The Power of Water
By Ranger Curt
As an avid biker, I spend a lot of time on the towpath. In doing so, I often find myself looking out on the Potomac River. Most times of the year and in most places along the canal, the river looks serene and its waters seem to be barely moving. However, as I approach Dam #4 heading upstream from Taylors Landing, I can truly feel its power. The roar of the water over Dam #4 fills the air, and even sends a vibration through the ground. It fills not only the water, but also me, with energy. I get an adrenaline rush every time.
The seven dams on the Potomac River were originally built to divert water into the canal. Dam #4 provided water for 22 miles of the canal, from Milepost 84.6 downstream to Milepost 62.3, just above Harpers Ferry. The water was regulated at the guard lock at Dam #4 to maintain a consistent level of water traveling at two miles per hour down the canal prism.
For the past hundred years Dam #4 has also been capturing the water's power at a facility on the West Virginia side of the river. This hydro-electric gravity dam, built in 1913 and modified in 1994, is 20 feet tall and approximately 800 feet across. It uses a drive belt to transfer power from the river to the turbines. They in turn provide electric power to people in Washington County. True water power!
- The Shawnee Canoe Club took many trips down the C & O Canal on either canoes or packet boats with their family. One of the members peers over the stone wing wall at the rushing water of the Potomac hurdling over Dam 4. Credit: Shawnee Canoe Club Collection, Chesapeake & Ohio Canal National Historical Park
- At Dam 4 sits the stop gate winch house. This is not a covered bridge but a building that held the stop gate that could be lowered down to prevent damaging flood waters to enter the canal and damage the towpath and prism.Credit: Shawnee Canoe Club Collection, Chesapeake & Ohio Canal National Historical Park
- The river lock was used to allow boats traveling on the slackwater behind the dam to reenter the canal. It also acted as the water control structure for the canal downstream. Water would be let into the canal at this point to allow for the use of the locks and boat travel. Credit: F.R. Holland, Chesapeake & Ohio Canal National Historical Park
- View of Dam 4 from the West Virginia side of the Potomac River. Credit: C&O Canal National Historical Park
- Waste Weir upstream from Dam 4 used to regulate the level of water in the C&O Canal. Credit: C&O Canal National Historical Park
- Boat Ramp upstream from Dam 4 provides Potomac River access to the Big Slackwater for modern boaters. Credit: C&O Canal National Historical Park

Dam #4
Milepost

Guard Lock
Milepost 85.8

Stop Gate and Winch House
Milepost 84.6

Hydro-electric Power Plant
Milepost 84.6

Fishing at Dam #4
Milepost 84.6