Portable Dredge Combats Water Shortage Along the Rio Grande
On its path from the San Juan foothills in Southern Colorado to the Gulf of Mexico, the Rio Grande River has long lured man to its banks with the promise of nourishing crops and sustaining life with its waters.
Although the river has nurtured many on its course seaward, the Rio Grande has also demonstrated its destructive ways and unwillingness to be tamed by man. Indiscriminately it has flooded the very crops it has helped to grow and the people it once sustained.
For the people of the Middle Rio Grande Valley in New Mexico, the river is one of the major irrigation sources they have. The Middle Rio Grando Conservancy District (MRGCD), the body elected to oversee the valley's water needs, has worked over the years to compensate for nature's shortcomings. It has built diversion dams, reservoirs to store water, and flood controls, as well as improved irrigation and drainage systems. The threat of water shortages, however, continues to be a very real danger for the farmers of the district. However, the farmers of the Middle Rio Grande District are more hopeful now than any time before that they will not have to face any water shortages.
Subhas Shah, district engineer for the MRGCD, explained that water conveyance problems in the middle valley are created by sand and silt carried into the Rio Grande by rivulets and tributaries joining it on its course south. This sand and silt builds up and runs into river reservoirs and dams which feed irrigation canals within the district. The constant accumulation of sediment soon obstructs the flow of water to farmers located downstream and along the ditches that tap into the canal. Further, the silt and sand clog the drainage system and cause unnecessary seepage and evaporation of water or possibly even floods due to rising water levels during heavy rains.
In an attempt to solve this problem, the MRGCD purchased the Mud Cat™, a portable hydraulic dredging system marketed by the Mud Cat™ Division of Ellicott International The Mud Cat™ was placed just south of the Isleta Dam at the settling basin where the Peralta Main Canal first receives water from the Rio Grande. This canal extends approximately 20 miles from Isleta to Tome and provides irrigation water along the way. Throughout the winter the Mud Cat™ moved up and down the canal along a 1500 foot cable, dredging up sand and silt with water at the rate of 2,000 gallons per minute, and depositing it in a disposal site along the canal.
The Mud Cat™ works by cutting up material with its patented cutterhead auger, and then pumping it hydraulically through floating and overland pipes to an approved disposal site.
"This is probably the first time in the history of the canal we've been able to dredge all the silt up and hit the canal's natural gravel bottoms," said Shah. "Now, even though we've had a very dry winter this year we believe that we can furnish irrigation water more efficiently."
The real test of the Mud Cat™'s abilities came in the spring when the canal was opened up for irrigation. Although the Mud Cat™ had been effective during the winter, the Mud Cat™ still had to prove that it could keep up with the heavy silt and sand deposits running into the canal during the normal irrigation season.
The dredge really tackled the job. Due to the excellent performance of the Mud Cat™, they'll be able to keep the canal silt-free year-round. So far the Mud Cat™ has been doing just exactly what they were promised it would. At this rate they're going to have a lot of happy farmers and are considering moving it to another canal where the same problem exists.
This is not the first time the district has dredged the canals. The district had been using another dredge; however, it proved ineffective against the silt and sand deposits and cost the district close to $65,000 in maintenance over a four-year period. Also, it was operational only 30% of the time.
The old dredge was never able to keep up with the flow of sediment into the canal. The result was the build-up of sand bars at the heading of the canal. The result was the build up of sand bars at the heading of the canal, which trapped the water and kept it from the farmers. Many of the farmers lost portions of their crops. Also, the threat of flooding posed real dangers for them. If the Mud Cat™ hadn't been used, the farmers would really be feeling the effects of a water shortage.
Although the Mud Cat™ is very compact it has capacity to handle the unique problems of the canal and is portable so it can be moved to other canals in the district. To transport, it is simply placed on a low-boy truck whereas the old dredge was extremely cumbersome and had to be removed. In addition, the Mud Cat™ requires only an operator and oiler to run.
According to one of the operators, the Mud Cat™ offers tremendous maneuverability and suits its application like a glove and is far easier to handle and much more effective. The old dredge was big and bulky and had to be turned around to go back in the direction it had come from. The Mud Cat™, on the other hand, can dredge going forward or backward.
There are approximately 400 farmers who depend on the Peralta Main Canal to irrigate some 17,000 acres. The growing season in the middle valley extends from May to October. The principal crops grown in the semi-arid, gently sloping lands are alfalfa, corn, cereal crops, fruit and vegetables. There are also many dairy farmers in the district.
There is a great deal of enthusiasm for the Mud Cat™ within the district, and for the improvements the MRGCD has been making in the middle valley since its first inception in the early 1920's.
Like many of the residents of the middle valley, the MRGCD's elected board members also depend on the success of these improvement programs for their livelihoods. Of the seven members who make up the MRGCD's board of directors, three must reside in and represent the Bernalillo County, and one must represent the district at large. The remaining directors reside in and represent each of the other three counties. The MRGCD's board member's job is to service the people's water needs in the district and in purchasing the Mud Cat™ and putting it to work for them they have made their jobs just that much easier.
Reprinted from Land and Water
