Looking WNW from 27th St. Bridge over McAlpine Locks.
<p>"Person" in 360-foot lock, using propwash to flush away sediment before
retrieving old dam wickets from bottom of lock where they have been
stored to keep them wet. 
K&amp;I Bridge in distance.
</p><p>This lock has a long history. Designed by Theodore Scowden (who also designed the Zorn Ave. waterworks), it was opened to traffic in 1872. Originally it was a 2-chamber lock. Each chamber was 350x80 feet and lifted boats 13 feet, with a combined lift of 26 feet. When the 600-foot lock was opened in 1921, the Scowden Locks became auxiliary, but by 1930, they had decayed to the point where a rebuild was required. The lower chamber was rebuilt into a single 360x56 foot lock with a 37-foot lift, enough to accommodate the newly-raised pool above the dam, and the upper chamber became an entrance bay. In 1970, a towboat and barge were in the chamber when the lower gates collapsed. By this time, the 1200-foot lock had been built, so this small lock was no longer needed. A permanent bulkhead was placed across the upper entrance to the lock and it was decommissioned. In this photo, the "Person" is in what was once the 80-foot wide upper chamber, and one can see how the lock wall tapers down to 56 feet wide at the upper end of the lower chamber. Some of the original Scowden Locks stonework can be seen in left foreground.
(from Leland R. Johnson and Charles E. Parrish, <i>Triumph at the Falls: The Louisville and Portland Canal</i>)
See a <a rel="nofollow" class="external text" href="http://www.lrl.usace.army.mil/poi/article.asp?id=590&amp;MyCategory=285">brief illustrated history of McAlpine locks and dam (PDF)</a>
See also a <a rel="nofollow" class="external text" href="https://www.flickr.com/photos/bill_alden/6757383883/in/photostream">detail of a 1932 chart showing Lock 41 and vicinity</a> (the locks and dam were named for William McAlpine in 1960).
</p><p>Ohio River mile 607.
Louisville, Ky..
18-Mar-1999.
99c041.
.
.
</p>
Fuji NPS160 (exposed at 100 ASA), 6x9 cm, Epson V500, Vuescan, medium infrared clean.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/70020260@N04">William Alden</a> from Louisville, Kentucky, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/bill_alden/6692312595/">99c041_8mp: Person in auxiliary lock at McAlpine</a>