The Old Garston River or Garston River, sometimes referred to as the Garston Brook, is a tributary of the River Mersey in Garston, Merseyside, a district of Liverpool. Having been encroached upon by urban development, it is now a subterranean river, culverted for all of its length, although unlike many culverted urban rivers it has not been incorporated into the sewer system. Due to a low capacity of its culvert, the Old Garston River still presents an occasional flooding risk and is thought to be responsible for flooding at Woolton Golf Course and other nearby sites.