system too. However, this will nor happen before
1993.
If the almve-mentioned measures are implemented vigorously. it seems
possible that phosphate limitation for algal growth could be achieved
in the medium term; in the short term thb is not expected.