Greenseams^® at 25: Protecting Land, Safeguarding the Future

Celebrating 25 Years

of Greenseams

What Happens Upstream Affects Everyone Downstream

Water moves downhill. Every raindrop that falls upstream has the potential to affect people and places downstream. Natural areas in the upper watershed are especially important because they slow, store, and help manage stormwater before it reaches rivers, streams, and neighborhoods downstream.

For 25 years, Greenseams has protected wetlands, floodplains, and open spaces that naturally absorb and store floodwater across the Milwaukee region.

That work is becoming increasingly important. Between 2000 and 2022, flooding caused an estimated $207 million in damage across the region, and recent events in August 2025 and April 2026 showed how quickly heavy rain can impact communities.

Nearly 95% of Milwaukee County’s natural land has been lost or altered. With fewer natural areas absorbing rain, more water runs off the land and into streets, streams, and rivers.

Current Wetland Data: Left side of map

This feature layer displays wetlands of the United States from the National Wetlands Inventory produced by the US Fish and Wildlife Service, updated by Esri annually.

Historic USGS Hydro Data: Right side of map

In 2012 a joint project was started by MMSD and University of Wisconsin –Milwaukee (UWM) to support MMSD’s Integrated Regional Stormwater Management Program. Water features were identified and digitized from scanned source maps. These features included: Stream lines, River lines, Lake Michigan Shoreline Pond boundaries, Lake boundaries, Swamp or marsh boundaries Spring locations.

Source maps used for the project included: U.S. Geological Survey, 1901-1906, and USGS Historical Topographic Quadrangle Maps.

Flooding is Connected

A watershed is an area of land where all precipitation, rain, and snowmelt drain downhill into a common body of water, such as a river, lake, or ocean.

Recognizing that flooding is connected across the watershed, MMSD shifted its approach in the 1990s. Instead of focusing only on moving water away as quickly as possible, MMSD began managing water across the entire system.

Today, MMSD manages flooding using a watershed approach that combines engineered infrastructure, development policies, ongoing maintenance, and natural infrastructure like Greenseams. Together, these investments reduce flood risk throughout the region.

By preserving natural areas that absorb and store stormwater, Greenseams reduces the amount of runoff flowing downstream during heavy rains. Protecting these lands is often one of the most cost-effective flood management strategies because every gallon of water stored upstream is a gallon that does not need to be managed through more expensive engineered solutions downstream. Investing in enough Greenseams properties can reduce the need for future flood storage facilities, channel improvements, and other infrastructure projects while providing additional environmental and community benefits.

Greenseams: Managing Floodwater Through Land Conservation

Greenseams® is an innovative flood management program that permanently protects wetlands, floodplains, and open spaces with water-absorbing soils. These natural areas allow rainwater to soak into the ground instead of running off into streets and waterways. This also helps improve water quality by filtering pollutants before they reach streams and rivers.

The program focuses on protecting undeveloped land in areas expected to see future growth, keeping them open so they can continue to store and slow stormwater naturally. Lands are protected through the land conservation model, where land or the interests in land are permanently protected through acquisitions and easements from willing private landowners.

By preserving these lands, Greenseams helps maintain the watershed’s natural ability to manage water while also supporting cleaner water, healthier ecosystems, and open space for future generations.

The first Greenseams acquisition is a conservation easement purchased in August 2002 in partnership with the City of Brookfield. Referred to as the Knull site, Underwood Creek flows through the wooded wetland. The City of Brookfield purchased this property to protect the existing floodplain, the floodwater storage, and the environmental corridor. Photo taken April 2026.

Twenty-Five Years of Impact

The Greenseams program’ 3.3 billion gallons of storage capacity is enough water to fill up the Milwaukee Brewers’ American Family Field 40 times!

Over the past 25 years, Greenseams has protected some of the region's most important natural flood storage areas. Working with willing landowners and local partners, the program has:

Permanently preserved more than 6,105 acres of land.
Protected 167 properties.
Planted more than 118,000 trees.
Transferred 41 properties and 1,320 acres to municipal and land trust partners for long-term stewardship.
Supported important habitat for native and at-risk wildlife, including:
- Henslow’s sparrow (state threatened) – A grassland-nesting species benefiting from prairie restoration on Greenseams sites, including documented nesting in the City of Oak Creek.
- Forster’s tern (state endangered) – Observed on a Greenseams site in the City of Franklin and likely present at other locations.
- Great egret (state threatened) – Occasionally seen across Greenseams sites, including large concentrations at the sites in the Town of Farmington and the City of Oak Creek following flooding events.

These protected lands are spread across the region, forming a network of natural areas that store stormwater, improve water quality, and support healthier ecosystems. Greenseams illustrates that both land conservation and development can coexist.

"It's never a mistake to leave land, forest or field, in its natural state. I got tears in my eyes during the closing, knowing that this was the right decision for our family's land. It will remain a visual reminder of how our family came from the land, farmed the land, treated the land with respect, and loved the land." - Tracy Senbeil of West Bend, WI

"Land has been in our family for six generations and holds deep meaning for the entire family. It is a good feeling to know that the land will never become a parking lot or large subdivision." - Kurt and Sarah Gruetzmacher of Grafton, WI

Partnerships That Make It Possible

Greenseams is a watershed program that is implemented through a network of partners who help make long-term land protection possible.

MMSD works with The Conservation Fund and Pheasants Forever, two national nonprofit conservation organizations that help communities protect land and water resources to implement the Greenseams Program. The Conservation Fund completes landowner outreach, land acquisitions, and secures public and private philanthropic capital for acquisitions and land management. Pheasants Forever completes land management, site monitoring, volunteer and hunter experiences, and secures funding for land management.

Greenseams is supported by funding partners that make large-scale land protection possible, including U.S. Fish and Wildlife Service, USDA-Natural Resources Conservation Service, Wisconsin Department of Natural Resources Knowles-Nelson Stewardship Program, Wisconsin Coastal Management Program, and Fund for Lake Michigan. These partners have leveraged MMSD capital funding by roughly 30%.

MMSD coordinates with local government and land trust partners to verify that potential Greenseams acquisitions coincide with their land-use and organizational goals. Once land is protected, sites are often transferred to these partners for the long-term care. Partners include the municipalities of Brookfield, Brown Deer, Franklin, Germantown, Mequon, and Oak Creek, park systems of Ozaukee and Milwaukee Counties, state agency of Wisconsin Department of Natural Resources, educational organizations of Mequon Nature Preserve and Riveredge, and land trusts of Cedar Lakes Conservation Foundation, Glacial Lakes Conservancy, Milwaukee Area Land Conservancy, Restoring Lands (formerly known as River Revitalization Foundation and Ozaukee Washington Land Trust), and Waukesha County Land Trust. Of course, Greenseams® would not be possible without willing, private landowners who have a direct connection with the land and place their trust in MMSD to provide perpetual protection.

Greenseams also partners with the University of Wisconsin–Milwaukee’s Electa Quinney Institute for American Indian Education to support Indigenous-informed approaches to land management on selected sites, strengthening connections between land stewardship, cultural knowledge, human-land engagement, and long-term environmental care.

Together, these partnerships ensure protected lands continue to function as natural flood storage areas while also supporting healthier ecosystems, water quality, and well-being.

Looking Ahead

Flood risks continue to grow as storms become more intense and development continues. Meeting those challenges requires many solutions working together across entire watersheds, including engineered infrastructure, policies, ongoing maintenance, and natural land protection.

Greenseams is an essential part of that system and as part of MMSD’s 2035 Vision has a goal of preserving over 12,000 acres of natural, key-water absorbing lands. Every acre protected upstream helps protect communities downstream.

As storms become more frequent and intense, protecting the right land today will help reduce flooding, improve water quality, and build a more resilient region for generations to come.

If combined, Greenseams properties would span much of downtown Milwaukee—from American Family Field to the Summerfest grounds, and from Walnut Street to Mineral Street.

Greenseams® at 25: Protecting Land, Safeguarding the Future