"PL 97-137, passed by the U.S. Congress in 1982, designated the fossil beds and falls area as 'The Falls of the Ohio National Wildlife Conservation Area.'"
The Falls of the Ohio is one of the largest naturally exposed Devonian Fossil Beds in the world. The “Falls” is in fact not one waterfall, but a series of rapids, which prior to construction of the various locks and dams, dropped 26 feet in about 3 miles, forming a series of rapids, waterfalls, and chutes. Now, the drop in elevation occurs entirely at the lock and dam structures. The normal upper and lower water levels are 37 feet apart; the normal upper pool elevation is 420 feet above mean sea level and the lower pool is 383 feet above mean sea level. The area has a rich cultural and natural history. The area was used as a crossing point for animals, and as a hunting area for Native Americans. More than 260 bird species have been sighted at the Falls, and a wide variety of other wildlife is present. In the river’s natural state, boats could traverse the falls during periods of high water only, so the area became a stopping point while goods were unloaded and portaged, thus creating the towns of Louisville, Clarksville and Jeffersonville. When there was enough water, boats could attempt to run one of three chutes, or passages through the Falls, but this required expertise and boats often wrecked during the attempt. In 1830, the 1.9 mile privately owned and operated Portland Canal with a 3 flight lock at the lower end was finished. By 1930, a new concrete and steel dam was built in conjunction with a hydroelectric plant project of the LG&E company. The dam was constructed in an “L” shape, extending from the Indiana shore and gave the Falls area its present look. See the webpage for McAlpine Locks and Dam for more history on the locks and dam. [Their link is broken. Try this one.] [USACE-recreation, expand the History heading]I would call the Dam a Z shape. I marked up a satellite image to show the powerhouse and downstream control gates (red), the 2-mile fixed weir (orange), and the upstream control gates (blue).
|Satellite plus Paint|
This Z configuration is expensive because of the 2-mile fixed weir, but the two sets of control gates allow the USACE to emulate traditional summer-time flows (low) over the rapids by closing the five upstream gates and using the hydroelectric plant and the four lower gates to control the upper-pool depth. During the Spring and Fall wet seasons, it can give the upper gates priority to be open to maintain a strong flow across the rapids. This seasonal variance of the river flow helps preserve the wildlife that was established when the level of the river naturally varied significantly during the year. And it allows fossil viewing during the dry season.
See Louisville & Indiana/CSX/Pennsy Bridge for more photos of the upstream control structure.
Standing on the visitor's center viewing platform, I took a sequence of three photos from upstream (Southeast) to downstream (Northwest) to catch the weir wall and rapids.
|Gimp brightness +35, contrast +10|
But first I had to work my way over the debris field.
But it was far enough out into the river bed to let me get a good view of the five Tainter gates (below). Note the water turbulence around the through-truss pier. It is a good thing it is built on rock. Even so, it is amazing that it has been able to avoid scouring after decades of turbulent flow around it. It does look like they have sheathed the base with a protective layer of concrete.
One of 30 photos in Courier-Journal (countware) concerning the allision of barges with the upper control structure.
High Water Images
|Photo by Joe Virruso via Bridge Hunter|
[Note that the Tainter gates are raised all the way and are practically parallel to the surface of the water.]
|Bill Kalkman posted|
In this view from the shoreline of the Ohio River, below the Falls of the Ohio Interpretive Center, your looking at the Louisville & Indiana Railroad's crossing of the river from Clarksville to Louisville. 6:52PM on 5-23-18 in Clarksville, IN.
Note how one photo taken by Andrew Raker in April, 2014, shows the lower pool at an intermediate level, but another photo by Andrew that same month shows the lower pool at a high level. And it was even higher in May, 2014.
[In this view, you can see the Tainter gates are completely open. And the river is high enough that it is almost covering the dam walls.]
|From the Wildlife Conservation sign|
Low Water Images
Bridge Hunter photos taken by James Adorno in June, 2005; Robert Thompson in July, 2005; Ed Hollowell in July, 2005; and Andrew Raker in September, and December of 2013, in August, 2011, in September, 2009, in June, July, August and October of 2008, and in September, 2007.
|From the rest stop sign|
|From the Wildlife Conservation sign|
[This picture taught me that they can create a low flow over the fossil beds during the Summer even if the river has a high flow by shutting the upper gates and opening the lower gates.]
|Satellite, the upper gates are almost closed and the base of the dam wall is exposed|
|Satellite, while all of the lower gates are open|