The Miami Conservancy District (MCD) flood protection system is ingeniously simple. The drainage patterns of the entire Great Miami River Watershed are incorporated into its design. The dams and levees operate without human intervention and have no moving parts, except floodgates on storm sewers along the levees.

MCD's flood-protection system was the first of its kind. It was designed to use five dry dams, meaning the dams are used only to hold back floodwaters after heavy rainfall. The remainder of the time, the land behind the dams – 35,650 acres – is used predominantly for parkland and farmland.

The levees and modified river channels in the 11 cities along the river work with the dams as part of the flood protection system. The levees and channels are designed to carry the flows released by the dams, keeping floodwaters out of the cities.

The MCD flood protection system also utilizes floodplains along the rivers, allowing room for the floodwater flow. Many floodplain areas are preserved so development does no encroach into the floodplain, causing the water to flow faster or deeper.

• The MCD flood protection system includes five dams: Germantown, Englewood, Lockington, Taylorsville and Huffman.
• The MCD flood protection system includes levees and channel modifications in Piqua, Troy, Tipp City, Huber Heights, Dayton, West Carrollton, Moraine, Miamisburg, Franklin, Middletown and Hamilton.
• The dams, levees and channel modifications were constructed simultaneously between 1918 and 1922.
• The dams operate without human intervention and have no moving parts.
• Water is controlled through conduits at the dams that allow only the amount of water the channel can handle downstream. The remaining floodwaters are stored behind the dam in temporary pools.
• Floodgates on storm sewer outfalls along the levees do require manual operation. The floodgates are closed during high-water events to prevent the river's rising waters from backing up into the storm sewers and flooding the protected areas behind the levee.
• It cost $30.36 million to construct the original system. Careful attention to planning, financing, legislation and implementation resulted in the most comprehensive flood protection system in the nation. 
• To replace the system today, it would cost more than $912 million, based on the Engineering News Record Construction Cost Index.
• MCD employees maintain the five dams, 55 miles of levee and 35 miles of stream channel. 
  • The maintenance program includes controlling growth of vegetation, repairing scours, removing deposits in the channels, operating more than 200 floodgates, and removing drift and debris following high water.