East Lansing Wet Weather Resiliency Plan Virtual Open House

About the Project

In recent years the City of East Lansing (City) has been impacted by extreme storm events that have resulted in flooding throughout many neighborhoods. Climate science performed specifically for the East Lansing region indicates that these extreme rain events will likely become more frequent and more powerful as we move into the coming decades. In response to this growing risk, the City has initiated the development of a Wet Weather Resiliency Plan. The purpose of the plan will be to provide a future roadmap for reducing flood risk and creating a safer, more flood resilient city for its residents, businesses, and visitors. The plan is being developed with financial support from State of Michigan Department of Environment, Great Lakes, and Energy.

To date the City has performed climate change analysis and gathered data to develop a Flood Model. Results from climate analysis and the flood model can be viewed on the following pages. To inform the model, the City spent several days with the community and issued a survey to residents to gather the data, including options for residents to upload photos of flooding, ways to connect with the City for immediate support, and education to help residents divert water away from their homes.

The City is now focused on prioritizing projects that will form the basis of future projects within the Wet Weather Resiliency Plan. The City hosted two focus groups with key stakeholders in November to gather feedback around project prioritization and are now opening a survey to the public for their feedback.

Explore this Virtual Open House to learn more about vulnerable zones, how you can reduce flooding on your personal property, connect with the City, and provide feedback to support the City develop a Wet Weather Resiliency Plan that works for you!

Timeline

The Wet Weather Resiliency Plan was envisioned by the City to be foundational in helping the community become more resilient to the changing climate conditions.

Eleven tasks were identified to create the plan. Currently, Tasks 1 – 6 are complete, and Tasks 7 and 8 are underway. Stakeholders are being asked to provide feedback at this stage to help the City vet, prioritize, and/or right-set the course if needed.

This is a 2.5 year effort resulting in a presentation and adoption of an actionable plan for the City.

A Changing Climate in East Lansing

In August 2021, 7.22 inches of rainfall fell within the City in the span of 5-6 hours—an event deemed to be as rare as a 1,000-year storm. The event resulted in 227 reported incidents of flooding. Just a month later, in September 2021, the City saw 25 more reports of flooding, this time from a mere half-hour downpour of 1.25 inches. In 2024 two more severe rain events, one in June and another in July, would cause widespread flooding. The event in June dropped 5.2 inches in six hours, while the event in July, which was even more intense dropped 6.2 inches in three hours.

These events are a reminder of an uncertain future climate with the potential for increasing frequency of short but intense storms hitting our community. Rainfall like this is not unique to East Lansing as communities across the nation are grappling with the challenges of more frequent, high-intensity storms. In a proactive response, the City has initiated the development of a Wet Weather Resilience Plan (Plan) to find ways to mitigate flooding and safeguard its residents and visitors. As part of the Plan, the City and its consultant HDR have developed The City of East Lansing Changing Precipitation Conditions Report that incorporates the latest scientific analysis using historic and future climate change rainfall. The findings within the report will ensure that future investments as part of the Plan are functional and resilient to increasing rainfall patterns.

What type of analysis was performed?

Historical Trending Analysis. The report analyzed historical rainfall trends using long-term rainfall data from 1949 to 2023 from the Lansing Airport. Over this period the trendline of annual precipitation in the East Lansing region increased approximately 30% (from 27 to 35 inches of rain). Likewise, the historical trends indicate that the intensity of rain events have also increased. For high intensity 1-hour duration rain events, historic trends indicate an almost 75% increase in rainfall from 1949 to 2023.

Engineering Design Storm Analysis. Engineers rely on prescribed engineering design storms to “right size” stormwater drainage systems. These events are the so called “10-year” or “100-year” rain events. Analysis within this report found that the engineering design storm estimates specifically for East Lansing developed by the National Oceanic and Atmospheric Agency, commonly referred to as Atlas-14 Rainfall Estimates, are over 10 years out of date. The engineering design storms were updated for the City using more recent rainfall data. Analysis indicates that by including more recent rainfall data the engineering design storm for the 1 though 25 year rain events all increase, indicating that smaller, more intense, and more frequent rain events are increasing in size.

Representative Storm Analysis. Using high resolution radar rainfall scans, twelve of the largest rain events that have impacted East Lansing in the past 30 years were analyzed for spatial patterns and timing of rainfall. Analysis from these historic rain events, referred to as “representative storms”, indicate that storms that result in flooding in East Lansing are often 3 to 18 hours in duration. Most of the rainfall of these events happens in fewer than two to three hours, with one hour peak intensities overwhelming City drainage system capacities. This indicates that short duration rain events should be a focus for the Plan.

Future Climate Change Analysis. The impact of future climate change was determined using state of the practice Global Climate Models specific to East Lansing. Climate change projections were determined for the years 2035, 2050, 2070, and 2100. Under a medium global climate change scenario, rainfall estimates are predicted to increase by eight percent by 2100. Under a high global climate change scenario, rainfall estimates are predicted to increase by 20 percent by 2100.

What are the key takeaways that you should know about changing precipitation in East Lansing?

Using actual observed data from the Lansing Airport, annual rainfall volumes and single event intensities are both increasing. These increases are incorporated into the engineering design analysis used to develop the Plan.
Analysis of twelve heavy rain events over the past 30 years indicate that rainfall patterns happen in a short intense burst of rain. Most of the rainfall in these events occurs in fewer than two to three hours with one-hour intensities being the primary driver for drainage system capacity. This short duration events are being used to develop the Plan.
Future climate change results in an eight to 20 percent increase in rainfall for the year 2100. This future increase is being used analyze projects that will be included as part of the Plan.

Development of a Flood Prediction Model

The flood model has ability to predict flood prone locations within the public rights-of-way, including depth of flooding and extents, and help City officials understand potential root causes related to the public drainage infrastructure. Future capital projects can also be inserted into the model to understand flood reduction benefits on the public drainage system. Results from the model will help inform the development of the Wet Weather Resilience Plan and prioritize future investments within our most vulnerable neighborhoods.

Below is an interactive map of flood prediction results extracted from model for the July 9, 2024 rain event that dropped over 6-inches of rain within parts of the City within 3 hours. Blue areas on the map show depth of predicted flooding within the City. Results from the flood model were used to confirm the accuracy of the model by comparing the results to survey responses and photos submitted by the public after the event.

Note: The flood prediction model is limited to public infrastructure only such as pipes and roadways. Results from the model do not represent private property flooding issues such as backyard flooding from clogged drains, misdirected roof downspouts, or groundwater seepage through foundations.

Flood Areas of Concern

Results from the flood model were used to identify flood areas of concern. An area of concern was identified as an area that experienced road flooding of 6 inches or greater or building flooding during a present day 25-year, 1-hour storm event of 1.60 inches of rainfall. A total of 58 flood areas of concern were identified across the City.

The areas of concern were then put through a scoring and ranking system to identify which areas are the most impactful to residents, businesses, and City infrastructure. The scoring system included analysis metrics such as number of buildings flooded, depth of flooding in the roadway, proximity to critical facilities such as fire and police stations, and risk for combined sewer backup. Based on the results, the areas were then categorized as either a High, Medium, and Low score for the purposes of the development of the Plan.

The map below highlights the flood areas of concern, as identified through stakeholder feedback and the results from the flood model. The High scoring areas (shown in red) were selected by the City and stakeholders for the first round of concern areas that are being advanced for further project evaluations. Middle and Low concern areas will be advanced as part of other future planning efforts. As part of the project evaluations, it is anticipated that flood mitigation projects identified in the High scoring areas will have the potential to provide systemwide benefits to surrounding neighborhoods and reduce the risk of flooding elsewhere in the City. The implementation of projects in the High scoring areas provide a starting point for the City with the potential to expand projects into the Medium and Low scoring areas.

It should be noted that three areas received a High score but were not selected for additional evaluation under the Plan. These areas (shown as striped red lines) were not selected because they are already being addressed under an existing City project or are the responsibility of another government entity such as the County Drain Commission or Michigan Department of Transportation.

Project Prioritization Using a Community Driven Approach

Within the High-ranking flood areas of concern, concept level flood mitigation project alternatives are currently being identified and evaluated. Evaluations will follow a two-step process:

Step 1

Identify conceptual flood mitigation project alternatives within each area and insert into the flood model to understand flood reduction benefits.

Step 2

Using the results from Step 1, score and rank each project alternative using a project prioritization framework. Select the highest-ranking projects for inclusion into the recommended Plan.

What is the Project Prioritization Framework and how was it developed?

The Project Prioritization Framework was developed in conjunction with the City and public stakeholders who consist of various neighborhood community groups and non-City government entities. The Project Prioritization Framework consists of eight (8) criteria for evaluating projects as part of the Plan. These criteria are shown below. The relative importance of each criteria, referred to as its “Weight”, was determined by using a pairwise scoring approach. A pairwise scoring approach allows the City to understand which criteria matters most to the community when it comes to evaluating projects. A higher weight means that criteria is more important. For example, the highest weighted criteria is “Improved Drainage” with a Weight of 16.5%, while the lowest weighted criteria is “Ease of Constructability” with a Weight of 7.9%. This means that Improved Drainage carries over double the importance as compared to Constructability when evaluating and selecting projects that will be included in the recommended Plan.

In addition to the Criteria, the City has stressed the importance of environmental justice and equity as part of the overall development of the Plan. Analyses have incorporated social vulnerability using publicly available US Census metrics. This data was analyzed to understand where the most vulnerable areas in the City are located and will be factored into the project prioritization and selection.

How do you feel about the Criteria and weights? Please consider submitting feedback by filling out the Survey by clicking on the Feedback webpage on the left panel.

1
Improved Drainage

The degree to which drainage is improved to reduce flood risk.

Weight: 16.5%

2
Water Quality

How aligned the plan is with the City’s Combined Sewer Overflow elimination goals or ability to design project with water quality treatment features.

Weight: 15.5%

3
High Impact

Focusing the City on projects that impact a higher total number of people or a high-visibility project.

Weight: 14.9%

4
City Resiliency Alignment

How aligned with City’s resiliency initiatives will relate to green stormwater management and infrastructure.

Weight: 13.0%

5
Impervious Surface Reduction

Focusing the City on projects that will reduce unnecessary impervious surfaces (cement or other non-draining surfaces).

Weight: 11.8%

6
Impervious Surface Reduction

Focusing the City on projects that will reduce unnecessary impervious surfaces (cement or other non-draining surfaces).

Weight: 11.8%

7
Level of Maintenance

How easy it is to maintain.

Weight: 9.4%

8
Ease of Constructability

How easy is it to build and implement.

Weight: 7.9%

Reducing Flooding at Home

While the City plans and prioritizes projects to address flooding in public systems, residents can also take steps to reduce contributions to the storm sewer system and their homes.

For a greater impact, consider:

Install a rain garden that features deep-rooted, native plants and a depression in the landscape to capture and infiltrate runoff.
Install a rain barrel and connect it to a downspout to save water and use it later.
Consider the impact of impervious surfaces when redoing driveways or adding outbuildings. Use bioretention, porous pavers, or other green techniques to negate increases in runoff.

All of these stormwater tips can help protect your home from flooding, either directly by preventing the pooling of runoff in your yard, or indirectly by reducing your contribution to the storm sewer and therefore lessening the burden on the system. But there are other ways to protect your home against water damage from heavy rain.

To reduce or divert flooding on private property, consider:

Adopt a drain! Keep debris clear of the storm drain catch basins to allow for proper drainage, and/or alert your local municipality of issues with drainage.
Ensure your gutters are clear to avoid water overflowing before reaching the downspout.
Place your downspout discharge at least four to six feet away from the home, which reduces the amount of water near your foundation and basement.
Grade the landscape around your home to move water away, not towards, your foundation. A good rule of thumb is that the ground should drop one inch for every one foot you move away from the house. Build up soil and landscaping to create this downslope.
Use a sump pump and hook it up to a battery backup in case of a power outage.
Consult with a plumber about flood prevention tools like backflow preventors, sewer traps, check valves, and more.

Share these ideas!

It’s also important to share these ideas with your neighbors and support investment in our local infrastructure. If residents, businesses, and municipalities work together to reduce stormwater runoff and improve both our public and private wet weather infrastructure, we can be better prepared for intense rain events in the future. Visit MyWatersheds.org to learn about how communities in Greater Lansing and throughout the country are managing their stormwater challenges and how you can help at home.

Resources

Basement Flooding and Sewer Backup Information
Basement Flooding & Sewer Backup Information | East Lansing, MI - Official Website

Basement Flooding Brochure
Basement Flooding Brochure PDF

Sewer Backup Dos and Dont
Sewer Backup Do's & Don'ts | East Lansing, MI - Official Website

Heavy Rains and Backup Drains
Heavy Rains and Backed-up Drains PDF

Next Steps

The City is currently evaluating potential projects within the High-ranking flood areas of concern. Projects are currently being inserted into the flood model to determine their effectiveness on reducing flooding for both present day storms and future climate storms. Projects currently being evaluated include storm separation, storm and sewer drainage piping improvements, and nature based green strategies to capture and manage rainwater where it falls (for example, rain garden basins in parks and subsurface stormwater tanks under parking lots). Projects will then be scored using the Project Prioritization Framework. We anticipate the results of this evaluation to be completed in late-Spring into Summer 2026. Results will be presented to the public for additional feedback and incorporated into the recommendations within the Wet Weather Resiliency Plan.

In meantime we encourage you to fill out the Survey and provide your feedback on the work completed thus far. We also encourage you to reach out to the City if you have any questions or additional feedback you would like to make in addition to the Survey.

Thank you for your participation and we look forward to your continued engagement on this critical project that will shape the future of the City.