The cost of cleaning the bay

The chemical compounds in question are nitrates, the department seeking the advice of the Crown Officers is Environment, and the potential law-breaker is Transport and Technical Services.

Many people will be aware that nitrates have led to controversy in the past, when fertiliser applied to farmland appears to have increased their concentration in the Island’s water supply.

Now, however, the principal concern relates to the content of the treated effluent which flows from the treatment plant at Bellozanne into St Aubin’s Bay. Although treatment means that, in ordinary circumstances, the vast majority of bacteria and viruses are eliminated from the effluent, its nitrate concentration is, apparently, above the maximum level considered to be acceptable under standards set by Europe.

In contrast to microbes, nitrates in the effluent discharged from the outfall on the beach near First Tower pose no direct threat to human health. But, unfortunately, they are capable of producing effects detrimental to the ecology of the bay and the quality of the environment.

It is thought that high concentrations of nitrate in shallow coastal waters can lead to the proliferation of marine algae which in some circumstances can overwhelm other forms of life. The alga that seems to thrive in the vicinity of the First Tower outfall is, as we are all too aware, sea lettuce, which is washed up in spring and summer to form slimy, smelly masses.

Transport and Technical Services clear away the decaying sea lettuce before it ever produces dangerous concentrations of the ‘bad eggs’ gas hydrogen sulphide, but the problem is nevertheless acute enough to inconvenience tourists and those who live at the margins of the bay.

It is now possible that Transport, the department responsible for the Bellozanne plant and the outfall, will be forced by law to clean up the nitrate act. But, inconveniently, the department might not be well placed to comply with instructions to stop breaking the law, having already spent £8 million on denitrification technology that has failed to deliver results.

In addition to witnessing fines imposed on an arm of government, we might well see further demands made on the public purse if Transport press for a once-and-for-all solution to the nitrate problem – an outfall which discharges into deep water, where the effluent would be rapidly diluted by strong tidal flows.