English: This is a river lock at 30.64 miles, just before Edwards Ferry, to allow boats from Goose Creek to enter the canal. This is the opening to the Potomac River. Unlike most locks, this is a staircase lock, i.e. 2 or more locks together with no intervening level between them (like that at Lockport, NY on the Erie), This means the top gate of the lower lock is the same as the bottom gate on the upper lock. It is the only staircase lock on the Chesapeake and Ohio Canal. NPS site (http://www.hscl.cr.nps.gov/insidenps/report.asp?STATE=&PARK=CHOH&STRUCTURE=&SORT=&RECORDNO=218) says: Goose Creek River lock was built to allow boats from the VA side of the Potomac River to access the canal. The lock is a 2-lift lock combine with a total lift of 15’, joined by a middle set of gates. Each lock is approx 90' long. Built of Seneca red sandstone with Aquia freestone coping, it was completed by 1838. Around 1900 it was no longer used as a lock, but as a wasteweir for the canal. A new concrete wasteweir of four gates was built adjacent to the upstream side of the upper lock gate. This new wasteweir meant that boats could no longer travel from the river locks into the canal prism.