Noonday Creek

A large sewer line is buried along most of the creek south (upstream) of the plant, seen as a treeless kudzu-covered flood plain, dotted with concrete mounds topped with manholes.

This is at 34°03′23″N 84°32′08″W / 34.05639°N 84.53556°W / 34.05639; -84.53556 (Noonday Creek, USGS stream gauge NDYG1), 895 feet (273 m) AMSL, and has a watershed area of 24.3 square miles (63 km2).

That is about ten times its normal depth or height, reaching beyond what the Federal Emergency Management Agency (FEMA) and GDNR labeled its 100-year flood plain, largely because of excessive urbanization upstream.

In September 2009, an even worse flood occurred due to a stalled weather system, and the training of heavy showers and thunderstorms over the area.

On September 21, the creek rose even higher than in 2005, blocking not only Georgia 92, but also Interstate 575 at the southern end of the ramps to 92, and flooding the Towne Lake Parkway diamond interchange and underpass (and a gas station) beneath 575 one exit north.

Because of the many closures caused by the creek's inundation, residents of Woodstock and points northward found it took hours to get home, the resulting gridlock extending rush hour well past dusk, with heavy traffic still waiting to get home at 9:00pm on old Georgia 5, which was also blocked north of Woodstock due to the Little River.

The 2009 Atlanta floods were called "of historic proportions" by the local National Weather Service forecast office (NWSFO Peachtree City).

This was after receiving at least 17.5 inches (440 mm) of rain in the past week, half of which fell around midday on September 21, at which point it was already at minor flood stage.

The Hawkins Store Road gauge peaked at just over 17 feet (5.2 m) before it stopped reporting around 4pm, the same time the creek crested at Shallowford.

Noonday Creek Structure number 9, also known as Ellison Lake Dam, is of earthen construction and is used for flood control purposes.