The stream comprises two main tributaries totalling just over 13km of
waterway; of this total length 5.7km is culverted and 7.5m is open
It has a drainage catchment of some 14km²,
about 70% of which lies within the Borough of Poole.
the upper reaches, the catchment boundaries are approximately defined by
Ringwood Road to the west, Wallisdown Road to the north and Ashley
Road/Poole Road to the south. In the lower reaches, the catchment
width gradually narrows towards the outfall in Poole Bay.
overall fall between the highest levels in the upper catchment to the
Poole Bay outfall is approx. 60m, giving an overall gradient of approx.
1:100 which is considered to be steep. The total extent of
industrial development in relation to residential development is small,
and is typically light industry.
geology of the catchment area consists of Eocene marine beds
referred to as the Poole Formation (formerly known as Bagshot
Beds); these are largely sands with seams of pebbles and clay
overlain with gravels high up the valley.
majority of the upper and middle catchment is of national and international
importance, designated in 1985 as a Site of Special
Scientific Interest (SSSI).
It is also a component of the Dorset Heathlands Special Protection Area (SPA),
site (internationally important wetland), and candidate SAC due to its
heathland flora and fauna which supports all six British
reptiles, including the endangered Sand Lizard and Smooth
lower catchment is of high amenity value with public access to the formal English
Heritage Grade II* listed
Bournemouth Pier bathing beach. A number of improvements have been
introduced to the stream here, including the introduction of weirs to
improve aeration, channel improvements and the encouragement of a
wetland habitat area.