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Posted 10/3/2012

Release no. 12-010


by Little Rock District Public Affairs

Montgomery Point Lock and Dam Ensures System Available During Low-Water Conditions

LITTLE ROCK, Ark.-- During this year’s unseasonably dry summer the McClellan-Kerr Arkansas River Navigation System functioned as designed ensuring a 9-foot channel for barge traffic moving through the system.

Because water levels on the Mississippi River dropped so low the crest gates at Montgomery Point Lock were used this summer for the first time since 2008.

Located on the lower section of the MKARNS near Tichnor, Ark. Montgomery Point Lock and Dam was put into service in 2004, solving the low-water problem in the area by eliminating the recurrent navigation restrictions and reducing dredging needs by more than 90 percent.

When the Mississippi River water levels start getting low the White River, which flow into the Mississippi, drops too.

Montgomery Point Lock and Dam features "first of its kind" hydraulically operated gates. When the tail water is at elevation 115 and rising, the dam gates are flat on the bottom of the river and barge traffic passes over the gates in the navigation pass spillway to minimize lockages saving time and money.

When the tail water is at elevation 115 and projected to fall, the 10 dam gates are raised to ensure a 9-foot pool behind the dam which forces barge traffic through the lock instead of over the gates.

It took many years of planning and construction to complete Montgomery Point Lock and Dam. However, if it had not been built, millions of dollars would have been spent on dredging the lower end of MKARNS to ensure the channel stayed open during dry weather years.

The design of Montgomery Point makes positioning the gates less labor-intensive for the lock operations crews, because all gate changes can be completed with the push of a button. The design also has most of the operating equipment housed in the gallery to keep it dry which cuts down on the damage due to weathering.

Another noteworthy design feature is that the entire lock and dam, except for the control tower is completely below the top banks of the channel. During very high water conditions, the structure is submerged, except for the control tower. Because of its location, the project was designed to withstand large fluctuations in the water surface elevation. The water surface at Montgomery Point has fluctuated from elevation 104 to 172.

Although the design is rarely used it paid off this summer by keeping the MKARNS flowing and the economy going. The same cannot be said for many of the Midwestern state’s river and streams.

dam Little Rock lock Montgomery Point