Old Cottonwoods stand tall in Water Works tree grove
September 1, 2015 by Janette Law
It’s been proven the world over that nature will fill-in cityscapes that humans have abandoned. Such an evolution is playing out on the Water Works site, where a grove of volunteer trees has overtaken a man-made slope that tumbles from First Street to West River Parkway. This grove is about a block long and some 30-60’ wide and entangled in the mill ruins buried there.
Throughout the Water Works design process, community members and designers have agreed that the character of this grove should be preserved. In particular, three mature cottonwoods lend grandeur to the grove that matches the site’s perch on the mighty St. Anthony Falls.
On August 19, MPF’s Bruce Chamberlain, along with Minneapolis Park & Recreation Board Planning and Forestry Staff and a Minneapolis Tree Preservation Commissioner conducted an on-site tree assessment and brainstormed ideas for preserving the grove, and especially, the “signature” cottonwoods. We asked Bruce to tell us a little about what they learned.
(JL)Would you please describe this little urban woodland?
(BC) In the grove, there are roughly 55 trees over six inches in diameter – about 32 cottonwood, 18 box elder, and five Siberian elm. The three signature cottonwoods are all over 36” in diameter. There are also numerous trees less than six inches, mostly box elder and ash. Unfortunately, some of the trees are growing on top of or out of the base of designated historic mill ruins, which are intended to be restored as part of the park design. The tree roots are destroying the foundation walls.
What did you learn about the cottonwoods?
The outcome of the initial tree assessment is largely promising. Two of the three signature cottonwoods are healthy and are believed to have minimal or no impact to mill ruins. The third signature tree is in decline and is growing on top of a buried mill ruin. Roughly 20 other trees in the grove are believed to be seriously impacting mill ruins. We recognize that some removal of existing trees will be necessary to halt damage to mill ruins.
The grove is an important feature of the Water Works current concept. How will this assessment affect future plans?
Recognizing the importance of the grove, the current Water Works design contemplates a combination of tree preservation and new tree planting. The assessment led to a determination that the next phase of park design should explore a few key strategies. 1) Any trees lost should be replaced with sturdy, high habitat-value trees. 2) Alternative, creative approaches to placement and design of the proposed park pavilion should be studied to attempt preservation of one of the signature cottonwoods. 3) Detailed grading and retaining wall strategies should be used to preserve other trees in the grove if they are not impacting mill ruins.
Featured image: MPRB forestry staff at the Water Works site