Aging dams need attention

Resource, Oct 1999 by Reed, Pearlie S

Public safety is at stake if action is not taken

In my nearly 30-year career in USDA, I have never been as concerned about a public safety issue as I am with the growing problems of aging upstream flood control dams.

Local communities, with assistance from the Natural Resources Conservation Service (NRCS), have constructed more than 10,000 upstream flood control dams since 1948. Many of these small dams are at, or soon will reach, the end of their design life. Many have significant rehabilitation needs. Some pose a threat to public safety to those downstream or who use their reservoirs as a drinking water source. Other dams could create adverse environmental impacts in the same downstream floodplain they have been protecting.

Along with my concern about the dams, I'm also tremendously proud of the USDA's small watershed program. Projects owned and operated by local sponsors are providing flood control, municipal and irrigation water supply, recreation, erosion control and wildlife habitat enhancement on more than 130 million acres (52 million hectares) in the nation. We estimate that the small watershed program yields more than $800 million in annual benefits.

Projects that reduce flooding to prime farmlands, highways, residences and businesses have become an integral part of communities in every state in the nation. They provide a $14 billion national infrastructure and impact thousands of people's lives each day. These structures would be an appropriate topic for ASAE's "Greatest Agricultural Engineering Achievements of the Century."

However, many of these project areas are in a far different environment than when originally constructed. Population has grown, development has occurred up and downstream from the dams, land use changes have taken place, sediment pools have filled and structural components have deteriorated. Many do not meet state dam safety regulations enacted and revised with more stringent requirements since the dams were built.

Many dams lie in upstream agricultural areas unknown to most residents protected by them. Many are quietly deteriorating as time takes its toll on their components. Unless something is done to rehabilitate them, they will not age gracefully, and if the dams should fail, they won't be a secret any more.

A recent survey of known rehabilitation needs in 22 states found that more than 2,200 dams need rehabilitation at an estimated cost of more than $540 million. As time passes, deterioration and construction costs will increase.

Besides human health and safety issues, rehabilitation would also provide opportunities for communities to capitalize on potential new benefits such as adding municipal and irrigation water supplies, recreation, and wetland and wildlife enhancements. Rehabilitation would meet current state and federal environmental and safety standards. In some cases, where flood control can be achieved by other measures, dams may even be removed and the sites restored to natural conditions as much as possible.

Today, technology advances, design and construction experience, and updated design criteria have improved dam safety. Design methods are more sophisticated than when many of the dams were designed and built.

Emerging technologies can also be applied to help make older dams safer. Robotic cameras can inspect pipes, sediment volume in reservoirs can be determined using seismic investigation, sediment pollutants can be measured through chemical testing and improved flood warning systems can be installed.

Agricultural engineers have an important role to play in developing technology and applying existing technologies to rehabilitate aging dams. ASAE can be a vehicle to bring practicing engineers and scientists together to interact and exchange information. This participation will help spawn research and provide confidence for practicing engineers and scientists.

I would encourage ASAE SW-25 Committee Water Resource Structures to pursue this area. If you have questions concerning rehabilitation of dams in your area or have suggestions on how emerging technologies can be applied to rehabilitation, I encourage you to contact your local soil conservation district or ASAE member Larry Caldwell, NRCS's state conservation engineer in Oklahoma. He is providing national leadership in raising awareness of this critical public safety issue and can be reached at 100 USDA, Suite 206, Stillwater, OK 740742655, USA; 405-742-1254, Larry.Caldwell@ok.usda.gov.

Reinvesting in America's watersheds is a big challenge and we need to work together to find a solution - raising awareness, encouraging debate, finding funding and developing new partnerships to protect this investment.

Pearlie S. Reed is chief of the Natural Resources Conservation Service, U.S. Department of Agriculture, P.O. Box 2890, Washington, D.C., 20013-2890, USA; 202-720-7246, fax 202-720-7690.