Can Cream City Teach Bayou City about Flood Mitigation?
The smell of ripe grass. The blinding purples, yellows, and whites of fall wildflowers. The buzz of pollinators deciding which stop to make next on the buffet. These are all elements of a strategic approach to flood mitigation across the Milwaukee, Wisconsin metropolitan area.
US Water Alliance’s One Water Summit Explores Greenseams Program
I was asked to join the Texas delegation at the US Water Alliance’s annual conference earlier this fall. The One Water Summit brings together a wide swath of the water sector in the name of planning and managing all water resources (drinking water, wastewater, and stormwater) as part of an integrated process. Since every single drop has value, it’s only logical to treat it that way.
The week included plenty of time thinking and planning with municipal water departments from Dallas, Austin, San Antonio, and Houston, but day one of the conference featured a number of field trips to different examples of the Milwaukee area’s water infrastructure. I chose to spend my afternoon learning about the Milwaukee Metropolitan Sewerage District’s (MMSD) Greenseams program.
Conservation of Parcels with Low and High Infiltration Rates Help Manage Flood Peaks
There are two broad approaches at the heart of the program: 1) conserve land parcels that are wet under normal conditions or that hold water after a rain event and 2) conserve land parcels with high infiltration rates to get water in the ground quickly. In certain areas, wetlands and prairies also undergo restoration efforts to improve performance even further.
Working together, these approaches mean strategic locations slow and hold water upstream to reduce flood peaks downstream and release it gradually over time at a more manageable rate. This results in reduced flood risk for private property and public infrastructure. A natural approach to flood mitigation!
Financing Programs in Surrounding Counties
Milwaukee County’s location means it lies at the end of multiple rivers flowing together just before they enter Lake Michigan. That also means Milwaukee County and the City of Milwaukee are at the receiving end of every interaction between rainfall and land use upstream, including areas far outside their respective jurisdictions.
As a result, MMSD uses a mix of grants, bond funds, and service fees to strategically implement its program and preserve land not just within its own service area but on upstream portions of watersheds in a handful of surrounding counties. This makes for greater impact in Milwaukee County and also introduces flood mitigation benefits for many more communities throughout a much broader swath of watersheds in the region.
Link Between Restoration and Reduction
For the field trip, our group visited a handful of adjacent former farm fields within the City of Franklin. Over the last couple decades, these have been restored to reintroduce prairie vegetation, reconnect historical hydrological features, and reduce erosion.
As it so happened, our site visit took place just a day after one of the heaviest rainfalls in the region’s recorded history. Despite the downpour, the site was damp but entirely walkable, assuming you’re wearing something like hiking boots and not dress shoes! This site has moderately high infiltration rates, so water drains downward in a hurry. We saw photos from other sites that took the other approach and held substantial water on the surface before slowly releasing it downstream. We very much saw the action in real time.
Beyond Flood Mitigation to Water Quality Improvements, Too
It doesn’t end with flood mitigation, either. Depending on the characteristics of each site in the program and its conservation agreement, there are additional big benefits via ensuring clean drinking water, preserving wildlife habitat, and providing recreation opportunities for residents and visitors.
At the City of Franklin site we visited, it was obvious the rapidly developing surrounding area was already planning for additional trails to connect new neighborhoods to the site’s open space.
How Ideas Could Translate to Houston
You may be thinking that sounds all well and good for Milwaukee, but how about the Southeast Texas?
Houston locals spend a lot of time talking about the impermeable soils of our region. Yet according to the U.S. Department of Agriculture’s Natural Resources Conservation Service, the soil infiltration rates (how fast water moves down through the soil) of Harris County and Milwaukee County are actually quite comparable.
Granted, data from the National Weather Service’s Atlas 14 makes it clear that the intensity of rain events in Houston is much greater than in Milwaukee.
However, two more things that Houston and Milwaukee do have in common are increasing trends in precipitation intensity and a rapidly growing urban footprint. These two compound each other, with heavier rainfall on ever greater hard surfaces causing more and faster runoff.
MMSD works with local land trusts in its region to make Greenseams a success. In the Houston region, groups like Bayou Land Conservancy, Coastal Prairie Conservancy, Galveston Bay Foundation, and Houston Audubon all play big roles in delivering benefits for flood mitigation and clean water supplies through land conservation from the very top of to the bottom of our region’s watersheds.
The need is definitely present, and the pieces are there to make it happen. I guess you could say it sure “seams” like heartily pursuing such a regional strategy would be a great idea for Southeast Texas too.
By Dr. Matthew Berg, CEO & Principal Scientist, Simfero Consultants. Posted on 12/9/22
1928 Days since Hurricane Harvey
Note: Milwaukee is known as Cream City for the distinctive light color of the bricks produced there and widely used in its architecture.