Mimmshall Brook

Rising from two sources—one in Hertsmere, Hertfordshire, and the other in Arkley, London Borough of Barnet—the brook drains into a catchment area of 52 km2 (20 sq mi) at Water End Swallow Holes, Welham Green, North Mymms.

The Mimmshall Brook rises from two sources—Saffron Green Meadows in the borough of Hertsmere, Hertfordshire, and near Arkley Lane and Pastures in Arkley in the London Borough of Barnet.

From there, Mimmshall Brook flows a northeasterly course until Dyrham Park, when it turns north.

From here, the Mimmshall Brook flows through Wash Lane Common in the civil parish of South Mimms.

It then receives the waters of Potters Bar Brook at Mymms Hall Livery Stables, before draining into a catchment area of 52 km2 (20 sq mi) at Water End Swallow Holes, Welham Green, North Mymms.