Chain of Rocks Lock
Encyclopedia
Chain of Rocks Lock, also known as Locks #27, is a lock
situated on the southern end of Chouteau Island
near St. Louis
, Missouri
on the Upper
Mississippi River
. Its associated dam is just downstream of the Chain of Rocks Bridge
and the lock is located over three miles (5 km) south east, on the Chain of Rocks canal bypassing an unnavigable portion of the river.
The 1200 feet (366 m) main lock and 600 feet (183 m) auxiliary lock were built in the late 1940s and early 1950s to allow a by-pass of the Chain of Rocks lying in the main channel of the Mississippi River. This stretch of river in low water seasons was treacherous for commercial tow boats and barges, often requiring them to wait up to several days for the river to rise. Lock 27 is the only lock on the Mississippi River System without a man made dam. Tons of rock were laid in the Mississippi to create a small pool elevation upstream from the Chain of Rocks. The drop at Locks 27 can vary from a few feet to over a ten foot drop depending on the river stage.
The Chain of Rocks Lock is operated by the St. Louis District of the U.S. Army Corps of Engineers. Locks #27 are the southernmost locks on the Mississippi River
and they are the only Locks south of the confluence of the Mississippi River and Missouri River
. As such, the Locks move more cargo than any other navigation structure on the Mississippi River.
Lock (water transport)
A lock is a device for raising and lowering boats between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water level can be varied; whereas in a caisson lock, a boat lift, or on a canal inclined plane, it is...
situated on the southern end of Chouteau Island
Chouteau Island
Chouteau Island , situated approximately due north of the St. Louis, Missouri Gateway Arch and approximately south of the confluence of the Missouri River and Mississippi River, is one of a cluster of three islands: Chouteau, Gabaret, and Mosenthein. The three, with a combined area of...
near St. Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
, Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
on the Upper
Upper Mississippi River
The Upper Mississippi River is the portion of the Mississippi River upstream of Cairo, Illinois, United States. From the headwaters at Lake Itasca, Minnesota, the river flows approximately 2000 kilometers to Cairo, where it is joined by the Ohio River to form the Lower Mississippi...
Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. Its associated dam is just downstream of the Chain of Rocks Bridge
Chain of Rocks Bridge
The Chain of Rocks Bridge spans the Mississippi River on the north edge of St. Louis, Missouri. The eastern end of the bridge is on Chouteau Island, , while the western end is on the Missouri shoreline....
and the lock is located over three miles (5 km) south east, on the Chain of Rocks canal bypassing an unnavigable portion of the river.
The 1200 feet (366 m) main lock and 600 feet (183 m) auxiliary lock were built in the late 1940s and early 1950s to allow a by-pass of the Chain of Rocks lying in the main channel of the Mississippi River. This stretch of river in low water seasons was treacherous for commercial tow boats and barges, often requiring them to wait up to several days for the river to rise. Lock 27 is the only lock on the Mississippi River System without a man made dam. Tons of rock were laid in the Mississippi to create a small pool elevation upstream from the Chain of Rocks. The drop at Locks 27 can vary from a few feet to over a ten foot drop depending on the river stage.
The Chain of Rocks Lock is operated by the St. Louis District of the U.S. Army Corps of Engineers. Locks #27 are the southernmost locks on the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
and they are the only Locks south of the confluence of the Mississippi River and Missouri River
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
. As such, the Locks move more cargo than any other navigation structure on the Mississippi River.
External links
- U.S. Army Corps of Engineers
- HAER - Upper Mississippi River 9-Foot Channel Project, Locks 27, Granite City, Madison County, IL