From the Wikipedia page 
The Silk Stream is a tributary of the River Brent, which it joins at Brent Reservoir. It has several tributaries including Burnt Oak Brook, Edgware Brook, the Edgwarebury Brook and Deans Brook. The Silk Stream runs north-south through Colindale and Hendon. It gives its name to Silkstream Road, near Burnt Oak Station.
Silk Stream and Burnt Oak Brook are a Local Nature Reserve, Borough Grade II