LaPorte County Streams and Watersheds

Figure 1. Major Watersheds of Indiana.

A watershed is a region of land that drains into a lake, stream, or river. Watersheds are important because everything that is done on the land within a watershed can affect the lake or river into which it drains. The quantity and quality of our water is affected not only by what might be dumped in the river, but by everything we do on the land in the watershed.

Watersheds can be any size. A few acres of land that drains into a pond form a watershed. If that pond drains into a stream, those acres, along with many others, are part of the watershed for the stream. Small watersheds are part of larger watersheds, just as small streams flow into larger streams.

LaPorte County is located within two major watersheds of the United States. The northern third of the county is in the Great Lakes (Lake Michigan) watershed, while the southern two-thirds is in the Mississippi River (Kankakee) watershed. (The dividing line roughly follows the Indiana Toll Road, as shown in Figure 1). Precipitation that falls north of the divide flows north to Lake Michigan, through the other Great Lakes to the St. Lawrence Seaway and eventually to the Atlantic Ocean. Water south of the divide flows generally south to the Kankakee River, which flows west into the Illinois River, then into the Mississippi River and the Gulf of Mexico.

Lake Michigan Watershed
The major portion of the Lake Michigan Watershed in LaPorte County flows to Trail Creek, which empties directly into Lake Michigan. The Little Calumet River, which flows through Porter County to Lake Michigan, drains a small area in the southwest part of the watershed. The northeastern portion of the county drains into the Galena River, which flows north to Michigan, then into Lake Michigan. The landscape in the Lake Michigan watershed is characterized by dunes, including Mt. Baldy, Indiana’s largest migrating sand dune.

Kankakee Watershed
The southern part of the county is drained by many ditches and streams which flow into the Kankakee River. The natural drainage in this area has been altered through the installation of an extensive network of ditches and field tile. The Kankakee River itself was dredged and straightened in the early 1900’s to provide quicker removal of water. This was done to create agricultural land, and has resulted in a great change of the landscape.

Figure 3. Average monthly discharge for LaPorte County streams.

Discharge for a stream or river is the amount of water flowing per unit of time. A typical unit for measuring discharge is cubic feet per second (cfs). Four gauging stations, where discharge is measured continuously in a stream or river, are run by the U.S. Geological Survey in LaPorte County. These four stations are located in Trail Creek at Michigan City, Galena River near Heston, Kingsbury Creek near LaPorte, and the Kankakee River on the St. Joseph County border. The monthly average discharge for two of these streams is shown in Figure 3. Highest flows generally occur in the spring (February-April) while Floodplains are low areas adjacent to river or stream channels and lakes.

Figure 4. Floodplain of LaPorte County.

Floodplains exist because these channels are rarely large enough to contain major floods. These areas have flooded in the past and will flood again in the future. Floodplains have been delineated for parts of LaPorte County by the Federal Emergency Management Agency. A very general map of floodplains is shown in Figure 4. The LaPorte County Health Department has maps that show detailed boundaries of floodplains, which should be viewed before planning any development that may be partly within a floodplain.