Parts of Conroe surrounding the West Fork of the San Jacinto River are in a floodplain. Significant flooding occurs along the floodplain when rainfall exceeds nine inches in a 48-hour period. The Conroe area has approximately a 10 percent chance of receiving this much rainfall in any given year. Urban development in Conroe and the surrounding area has also exacerbated the risk of flooding. Montgomery County experienced three consecutive years of 500-year floods in May 2015, April 2016, and August 2017. A 500-year flood has a 0.2 percent chance of occurring in a year. In addition, a fourth major flood occurred in May 2016, resulting in two major floods in two months. The flooding in August 2017 during Hurricane Harvey dropped nearly 32 inches of rain on the city. To protect the integrity of the dam, San Jacinto River Authority officials released 79,100 cubic feet per second of water from Lake Conroe downstream into the West Fork of the San Jacinto River, exacerbating the flooding already taking place along the floodplain. Conroe city officials ordered a mandatory evacuation of McDade Estates, a neighborhood on the banks of the river. As a response to the flooding, Montgomery County commissioners in October 2017 requested $1.25 million from the federal government for a flood mitigation study, along with an additional $95.5 million to implement various flood mitigation projects.