|The Stream a tributary of the Offwell brook runs approximately
north to south through the reserve and feeds water into some of the most sensitive aquatic
habitats at the Centre. The Offwell brook discharges into the river Coly which flows
into the Axe. The Axe enters the sea at Axmouth.
The stream enters the northernmost end
of the reserve at Monument Pond. The flow of the Stream
through the rest of the reserve is controlled by a sluice gate at one of the two outlets
to this pond. Stopping the flow of flood water into the stream can help prevent the
rapid siltation of the ponds and lakes further to the south.
The flood water is diverted by closing the sluice and forcing the water over a spillway
and into a restored leat, safely away from the Wetland, Kingfisher Pond and the Lake. The stream is mainly shallow, fast moving and gravel or
stone bottomed. This means that in general the stream water will hold more
dissolved oxygen than that in the still water lake and ponds, so supporting different
numbers of invertebrate species in comparison.