Long Slash Branch Watershed

Long Slash Branch

Denham Springs sits entirely within the Amite River Watershed (see page 21). Within watersheds, there are smaller units, known as sub-watersheds, that can experience very different impacts during the same storm events. These impacts are based on the amount of development, the composition of the surrounding environment, and the amount of rainfall. For example, this maps shows how stormwater flows from surrounding areas into Long Slash Branch, which is a sub-watershed tributary through the heart of Denham Springs that carries runoff to the Amite River. High water levels in the Amite River can prevent Long Slash Branch from draining, flooding the area south of Spring Park and downtown Denham Springs.

Soil Composition

Denham Springs sits on a range of soil types, from silt loam to primarily silt soils, each of which has different abilities to absorb and store water. It is important to note that the soils closest to Long Slash Branch have the greatest ability to absorb and store stormwater. LEGEND

Satsuma silt Ouachita, Ochlockonee, and Guyton soils Olivier Silt loam Dexter very fine sandy loam Gilbert silt loam Gilbert-Brimstone sandy loam

Land Development Changes

This map shows where Denham Springs is expanding. Almost all newly developed lands from 2001 to 2016 are located within FEMA’s 100-year floodplain. Further, the development clusters with the highest intensity are concentrated in places with high percent of impervious surfaces and near Interstate 12, both of which are associated with flooding.

LEGEND

Pre-2001 Development 2001-2016 Low Development 2001-2016 Med Development 2001-2016 High Development FEMA Zone AE