Watershed dams help mitigate flooding

Monday, July 30, 2007
Bourbon County Watershed District No. 102 President Duane Neil examines the emergency spillway at the Cedar Creek dam for possible erosion from recent flooding that swept through Bourbon County. The Cedar Creek Dam is the largest retention dam in Bourbon County. Tribune photo/Rayma Silvers

In 1986, members of the Bourbon County Watershed District No. 102 created a plan to help decrease the negative effects of floodwaters.

This plan paved the way for the building of 60 retention dams over an undetermined time period. Currently, only 14 of these retention dams have been completed and one more dam is currently under construction.

The building of these retention dams has been and will continue to be a long process. Much preparation is required before construction of a dam may begin.

After identifying a potential dam site, watershed district officials must visit with the person who owns the land on which the potential site is located. The landowner must agree to donate his or her easement for the construction of the dam. Next, an engineer must complete geological research, work up a cost analysis, and design the dam according to the state's specifications, Bourbon County Watershed District No. 102 President Duane Neil said.

The most challenging part of the process, the mitigation, is very time-consuming, Neil said. During this process, many different agencies have the opportunity to inspect the land for specific reasons. Some agencies may want to research the number of endangered species living on the land, while others may want to research the plant and tree life. If any of these agencies discover that building the dam will destroy habitats, the watershed district will likely be required to relocate the habitat to a different location. Though necessary, this mitigation process can sometimes create additional costs and more frustration, Neil said.

Funding the retention dam project can be complex, Neil said. Since each dam's size is different, the cost of constructing each dam varies. Construction for each dam costs between $25,000 to $700,000. The total estimated cost to build all 60 dams is $9 million. The cost for building a retention dam is divided three ways. The landowner pays 5 percent of that cost, the watershed district absorbs 15 percent of the fees and the State Conservation Commission funds the remaining 70 percent, Neil said.

Neil said that obtaining the funding to build the dams is a very competitive process. This process makes building the dams increasingly more difficult.

"It's getting harder to build these dams," he said.

Neil said landowners can take preventive measures to help keep flooding from occurring, but those measures will not completely prevent it. One measure is the creation of terraces on the land (a series of ridges designed to slow down the run-off of water).

Since precautions such as creating terraces do not completely alleviate the problem of flooding, retention dams are an important development for further flood protection. The front side of the dam is created using rocks as a top layer, and the back side of the dam has a top layer of seeded grass.These aid in the prevention of erosion. Unlike typical dams which are created to restrain water, retention dams are structured to suppress the water only temporarily to aid in flood prevention. Each retention dam is designed with a pipe inside that allows only a certain amount of water to pass on to the other side of the dam. This slows the dispersment of water down and in turn deters flooding, Neil said.

"I never said the program (Watershed District's retention dam program) would stop flooding. It will help control it," Neil said.

The biggest retention dam created thus far in the Watershed District is the dam at Cedar Creek. The development of the dam at Cedar Creek has three major benefits. The main one is, of course, flood control, Neil said.

The dam at Cedar Creek is the only dam to date that is open to the public. The creation of this dam has also created a nice recreation area for the public to relax and enjoy. At this dam site, boat docks and ramps can be found as well as a public restroom. Many people young and old alike assemble on weekends and in the evenings to enjoy the recreational area.

Cedar Creek dam was also built to provide the rural water district with a supplemental water supply, Neil said.

Neil said the watershed district's retention dam program is the best way for people to protect their farmland against floodwaters.

"Watershed dams are the only effective way to do something about the problem in the district," he said.