Shawnee County is part of the Kansas-Lower Republican Basin that includes all or part of 25 counties in the northeast corner of Kansas. The Kansas-Lower Republican basin covers nearly 10,500 square miles of northeast Kansas and includes that portion of the state drained by the Republican River downstream of Harlan County Dam in Nebraska and the Kansas River which originates at the junction of the Republican and Smoky Hill rivers.

Within this basin, Shawnee County is further divided between two sub-basins: the Middle Kansas Watershed (HUC 10270102) and the Lower Kansas Watershed (HUC 10270104).

Middle Kansas Watershed. The Middle Kansas Watershed comprises the northern two-thirds of Shawnee County and drains to the Kansas River. Major creeks in this watershed include: Bourbonais Creek, Cross Creek, Walnut Creek, Soldier Creek, Little Soldier Creek, Half Day Creek, Indian Creek, Muddy Creek, Little Muddy Creek, Elm Creek, Indian Creek, Post Creek, Vassar Creek, Mission Creek, Blacksmith Creek, Shunganunga Creek, Colly Creek, Deer Creek, Stinson Creek, Tecumseh Creek, Whetstone Creek, and, the Kansas River.

Lower Kansas Watershed. The Lower Kansas Watershed comprises the southern third of Shawnee County and drains to the Wakarusa River. Major creeks in this watershed include: Six Mile Creek, Burys Creek, Lynn Creek, Deer Creek, Camp Creek, and the Wakarusa River.

Each of the major creeks and associated tributaries within Shawnee County have an associated floodplain. Although each creek is different in its physical characteristics, all experience flooding conditions caused primarily from excess flow following major rain events.

In Shawnee County, the Special Flood Hazard Area (SFHA) cover approximately 55,584 acres (86.9 square miles) or approximately 16% of the county. The Shawnee County Flood Data Viewer can be used to gain quick access to current flood zone data.

Shawnee County Flood History. There are no natural obstructions to flood flows in the floodplains. Obstructions have been built by man's continued encroachment on to the floodplains. In the study area, bridges, landfills, and levees are the most prominent manmade obstacles. As an indication of past flooding, the following composite accounts describe some of these events.

Flood of June 1844 ‐ "It commenced raining . . . (and) rained all day without a moment's cessation," wrote Oregon-bound James Clyman on June 10, 1844, "Knife River (Cross Creek) . . . rose 15 feet during the day." Thus grew perhaps the greatest and certainly the most legendary of the Kansas River floods. For several days the rain continued, though briefly, the sun shone on the 13th. Then "we saw the sun and a general shout was raised through all the camp after 80-hours steady rain we saw the Kansas River from the bluffs and it shews 8 or 10 miles wide." Outside the City of Topeka the flood waters inundated the other valley cities of Rossville, Silver Lake and Tecumseh. At least two men from the City of Rossville, living on a river island south of town, drowned, but most if not all of the City of Silver Lake people got out in time and the water was never exceptionally high in either place.

Flood of May 1903 ‐ May 1903 began quite bright as Topekan’s planned for President Theodore Roosevelt's imminent visit. It ended with enormous destruction and misery. Heavy rains began in mid-month and then on Memorial Day the Kansas River broke out of its banks quickly spreading throughout the low-lying North Topeka residential districts. In a matter of hours water covered North Topeka, the fertile Shawnee County bottoms, and sections of South Topeka and Oakland from five to 25 feet deep. "Secured places became perilous," noted author Margaret Hill McCarter ("The Overflowing Waters") in her account of the flood, "lapping inches of quiet water became swiftest currents on which a few lives must have ridden to unrecorded deaths; not a few bodies must have floated to unknown burial."

Flood of June 1943 ‐ Heavy rains over the Kansas River basin during the period of June 5- 6, 1943 caused damaging floods along the Kansas River from Junction City to the mouth. This flood had two distinct overflows in the City of Topeka with the higher being during June 16-18. This flood has been exceeded nine times.

Flood of April 1945 ‐ The greatest flood recorded on Shunganunga Creek occurred in April 1945 during a time when the Kansas River was at a high stage. Flooding on the larger stream overshadowed the flooding on the creek, and for this reason the Shunganunga Creek flood was not adequately documented, although considerable damage occurred.

Flood of July 1951 ‐ Heavy rainfall in the Kansas River basin began in early May, continued through June and ended in the critical storm of July 9-13, 1951. Precipitation during this storm, which fell on saturated soil, amounted to as much as 18.5 inches and averaged eight inches over the eastern half of the basin. The runoff during May, June and July was three times the average annual discharge. The flood crested on July 13, 1951 and is the largest of record with a discharge of 469,000 cubic feet per second (cfs).

The flood of June 1951 began on June 26, when the City of Topeka received 2.7 inches of rain which caused Shunganunga Creek to flood nine square blocks southwest of the fairgrounds. Thirty-five to forty homes and the grocery stores were affected. East of Winter General Hospital, 175 homes and one apartment building were affected. Overflows also occurred in other areas causing damage to commercial and industrial facilities During July of 1993, similar conditions mimicking the 1951 flooding season lead the Kansas River, near the City of Topeka, to crest nearly 9 feet above normal flood stage. However improved controls such as levees and water control reservoirs withstood higher water levels and limited severity as planned. Despite some local concern and uncertainty, The City of Topeka was left relatively unscathed with minor damages occurring form some negligible levee issues.

Shawnee County continues to experience major flood events for which flood awareness and proper floodplain management is a continuing necessity.

Source: Flood Insurance Study, Shawnee County, Kansas, Vol. 1 of 2, Effective Date of September 29, 2011

Where to Obtain Flood Information. Information on whether your property is in a high-risk area can be obtained by contacting the Shawnee County Planning Department at 785-251-5410, stopping by our office at 1515 NW Saline Street in Topeka. We have maps that are available as well as other flood related information. By contacting the Planning Department, Shawnee County can offer you assistance with elevation certificates for new developments and help alleviate confusion over regulations for floodplain development.