Clearing debris and silt means a better supply of water.

The lengthy drought in Montana prompted two neighboring conservation districts in the Big Sky State to forge an innovative partnership. The Missouri and Yellowstone rivers deposit silt and debris throughout the year, and even when there is normal water flow, irrigators need to clear away that debris so they can use their pumps. The situation is even worse in years of drought or low water level. Sometimes irrigators have to trench from their pump sites to the river just to access the needed water. Traditionally, this has been done with equipment like draglines and trackhoes (and even dynamite), and it has become more expensive and problematic each year. The excavated debris and silt were piled on the riverbanks, in mounds that seemed to encourage noxious weeds. The mounds created could even change the flow patterns of the rivers to create more silt problems.

SRS Crisafulli customized this 20-foot dredge, its smallest ever, especially for work on the Missouri River.

The dredge can perform in just 14 inches of water.

Two years ago, the Richland and Roosevelt county conservation districts invested in a new method to clear the way for irrigators. The two conservation districts acquired a dredge from a Montana manufacturer, SRS Crisafulli in Glendive. (The company has sold its dredges all over the world, not just in Montana!) This decision has allowed irrigators with property along the Missouri River from Fort Peck to the border of North Dakota, as well as irrigators who work by stretches of the Yellowstone River that flow through Richland County, to use a modern, environmentally friendly method to access the water.

“This dredge was built especially for work on the Missouri River,” observes Eric Lillberg, senior applications engineer at Crisafulli. “Much of the equipment we make is customized to suit specific projects, and this was typical of that commitment to customers. This 20-foot dredge is the smallest man-powered dredge we’ve built, because that’s what the site conditions demanded. It can work in 14 inches of water. Many of the dredges we have built are used on lagoons, but this one had to be maneuverable on a river. The design took us about three months. After its initial work on the river, we noticed a way in which the equipment would work even better and changed the cutterhead to improve performance.” The self-propelled dredge could be described simply as a pontoon that floats and carries a powerful pump, but there is clearly much more to the engineering requirements than that. It must comprise components that are of a weight that is stable but buoyant enough to float in water that is not always deep, it must travel from site to site, and it must be maneuverable.

How big a problem could this become, this silting of access points for the irrigators? There are more than 150 pump sites on the Missouri River from Glasgow, MT, to the Montana–North Dakota border and almost 20 sites along the stretch of the Yellowstone in Richland County. In years of normal precipitation, these sites must be cleaned to be of any use to irrigators, and the problem is worse in times of lower water flow (which could be due to less rain or less snow through the winter months to produce a good runoff). Local, state, and federal agencies were all interested in the solution considered and proposed by the Richland and Roosevelt conservation districts, because this problem of reaching available water from rivers is not confined to eastern Montana. There are many regions in North America where the problem is similar and could be solved in a similar way. Silt and debris are natural problems for most rivers and streams; their efficient removal makes pumping good water so much easier for irrigators.

Of importance equal to the efficiency of the Crisafulli dredge may be the cooperation between soil conservation districts that this project has demonstrated. “This dredge project is a good example of what conservation districts can do when they work together,” comments Vicki Marquis, watershed coordinator for the Missouri River Conservation District Council. “It took federal, state, and local entities working together to pull this off.” Irrigators can hire the services of the dredge from Richland County Conservation District or Roosevelt County Conservation District. Officials at the districts emphasize that irrigators must get permits before dredging, but information on permitting procedures is readily available from the districts.

The small, maneuverable dredge on the Missouri River and Yellowstone River can clean about 70 cubic yards per hour, and it disposes on the dredged silt and debris in a way that does not build large, potentially hazardous mounds on the immediate riverbank. Initially the dredge was operated by Keenan Engelke of Culbertson, MT, under a contract with the conservation districts. We wondered if it would be possible for a local authority’s own people to run the dredge. “Many customers, such as municipalities, counties, and industrial entities, have their own people who can run a small dredge,” advises Mike Mills, director of engineering and manufacturing at SRS Crisafulli. “Most customers do not hire outside contractors to run the equipment. On river projects, knowing the river and its idiosyncrasies would be a major starting advantage, but counties and conservation districts may have such people available as temporary operators. It’s not difficult to run the dredge. It takes time to develop a technique and pattern of work, but we have hundreds of people worldwide who are running them successfully without having any specific prequalifications in dredge operation.”

The potential is exciting. With more periods of drought forecast for many parts of the country, it seems that the ability to get water from available sources is of paramount importance. What frequently prevents those involved in agriculture’s multifaceted sectors from getting the water they need is often the situation in the water—the silt and the debris. The example set by the two conservation districts in Montana could be the light at the end of the tunnel—or the water at the end of the gully—for many others in similar dry situations this year.

EC - January/February 2008