The Miami Conservancy District’s five dams have protected communities along the Great Miami River and its tributaries for more than a century. But maintaining a flood protection system built in the early 1900s requires more than routine maintenance. It requires continually applying what we learn about the structures, their foundations, and modern dam safety practices.
That was the purpose of MCD’s Dam Safety Initiative, a major, long-term investment in the region’s flood protection system.
Authorized in 1999, the Dam Safety Initiative was created to address three primary needs at MCD’s dams and other flood protection structures: underseepage, permeability near the crests of the dams, and deterioration of concrete. It became the largest capital reinvestment in MCD’s flood protection system since its original construction from 1918 to 1922.
Through 2024, approximately $26.1 million had been invested in dam safety projects through the initiative.
MCD’s dams were designed and constructed using some of the best engineering knowledge available at the time. In fact, many of the original design decisions were remarkably conservative for their era.
But engineering knowledge has advanced significantly since the dams were built.
Decades of monitoring provided MCD engineers with much more information about how water moves through and beneath the dams. New analytical and computer modeling techniques also made it possible to better understand how the structures could respond during extremely large flood events.
MCD’s independent Board of Consultants — experts in dam and levee safety — reviewed data, investigations and proposed solutions throughout the initiative.
That work helped identify improvements needed to address three major areas.
All five MCD dams sit on foundations that contain porous materials such as sand, gravel and boulders. When a dam temporarily stores floodwater, water can move through these materials beneath the structure. This is known as underseepage.
Underseepage itself is expected and can be managed. The concern is making sure water pressure and the movement of water through the foundation remain controlled so they do not affect the stability of the dam.
Over the course of the initiative, MCD installed and improved an extensive system of observation wells, relief wells, toe drains, weighted toe berms and foundation grouting.
More than 500 observation and relief wells are part of the system, including 208 relief wells specifically designed to help control underseepage.
These systems don't eliminate water from the foundation. They safely manage it — and allow MCD engineers to monitor what is happening beneath the dams.
Another concern involved permeability near the crest, or top, of several dams.
During an extreme storage event, water could potentially reach portions of the embankments that were not originally intended to hold water for extended periods. Porous areas near the crest could provide pathways for seepage.
MCD had already completed crest remediation at Germantown Dam in 1970 and Lockington Dam in 1993.
Through the Dam Safety Initiative, impermeable cutoff walls were installed along the entire length of the crests at Englewood, Taylorsville and Huffman dams in 2004, addressing crest permeability at all five dams.
Concrete doesn't last forever.
The concrete surfaces throughout MCD's flood protection system are exposed to water, weather and repeated freeze-thaw cycles. Over decades, those conditions cause deterioration.
The Dam Safety Initiative funded major concrete rehabilitation throughout the system, including work at dams, floodwalls and revetments.
Projects included replacing deteriorated concrete, repairing floodwalls, addressing cracks in dam conduits and completing major rehabilitation at Lockington Dam.
At Germantown Dam, inspections also documented erosion of the concrete floor in the right conduit caused by roughly a century of sand and gravel moving through it at high velocities. That finding led to additional rehabilitation work.
Perhaps the most important lesson from the Dam Safety Initiative is that dam safety doesn't have an end date.
MCD's dams are monitored, inspected and evaluated throughout their service lives. Conditions observed during flood-storage events provide new information. Relief wells must be maintained. Concrete eventually needs rehabilitation. Engineering standards and analytical tools continue to improve.
That is what responsible stewardship of critical infrastructure looks like.
The Dam Safety Initiative represents more than two decades of deliberate investment in a flood protection system that communities throughout the Great Miami River watershed depend on.
The dams may be more than 100 years old, but the work to understand, maintain and strengthen them continues — so they can continue protecting the region for generations to come.
