HURON – As soon as it wins final approval by one more agency, the project to place large boulders in about 100 feet of the James River below the Third Street dam will get under way.
Doing so will create rapids and eliminate the dangerous and deadly undertow.
Local contractor Olson Construction, which in mid-October was awarded a bid of $706,000 for the work, has stockpiled piles of boulders in an area on the east side of the river in anticipation of placing them in the water. That will begin as soon as the Historical Preservation Society gives its stamp of approval to the project, possibly yet this week or next week.
The South Dakota Game, Fish & Parks and the U.S. Fish & Wildlife Service have already reviewed the plan and determined there will be no negative impact to protected or endangered species.
Rocks will be placed starting at the face of the dam and proceeding 105 feet to the south, or just short of the bridge. No boulders will be placed above the dam.
Placement of the boulders will create what’s known as a rock arch rapid or rock ramp on the downstream side of the dam.
According to the city’s website, it’s the most cost-effective and least invasive solution to the dangerous undertow. While leaving the dam in place, it will maintain the water elevation above the dam and minimize the length of disturbance below the dam.
Assistant City Engineer Dennis Bennett said contrary to an artist’s conception of the project that the public viewed earlier, 90 percent of the boulders will be fully submerged under water unless there is low flow in the river.
There has been public concern about young people who would be tempted to go out on the boulders sticking up out of the water.
It has long been a goal in the city of eliminating the drowning risk and dangerous recirculating currents at the downstream side of the dam, known by experts as “the drowning machine.”
Eliminating the danger posed by the low-head dam was a big priority when the public gathered for input meetings that led to the unveiling of the comprehensive James River Recreation Area Master Plan in 2013. The plan also includes proposals from Stockwell Engineers of Sioux Falls pertaining to Ravine Lake and other areas up and down the James River.
Other work included in the Olson contract with the city includes landscaping, dirt work, clean up and concrete walkways and stairways.
The $706,000 bid awarded this fall was considerably below the original $850,000 project estimate. The James River Water Development District also contributed $150,000.
Mayor Paul Aylward said the City Commission has been setting aside funding for the past several years to the project.
The Third Street dam was built in 1936 as a conservation project during the “Dirty 30s.” The work created a small reservoir for the city’s water supply.
Huron now draws its drinking water needs from ground wells and from the Mid-Dakota Rural Water System.