Our Hydrologic Service Area (HSA)

        There are several major rivers and many smaller tributaries within our Hydrologic Service Area (HSA). The service hydrologist at our office, Mary Lamm, manages the hydrology program. The Paducah HSA closely resembles the  County Warning Area  shown on the office information page, except the boundaries are generally marked by river basins instead of counties. On September 11, 1995, our office assumed a Hydrologic Service Area covering 11 counties in southeast Missouri, 19 counties in southern Illinois, 22 counties in west Kentucky, and 6 counties in southwest Indiana.


       Paducah and its surrounding area is referred to as "the swamp" by many hydrologists in the region. On the contrary, the HSA we cover is highly variable. Crowley's Ridge runs from the Butler/Ripley County area of southeast Missouri northeast across Bollinger County. Steep ridges and valleys contribute heavily to the flash floods so common in this area. The rest of southeast Missouri is relatively flat all the way to the Mississippi River, where there truly is bottomland. Once Crowley's Ridge reaches southern Illinois, it turns east across the state and into southwest Indiana where it becomes rolling hills and sprawling farm land. Only southernmost counties bordering the Ohio River, and those counties bordering the Wabash River, are bottomland. Western parts of west Kentucky begin as bottomland along the Mississippi River then turn to rolling hills around the Land Between The Lakes region.

       Spring flooding varies from year to year, depending on how much snow falls to our north. Snowmelt coming down the Ohio and Mississippi Rivers can cause significant flooding along the bottomlands, even backing up into the many smaller tributaries. Other major flooding is dependent on how much precipitation falls upstream. Paducah's HSA has no headwater forecast points and therefore should  anticipate flood crests rolling down into its area. However, keep in mind a stationary storm or training of storms anywhere in a basin can create flooding. During these situations, gages must be closely monitored.

       Some of the larger rivers we cover are:

  • Ohio River from the Evansville area to the Mississippi River at Cairo
  • Mississippi River from Thebes, IL to New Madrid
  • Green River from Calhoun to the Ohio River
  • Wabash River downstream from Mt. Carmel, IL to the Ohio River
  • Little Wabash River

       We also collect lake level and temperature data for several man-made lakes in the region, including Kentucky Lake and Lake Barkley, Rend Lake, and Lake Wappapello.

        The climate of the mid-Mississippi Valley/Lower Ohio Valley is characterized by warm, often hot and humid summers and cool, sometimes cold, cloudy and frequently damp winters. Snowfall averages around 10 inches per year. Annual precipitation averages between 45 and 50 inches, varying from 2.6 inches in October to 4.96 in March. The average low temperature in January is 24 degrees with an average high of 42. In July, the averages are 69 and 89. The region is particularly prone to the development of severe thunderstorm/tornado activity from late winter through early summer.

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