The Bourne Stream flows for approximately 7km from the outskirts of Canford Heath in Poole, to the bathing beach at Bournemouth Pier.

It has a catchment area of approximately 14km^2.

It is formed of two main tributaries, the total length of waterway being 13.2km.

5.7km of this total length is culverted, and 7.5km open stream; 3.1km of culverting has been created since 1949.

There are 62 recorded piped discharges to the stream between Ringwood Road and Lower Gardens; that's one for every 21m of stream.  The vast majority of them carry surface water drainage from the catchment, each of them a potential source of pollutants to the stream.

Bournemouth Water (established 1863, now Bournemouth & West Hampshire Water) once abstracted raw water from the Bourne Valley for potable supply to the growing resort town.  This practice ceased early in the 20th Century due to "the water being subject to occasional odours and discolouration" (BWHW, 1988).

The stream discharges at Pier Approach, Bournemouth.  During dry weather it enters the combined storm overflow from Bournemouth No.1 Pumping Station.  During heavy rainfall it's diverted over a weir into the short concrete outfall to the east of Bournemouth Pier.

The culvert at Bournemouth Pier measures 104 metres from the weir.

The outfall at Bournemouth Pier comprises two foul water discharge pipes - (1) 1067mm diameter x 587 metres long, and (2) 1219mm diameter x 671 metres long, both measured from the headworks weir.

The stream's only purpose-built gauging weir is at Branksome Wood Road; it was constructed by Bournemouth Council's Drainage and Coast Protection Team in 1995/1996 at a cost of £53,750 which included works to the stream banks, the provision of a new timber footbridge and channel realignment works.

From the design calculations and projections, the gauging weir is designed for a maximum discharge of 4.4 cu.m./second which gives a head of 0.85m above the crest of the weir (read about stream hydrology).

During heavy rainfall events stream flows can escalate from 40 to 1,800 litres per second – that’s a 4500% increase on normal volume.  This increase in flow was measured at the Branksome Wood Road gauging weir between 11:00 and 17:15 on 22^nd October 2003, the wettest day of 2003 when 34.9mm of rain fell in 24 hours (read about local rainfall).

Water Voles - Dorset Wildlife Trust water vole survey: