Building a Slack-Water System on the Upper Mississippi
At the time of the 9-Foot Channel Project authorization, slack-water navigation systems were not new. But, with the Upper Mississippi River 9-Foot Channel Project, the Corps of Engineers created a slack-water system that used non-navigable dams. And, as with so many other elements of the 9-Foot Channel Project, the decision to use non-navigable dams on one of the nation's most important waterways was controversial.
As its name implies, a slack-water navigation system is comprised of a series of "still water" pools, created by a series of dams across the river. The pools are connected by navigation locks. French and American engineers had begun building slack-water navigation systems in rivers in the 1830s. U.S. Army engineers began studying such river improvements in the 1840s. The Corps of Engineers' first bank-to-bank structure was the Davis Island Lock and Dam on the Ohio River. The Corps designed the Davis Island Lock and Dam between 1874 and 1878. When it was completed in 1885, the Davis Island Lock and Dam initiated what became, until the Upper Mississippi River 9-Foot Channel Project, traditional American practice for slack-water navigation.
Corps engineers designed the Davis Island Dam as a masonry sill set into the riverbed. Superimposed on the sill were Chanoine "wickets" or gates. When the water level on the Ohio River was low, river traffic had to pass through a lock to get across the Davis Island Dam. However, during the relatively long high-water stages on the Ohio River, some of the dam's wickets were laid flat across the sill, permitting river traffic to pass directly over the dam. Because the wicket gates of the Davis Island Dam could be moved, the dam was considered "movable." Because river traffic could pass over the Davis Island Dam rather than having to go through the lock, the dam was "navigable." In a non-navigable dam, all river traffic must pass through the lock, regardless of how high the river's flow.
A movable dam was the key to successful slack-water navigation. Although movable dams have existed in primitive forms since ancient times, the modern movable dam is usually traced to a series of improvements that began in 1832 when Thenard, an officer in the French Corps of Engineers, devised a system for raising panels in a dam through the use of chains attached to a winch. Early American movable dams drew on native innovations, such as the bear trap dam gate invented by Josiah White in 1818 for use on the Lehigh River. However, because they did not include locks, these early experiments with movable dams did not produce slack-water navigation systems as they are defined today. Traffic either passed directly over the dams or through gates in the dams. American slack-water navigation systems that included locks as well as dams were located on Ohio's Muskingum River as early as 1832, and on Kentucky's Green River in 1833. 
Rivermen and engineers preferred navigable dams for a variety of reasons. Foremost among them were the types of vessels that navigated America's rivers, On both the Ohio and Upper Mississippi Rivers, barges were a major form of transportation. Developed by western rivermen after the Civil War, the barge system was seen as a high volume method of competing with the railroads. After 1866, coal shippers used the barge system extensively in the Ohio River Valley and its tributary region. The lead mining companies of the Upper Mississippi River Valley also used the barge system, and it was not long before grain haulers began using barges to haul bulk agricultural products out of the region. Fleets of 8 to 20 barges, bound to a steam towboat by a complex system of cables and chains, were a common sight on the Upper Mississippi after 1870. 
The Upper Midwestern lumber industry also depended on open river navigation. From 1870 until about 1905, logs were a major commodity transported on the Upper Mississippi River. The lumber companies floated many of the logs harvested in the forests of Wisconsin and Minnesota down the Upper Mississippi to markets and saw mills as far south as St. Louis. Between 1875 and 1900, more than 100 special steamboatscalled raftboats because they pushed massive log rafts downrivertraveled the Upper Mississippi. While a typical steamboat rarely exceeded 100 by 300 feet, a raftboat and its log tow often measured 300 feet wide and 1,500 feet long. Raftboats and their tows needed a wide, open river. Because the tows would have had to be broken up and reassembled repeatedly, neither barge/towboat units nor raftboats could be operated economically in a lock-bound, non-navigable dam system. 
Packet boat operators were also opposed to non-navigable dams, Packet boats carried passengers, mail, and valuable or special freight. Competing with the railroads, packet boats operated on tight schedules. On the Upper Mississippi River, it would have taken approximately 40 hours for a fleet of barges to pass through a lockage, while a packet boat needed only an hour or less. Still, in their stiff competition with the railroads, that hour was just as critical for the packets as the 40 hours were to the barges.
Prior to the 9-Foot Channel Project, virtually all of the navigation improvements on the Upper Mississippi provided for open river navigation. In 1882, the Corps began building a series of dams on the headwaters to help improve the navigability of the Upper Mississippi. These dams created pools whose waters were released to supplement the natural flow of the river south of Minneapolis during periods of low water, Because the dams were not located in navigable reaches of the river, they were in accord with the idea of keeping the navigational areas of the river as free from obstructions as possible. 
The Corps' commitment to open water navigation was also acknowledged in 1894 when the Corps began building the first two locks and dams spanning the Upper Mississippi. These two locks and dams did not impair open water navigation anywhere that such navigation was already being practiced. Both of these structures were between St. Paul and Minneapolis, that is, at the head of navigation. Thus, they impaired very little traffic and, in fact, opened a whole new stretch of the river to any kind of substantial navigation for the first time. 
In 1903, Montgomery Meigs, a civilian employee with the Corps' Rock Island District, broke with this pattern of building only navigable structures on the Mississippi River. Meigs, whose father had assisted Robert E. Lee in the 1837 study of the Upper Mississippi River, endorsed a plan to build a bank-to-bank structure at the foot of the Des Moines Rapids. Conceived by the Keokuk and Hamilton Water Power Company, this plan called for the construction of a non-navigable dam in the very heart of the navigable section of the river. 
The Keokuk and Hamilton Water Power Project was the result of an idea that had been germinating since at least 1836: exploiting the water power available at the foot of the Des Moines Rapids. By the 1880s, the concept of multipurpose water resource development had gathered support throughout the country. Leaders of the emerging progressive and conservation movements had fostered an awareness that America's waterways should be developed not only to aid navigation, but also to control floods, irrigate crops, generate hydroelectric power, and provide water for municipal and industrial use. Simultaneously, navigation faced a crisis. The 1890s marked the victory of rail over water-borne transportation for long-distance hauls. In ever increasing numbers, water transport boosters jumped on the multiple-use bandwagon. 
In 1900, a group of about 25 residents from the towns of Keokuk, Iowa, and Hamilton, Illinoistwo Mississippi River towns located directly across from each otherincorporated themselves as the Keokuk and Hamilton Water Power Company with the express purpose of developing hydroelectric power. In 1901, the Federal Government gave permission to the company to build a wing dam on the Illinois side of the river. The Keokuk and Hamilton Water Power Company hired Lyman R. Cooley, a hydraulic engineer from Chicago, to develop specifications for the project. Cooley concluded that a wing dam was impractical, and that it would take a dam all the way across the river to effectively generate enough hydroelectric power to be a commercial success. Because the installation Cooley suggested included a navigation lock, it would also solve the long-standing navigation problems associated with the Des Moines Rapids. 
In June 1902, Congress asked the Corps of Engineers to determine if the Keokuk and Hamilton Water Power Company project would benefit or impede navigation on the Upper Mississippi River. Charged with this task, Montgomery Meigs concluded that the non-navigable dam at Keokuk would benefit river transportation, while allowing effective use of the river for hydroelectric power generation. Meigs acknowledged that 15 percent of the downstream river traffic went directly over the Des Moines Rapids, rather than passing through the existing by-pass canal and locks. But he also noted that the percentage of traffic using open river navigation was declining rapidly. Meigs predicted it would continue to do so as the Upper Midwest lumber industry declined, and the lumber marketing and processing facilities upstream from Keokuk came to increasingly dominate what was left of the business. By 1902, there was only one sawmill left below Keokuk.
Meigs also endorsed the plan because of new advances within the shipping industry. Developments in barge and towboat technology had made it possible to haul ore and grain in less cumbersome fleets. Moreover, long-distance packet boat operators had lost their battle with the railroads. By 1903, packet boats were no longer a significant user group on the Upper Mississippi River. As a result, Meigs advised Congress that the Keokuk installation, which included a non-navigable dam with one lock, would save time for the vast majority of river traffic. He also estimated that, had the facility existed between 1890 and 1901, river users would have saved 12,000 hours, which would have reduced shipping costs 0.6 cent per ton of freight. 
In February 1905, Congress gave permission to the Keokuk and Hamilton Water Power Company to build its dam and powerplant. By allowing this project, Congress and the Corps cleared the way for the later 9-Foot Channel Project. The Keokuk project, completed in 1914, established the precedent for non-navigable dams on the Upper Mississippi. It also showed that the free flow of the river could be interrupted in mid-stream without unacceptable damage to the river, surrounding lands, or economics. 
Despite the Keokuk project authorization, the Corps did not immediately begin building non-navigable dams elsewhere on the Upper Mississippi. In fact, the next major structure the Corps built on the Upper Mississippithe Moline Lock, completed in 1908 and located 123 river miles upstream from Keokukwas specifically designed for open water navigation. Similarly, in 1913, when the Corps developed plans for a lateral canal and lift lock to allow circumnavigation of the Le Claire section of the Rock Island Rapids, it continued to ensure open river navigation. Congress authorized construction of the Le Claire Canal in March 1914. However, the outbreak of war in Europe dashed any hopes for a quick startup. When, by the summer of 1920, construction had still not begun, the Corps took this opportunity to re-examine its designs for the canal and lock in light of recent developments in waterway technology. Interestingly, the Corps continued its commitment to open water navigation. The 1921-1924 construction of the Le Claire Canal and its appurtenant structures in no way hampered open water navigation. 
The Corps remained committed to open water navigation on the Upper Mississippi in 1925 when plans were made for a lock and dam complex at Hastings, Minnesota. However, this structure, built between 1928 and 1930, did not leave as much room for open water maneuvering as the Moline and Le Claire installations, The Hastings complex (now known as Lock and Dam No. 2) only included a 100-foot-wide navigable pass adjacent to the lock. It also included 20 Tainter gates. In narrowing the space reserved for open river navigation and utilizing Tainter gates for the first time on the Upper Mississippi River, the Hastings Lock and Dam acted "as a sort of engineering link" between the Corps' 6-foot channel structures and philosophy and its mature 9-foot channel structures and philosophy. 
In its final survey report of the 9-Foot Channel Project, the Corps' special Board of Engineers noted that it had considered three methods of securing a 9-foot depth on the Upper Mississippi: (1) regulation and dredging; (2) a combination of reservoirs, regulation works, and dredging; and (3) canalization by locks and dams. The first system, regulation and dredging, was the primary method used to obtain the 6-foot channel. Although the survey report acknowledged that "modern self-propelled dredges" could supplement regulation works, it also noted that regulating the flow of the river through contraction works such as wing and closing dams would be impractical on many stretches of the river. The survey team also studied the feasibility of a storage reservoir system on the Upper Mississippi River. Although at least 34 possible reservoir sites were identified, the Corps concluded that even if that many reservoirs were operated as a unit, they would still not ensure a dependable 9-foot channel depth, even if supplemented by regulation and dredging during dry years. 
Just as Major Hall had concluded in his initial survey of the Upper Mississippi River project, the special Board of Engineers determined that a slack-water navigation system was the most feasible method of obtaining a 9-foot depth. By early 1930, Corps engineers had also begun to reconsider their commitment to open water navigation on the Upper Mississippi. In March of that year, Minnesota Representative William I. Nolan proposed legislation that would give the Corps the right to make changes in the type and location of the 9-Foot Channel Project dams. Clearly, the Corps was beginning to consider the use of non-navigable dams. 
1. Leland R. Johnson, The Davis Island Lock and Dam 1870-1922 (Pittsburgh: U.S. Army Corps of Engineers, Pittsburgh District, 1985) 8-9, 13, 16, 25-26, 34-36; Johnson, The Falls City Engineers: A History of the Louisville District Corps of Engineers. United States Army (Louisville: U.S. Army Corps of Engineers, Louisville District, 1974), 98-99, 142-143, 147-148; and Louis Hunter, Steamboats on the Western Rivers, An Economic and Technological History (Cambridge: Harvard University Press, 1949), 206-212.
3. For general information on log and raftboat movement on the Upper Mississippi see Tweet, Rock Island District, 238-243; William J. Peterson, "Rafting on the Mississippi: Prologue to Prosperity," Iowa Journal of History 58, No. 4 (1960): 289-320; Robert F. Fries, Empire in Pine: The Story of the Lumbering Industry in Wisconsin, 1830-1900 (Madison: State Historical Society of Wisconsin, 1951), 8-59; Agnes M. Larson, History of the White Pine Industry in Minnesota (Minneapolis: University of Minnesota Press, 1949), 3-70; and Charles E. Twinning, Downriver, Orrin H. Ingram and the Empire Lumber Company (Madison: State Historical Society of Wisconsin, 1975) passim.
6. Completed in 1903, Montgomery Meigs's report was published in 1916. See "Report of Mr. Montgomery Meigs, U.S. Civil Engineer," Annual Report, 1916, Vol. II (hereafter referred to as Meigs Report), 1509. (Beginning in 1867, the Federal Government started printing and binding the Annual Report to the Chief of Engineers. Published at the end of the fiscal year, the exact title and format of the series has varied slightly from time to time. Hereafter all reports from this series will be referred to as Annual Report, followed by the fiscal year which the report covers.) For a more complete biography of Meigs, see Tweet, Rock Island District, 357-358.
7. Samuel P. Hays, Conservation and the Gospel of Efficiency: The Progressive Conservation Movement 1890-1920 (Cambridge: Harvard University Press, 1959, reprinted with a new preface by the author, New York: Antheneum, 1974), 93-94, passim; Johnson, Louisville District, 170; George Whaton James, Reclaiming the Arid West: The Story of the United States Reclamation Service (New York: Dodd, Mead, and Company, 1917); The U.S. Reclamation Service: Its History, Activities and Organization (New York: D. Appleton and Co., 1919); and Alan R. Dickerman, George E. Radosevich, and Kennet Noble, "Foundation of Federal Reclamation Policies: An Historical Review of Changing Goals and Objectives" (Ft. Collins: Department of Economics, Colorado State University, 1970).
8. Nelson C. Roberts and S. W. Moorhead, Story of Lee County, Iowa (Chicago: The S.J. Clarke Publishing Company, 1914), 243-254; Tweet, Rock Island District, 245; and Rivers and Harbors Act of June 13, 1902.
11. Johnson, Davis Island Lock and Dam, 37-41, 133; Michael C. Robinson, History of Navigation in the Ohio River Basin: National Waterways Study: U.S. Army Corps of Engineers Water Resources Support Center. Institute for Water ResourcesNavigation History NWS-83-5 (Washington D.C.: Government Printing Office, 1983); Clarence Newman, Ohio River Navigation: Past. Present. Future (Cincinnati: U.S. Army Corps of Engineers, Ohio River Division, 1979), 23-24; Tweet, Rock Island District, 103; and L.E. Wood, "A Nine Foot Depth Below St. Anthony Falls! ", Old Man River 5, No. 5 (n.d.) 2-8, Old Man River Safety Bulletins 1938-1940, Box 2, Entry 1626, National Archives, Kansas City Branch (hereafter referred to as NAKCB).
12. Roberts, "Kanawha River," 337-338; Daley, "Canalization of Upper Mississippi," 105; McAlpine, "Roller Gates in Navigation Dams," 419; Gross and McCormick, "Upper Mississippi River Project," 313-314; and Malcolm Elliot, "The Upper Mississippi River Project with a Discussion of the Movable Gates in the Dams," paper presented at the Western Society of Engineers, Chicago, November 1, 1937, 4-5, in RG77, subgroup: St. Paul District, General Records 1934-1943, Box 40, Entry 1629, File 4013.1/113, NAKCB. Hydraulic jump is a phenomenon associated with the tendency for water flowing over a structure to fall in a determinable curve. If the curve of the water falls well beyond the face of the structure a vacuum can form that literally sucks the concrete or other building material from the structure. Careful design and the provision of baffles and settling basins serve to reduce and control hydraulic jump. Scour is a condition that results from water passing over a structure and rolling along the riverbed below the structure. The force of the water can excavate large holes in the riverbed, ultimately undermining the structure. The downstream apron, derrick stone protection, and baffles reduce the force of the water.
17. Ibid.; S.G. Roberts, "Roller-Gate Dams for the Kanawha River," Engineering News Record 111, No. 21 (September 21, 1933), 338, 340; and George R. Spalding to Chief of Engineers, February 9, 1930, RG77, District Files, 1923-1942, Box 825, File 2294, NA.
Last Updated: 01-Feb-2008