Johnson County Stormwater Management Program

Flood Plain Mapping

Overview

The Stormwater Management Program (SMP) contracted for seven watershed studies between 1998 and 2002. These studies are part of a county-wide effort to: 1) identify existing and potential future flooding problems; 2) develop planning level solutions; 3) generate new 1% chance (100 year) floodplain maps based on current conditions and fully urbanized conditions; and 4) develop the data required by the Federal Emergency Management Agency (FEMA) to create updated FEMA regulatory 1% chance floodplain maps. Through this effort, the SMP and the cities have created a tool that will assist in providing a public service to help protect the health, welfare and safety of Johnson County residents and visitors.

Status

The watershed study effort is complete. The technical data and floodplain mapping for each study has been accepted by FEMA. On January 31st, FEMA distributed draft regulatory maps to all Johnson County communities. With the distribution of the draft regulatory maps, the floodplain mapping project has now entered in to the FEMA adoption process. This process takes 12 to 15 months with the following major milestones:

Comment period – typically 30 days for communities to look for major errors and omissions. This period is complete
Legal notice publication – typically 30 to 60 days after the comment period, two legal notices are required to be published one week apart. FEMA is still working on a technical issue at one location – we hope to have this publication occur in the next three to four weeks.
Appeal period – This 90 day period starts on the day of the publication of the second legal notice. This is the period where appeals and protests regarding the “correctness” of the proposed maps are submitted by individuals.
FEMA review – After the 90 day appeal period, FEMA reviews the appeals and protests and makes appropriate changes. If the changes are substantial, FEMA will reissue the maps and start at the appeal period again. The time-frame for FEMA’s review is difficult to estimate.
Letter of Final Determination (LFD) – Once all of the appeals and protests are resolved, FEMA will issue an LFD. The issuance of this letter establishes the effective date for the new maps – this date is six months from the date of the letter.
Adoption period – all communities have six months from the LFD to make necessary changes to their floodplain management ordinance.
Map distribution – Approximately six weeks before the effective date of the maps, FEMA will distribute the maps and associated studies to the communities.

Although this process is ongoing, please note that the results of the watershed studies have been and will continue to be used extensively by cities, the development community, and individual property owners. The cities and development community are using the information as the “best available information” to plan and design new projects while several property owners have been provided the study information as a basis for confirming that their home is not in the 1% chance FEMA regulatory floodplain and that they should not be required to purchase flood insurance.

Impacts of Remapping:

A majority of the status of buildings being in or out of the floodplain has remained the same. However, as a result of this floodplain mapping effort, a number of buildings have either been added to or removed from the floodplain as previously defined by FEMA. The removing and adding buildings to the 1% chance floodplain has occurred for the following two reasons:

The use of updated basemapping which is much more accurate than what FEMA has used in the past.
The 1% chance floodplains defined in the watershed studies extend much further up into the watershed than the current FEMA maps. FEMA regulatory floodplains generally stop at approximately 640 acres of tributary area. The watershed studies define the 1% chance floodplains up to 160 acres. For flood insurance purposes, the FEMA regulatory floodplains will stop at 640 acres while the 1% chance floodplains upstream of this will be considered city/local floodplains and not FEMA regulatory floodplains (i.e. flood insurance will not be required by federal law). The County needs to decide whether and how to administer the 1% chance floodplains upstream of the FEMA regulatory floodplains. Options include local regulations that are either the same as or different than the FEMA regulatory floodplain regulations or just consider these upstream floodplains to be advisory floodplain areas without specific regulations.

Property owners with buildings added to the updated FEMA regulatory floodplain and with a loan from a federally insured lending institution will be required by law to purchase flood insurance. Property owners with buildings that were previously in the FEMA regulatory floodplain and have been removed from the regulatory floodplain based on the new FEMA regulatory mapping will not be required by law to purchase flood insurance although their lenders might still choose to require that the property be covered by flood insurance.

Status of Remapping for Unincorporated Johnson County

We are planning to schedule a public meeting in August to provide information and answer questions for the property owners in Unincorporated Johnson County impacted by the new floodplain mapping. In addition to this meeting, a separate public meeting will be scheduled for the Gardner Lake area because of the number of the properties affected by the new floodplain mapping at the lake.

JOHNSON COUNTY STORMWATER MANAGEMENT PROGRAM
1800 W. 56 Highway
Olathe, KS 66061
Phone: (913) 715-8333
Fax: (913) 715-2453