Four Locks (holding basin to Lock 49) on the C&amp;O Canal, on Four Locks Road, Maryland. Lock #49 has a spillway to release excess water from the upper canal.
<a href="//commons.wikimedia.org/wiki/User:Chris_Light" title="User:Chris Light">Chris Light</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>