Title
Presentation: Update on Little Blue River Flood Risk Mitigation Study
Body
Issue/Request:
Update on Little Blue River Flood Risk Mitigation Study
Key Issues:
• The City partnered with the U.S. Army Corps of Engineers (USACE) and 7 other local agencies to develop a stormwater master plan for the Little Blue River watershed
• This plan focuses on Flood Risk Mitigation (FRM) along the Little Blue River, to include areas such as Oaks Ridge Meadows
• This plan also developed proposals for Ecosystem Restoration to preserve Longview Lake, to include Mouse Creek in southwest Lee’s Summit
• The Tentatively Selected Plan is near completion and approaching public presentations
• Construction would start no earlier than 2029, subject to project(s) funding for which none has been identified at this time.
• Approval of the Tentatively Selected Plan does not incur a financial commitment
Proposed Committee Motion:
No motion for this discussion item.
Background:
The last USACE planning study for the Little Blue River watershed was completed in 1968. That study led to much of the flood control project(s) in the watershed; such as constructing Longview Lake and Dam, Blue Springs Lake and Dam, and levees along portions of the Little Blue River. That study is now obsolete due to the significant changes in land use in the area and more accurate local data relate to topography and rainfall. These changes are evidenced by recurring flooding issues within the watershed of the Little Blue River.
The study estimated $46.6 million of property damage, annually, within the Little Blue River watershed. Inundation mapping especially showed significant impacts to the Oaks Ridge Meadows area of Lee’s Summit. Other areas of Lee's Summit were also impacted. The proposed projects would change the conditions to keep water within the Little Blue Channel during the 1% design storm (commonly called the 100-year event). Work along Mouse Creek would stabilize banks, preserve natural vegetation, and preserve the recreational use of Mouse Creek.
USACE and the local agencies recognize that a best practice to manage stormwater is to manage the entire watershed instead of subdividing into small parcels separated by city limit lines or private parcel boundaries. Rain and flooding follow the watershed, and flooding issues in one community may be inadvertently affected by actions taken outside that community. The watershed is not bound by city limit lines or parcel boundaries.
Discussion among USACE and the local communities regarding this study began in 2021. At that time, the Mid-America Regional Council (MARC) was facilitating initial conversations. The local agencies unanimously agreed to have MARC coordinate the multi-jurisdictional project. USACE has managed the project, provided technical expertise, and conducted the watershed analyses.
The study specifically evaluated projects to reduce damages and risks caused by flooding and ecosystem restoration to stormwater quality and recreational uses. The study is approaching the Tentatively Selected Plan (TSP) milestone. This is the first milestone that requires public engagement of the proposed plans.
USACE will lead two public meetings to offer opportunities for input and identify key issues. City Staff will be working locally to engage key stakeholders ahead of those meetings to ensure there is opportunity for local input. The City may also choose to hold additional public meetings with assistance from USACE staff. The technical aspects will be somewhat straight forward through the hydrology modeling. This will create computer models that simulate potential flooding based on current topography and rainfall data. Predictive modeling can simulate future drainage and flooding patterns based on assumed development.
The City of Lee’s Summit would specifically benefit from this study because two-thirds of Lee’s Summit is within the Little Blue River watershed. Areas included in the study’s scope of work are Prairie Lee Lake, East Fork of the Little Blue River (Vista del Verde ditch), Legacy Park, Mouse Creek, Cedar Creek, the undeveloped PRI Properties, Maybrook Creek, and Oaks Ridge Meadows.
Impact/Analysis:
The purpose of this update is to make Council Members aware of upcoming public meetings regarding this study.
Timeline:
Start: 2022
Finish: 2027
Other Information/Unique Characteristics:
[Enter text here]
Presenter
George Binger III, P.E., CFM
Recommendation
Recommendation: [Enter Recommendation Here]
Committee Recommendation
Committee Recommendation: [Enter Committee Recommendation text Here]