Help create the new Glacial Valley Park in Woodbury-Cottage Grove

On the border of Woodbury and Cottage Grove, 250 acres of restored prairie and oak savanna form the heart of the South Washington Watershed District’s conservation corridor. This protected open space, known as Glacial Valley, provides important wildlife habitat and also functions as a regional infiltration basin that protects surrounding neighborhoods from flooding.

Aster in fall at Glacial Valley Park

Volunteers have been working to restore prairie and oak savanna at Glacial Valley for ten years, but until recently, the site was mostly inaccessible to the public. Now, the South Washington Watershed District is working with the cities of Woodbury and Cottage Grove to add trails and a pavilion for educational programming. The watershed district is also calling volunteers and community members to help envision a future for the park.

I first visited Glacial Valley during an Arbor Day planting event in 2015. At the time, Dr. Suess’s The Lorax was a big part of our family’s life. After reading it for the first time, my son Charlie (then three years old) wanted to read it again. And again. And then again. When I learned that Great River Greening and South Washington Watershed District would be planting oak trees in the savanna, I told Charlie about it, saying, “Charlie! We’re going to plant trees – truffula trees! Just like in The Lorax.”

Planting trees – Arbor Day, 2015

Though planting day was cold, rainy, and actually rather miserable, Charlie was thrilled. He brought his shovel and a bucket to collect worms, and took it upon himself to personally bring good tidings and cheer to every single volunteer around us. Seeing that year’s Arbor Day event through Charlie’s eyes made me realize how important it is to come together as a community to plant trees, rebuild habitat, and fix problems that we see in the world.

The restored oak savanna at Glacial Valley is representative of the native vegetation that once covered most of Washington County. Oak savanna is a transitional habitat between prairie and forest where tall grasses and flowers grow among scattered oak trees. As with prairie, oak savanna is a fire-dependent ecosystem that evolved in places where natural and human-made fire was common. The deep roots of the prairie plants and the thick bark of the oaks enable both to survive fires that kill off most other species of trees and shrubs.

A volunteer removes invasive species from around an oak tree at Glacial Valley Park.

Unfortunately, most of the prairie and oak savanna in the United States has been lost to farming and development.  Today, less than 2% of the original native grasslands in Minnesota still remains.

South Washington Watershed District’s conservation corridor is the result of two decades of work to create habitat connections and protect land-locked portions of Woodbury and Cottage Grove from flooding. The sandy soils at Glacial Valley are capable of capturing 1500 acre feet of stormwater runoff (enough to fill 740 Olympic sized swimming pools) during spring snow melt and heavy rains. This water then soaks into the ground, is filtered by layers of soil, and eventually recharges groundwater aquifers that provide a source of drinking water for southern Washington County.

The open space at Glacial Valley can retain all of the runoff resulting from a 6.3″, 24 hour rainfall event over the entirety of the South Washington Watershed District’s northern watersheds under fully developed conditions.

Glacial Valley provides a lifeline for the rapidly developing communities of Woodbury and Cottage Grove and is a quiet space in an increasingly noisy world. It is a place for birds to nest and fox to den. In the future, it will also be a place for people to gather and enjoy the beauty of nature.

To learn more about Glacial Valley and how you can help to restore habitat and develop future programming at the park, attend a webinar on April 26, 6-7pm or walking tour on May 24, 6-8pm. RSVP for both events at

To learn more about the South Washington Watershed District and its work, visit