Lake Browning

In 1811 and 1812, a series of massive earthquakes along the New Madrid Fault shook the central united states. According to contemporary accoutns, the quakes caused the ground to "roll in waves," destroyed chimneys in Cincinnati, Ohio, and rang church bells in Charleston, South Carolina.  The quakes also caused part of the Mississippi River and its tributaries to flow upstream, creating Realfoot Lake. 
These 19th Century eathquakes were nothing compared to the seismic activity that rocked the Mississippi River Valley in response to the Big Boom. By the time the ground settled, The Mississippi had widened out into a vast (and radioactive) inland sea from southern Illinois to the Gulf of Mexico. River cities like Memphis--most already flattened by nukes--were submerged. The Mississippi was widened less dramatically farther north, but the force of the water was enough to take down most of the bridges that hadn't already been bombed, leaving only a narrow corridor between St Paul and the Canadian border connecting the eastern and western united states. 
Of course, there's not much reason to cross over the newly formed body of water, which has been dubbed "Lake Browning" for some reason. Between major cities like Chicago and St. Louis, infrastructure targets like TVA plants and a gaseious diffusion plant in western Kentucky, and military targets like Fort Campbell and Scott Air Force Base, the area around the Mississippi marks the western edge of the Nuclear Curtain that separates the Boomlands from densely-nuked Parts Unknown.

Fauna & Flora

There are enough six-legged frogs, man-eating catfish, and atomic-breathed cottonmouths rumored to inhabit the area around Lake Browing to fill a medieval bestiary, but the fallout zones of former river cities, the deadly radiation levels of the lake itself, and the vast wasteland on the other side means that most people have no reason to get close enough to Lake Browning to confirm these stories.

Alternative Name(s)

Lake Mississippi, The New Madrid Sea

Type

Lake