|
 1992:
Wessex Water instigated biological surveys of the stream and the
ponds within it; results indicated poor water quality in both,
supporting low levels of macro-invertebrates
(Wessex Scientific, 1992);
1993-1994:
further studies by Wessex Water highlighted probable causes of
pollution as run-off from urban areas and gully pots
 1993-1995:
following their own investigations, Bournemouth Borough Council
presented data that confirmed there was a correlation between
rainfall events and elevated faecal coliform counts in the stream
(Environment Agency, 1996/1997);
 1995:
the Environment Agency (EA) carried out more detailed studies
close to Bournemouth Pier during the bathing water season and drew a
probable link between rainfall events and water quality problems at the designated
bathing beach west of the Pier (National Grid Reference SZ 408850
90650) (Environment Agency, 1996/1997);
A
stream is often capable of diffusing the high levels of bacteria
associated with a first flush event, but the Bourne Stream's
normal flow is relatively low so does little to dilute
pollutants. It runs
only 7km from it's source to the beach at Bournemouth Pier and its
course is steep and relatively narrow, giving
very little time for water quality to improve before it discharges
into Poole Bay.
In
order to minimise the impact of the Bourne stream on local bathing
waters, it was concluded by the EA report (1996/1997) that it
would be necessary to apply Best
Management Practices (BMPs) to the catchment to improve
bacterial levels in the Bourne stream.
1998:
Consulting Engineers, Peter
Brett Associates (PBA), was contracted by the Environment Agency to produce a
Scoping Study for Surface Water Run-off Best Management Practices (BMPs) in the
catchment.
1999:
the report
put forward possible in-stream structures, such as ponds and infiltration
ditches to increase retention time and provide treatment to improve water
quality.
2000:
realising that no one single
agency could tackle these issues alone, the EA set about forming
the Bourne Stream Partnership to take forward the BMPs suggested
by PBA.
The use of BMPs (now more widely known as Sustainable Urban
Drainage Systems, or SUDS) is common in Europe and North America
and becoming increasingly widespread
in the UK.
Notes:
(i)
a lottery grant application for the construction of a new long sea
outfall to accommodate the flow from the Bourne stream at all
times was unsuccessful;
(ii)
Wessex
Water have undertaken improvements to increase storage capacity at
Bournemouth No 1 Pumping Station and reduce the frequency with
which the stream discharges via the short sea outfall (from
approx. 20 to approx. 3 times per year). |
Background