Recently we’ve been covering green infrastructure programs locally and nationally. For example earlier posts described the Wisconsin Environmental Initiative’s “Clean Clear Waters Challenge”; and at the national level the Natural Resource Defense Council’s “Rooftops to Rivers” Emerald City program.
So this week people let us dig deeper into the local Green Infrastructure scene and see what’s possible and planned for right here in Madison’s Lake Wingra Watershed. (See watershed map here.) For one thing, students in the Landscape Architecture Department of UW-Madison have produced a set of visionary plans for the Lake Wingra Watershed in general, and for Monroe Street and the Dudgeon-Monroe neighborhood, in particular.
We’ll take a look at these in a bit, but first a refresher. Green infrastructure as you recall is a planning framework and set of strategies for managing storm water in ways that increase absorption of rainfall into the soil and groundwater, reduce runoff and erosion, all the while enhancing the ecological, social, and cultural values that make a neighborhood and city livable.
Green infrastructure is the newer, and creative alternative to traditional “grey infrastructure” and incorporates bioswales, rain gardens, rain barrels, porous or permeable pavement, and plantings of native trees and shrubs that encourage the capture and infiltration of rainfall. (A bioswale is basically a long, narrow rain garden used to slow down and capture storm water runoff.)
Green infrastructure is preventative. It relies on an upstream end approach. Green infrastructure encourages and facilitates the infiltration of rain (and snow melt) close to where it falls–before it has a chance to run downhill and scour the landscape on its way to, oh, say, the Arboretum and Lake Wingra.
“Grey infrastructure” on the other hand is the traditional method of storm water management and relies upon such tools as storm water conveyance pipes, culverts, rip-rap, concrete channels, and detention ponds. And lately, the addition of aluminum sulphate to storm water to capture and settle out sediment and phosphorous and bury them on the bottom of storm water ponds.
Grey infrastructure is an “end of the pipe” or reactionary strategy. Grey infrastructure bypasses upstream opportunities to capture and infiltrate rainfall and postpones action until storm water reaches the downstream end of the pipe and dumps the storm water into a receiving body of water–be it a stream, detention pond, or lake.
Alternatives to Grey Infrastructure Stormwater Management Needed and Proven Feasible
Any integrated watershed stormwater management approach must rely on a mix of green and grey infrastructure–it is not likely that either one of these approaches, used in isolation from other approaches, will solve all of a watershed’s problems. The problem in the Lake Wingra Watershed is that storm water management is weighted heavily toward the grey infrastructure end of the scale. Grey infrastructure is used–at the municipal level–to the near exclusion of green infrastructure.
Each of the six constructed storm water detention ponds in the UW-Arboretum uses traditional storm water management techniques–straight, rip-rap channels, concrete box culverts, and detention or settling ponds. Only one–Pond #2 in the SE corner of the UW-Madison Arboretum–has bioswales as part of the design. And we are not even counting Lake Wingra which is itself a large storm water detention pond. Lake Wingra receives direct storm water flow from the Pickford Street outfall and from a storm drain in the Town of Madison in the Arboretum.
There are a few rain gardens scattered about the watershed but most are on commercial or residential property and few, if any, are on public lands. Recent figures from the LA 920 project show that there are 25 city planned or installed rain gardens in the Lake Wingra Watershed; and over 35 homeowner installed rain gardens. True, each of these rain gardens helps and is an increment of improved rainfall infiltration, but they are not enough and are not part of a larger, watershed wide planning approach to conserving precious rainfall and other natural resources.
New Visionary Plans for the Lake Wingra Watershed
Just when we were about to give up hope we discover that there are two new unofficial planning documents from students in the UW-Madison Landscape Architecture Department that propose design plans for incorporating green infrastructure in the watershed. These planning documents are richly illustrated with real-life examples of innovative design and management techniques used by cities and towns across the country to manage storm water in an enlightened way. If you want to be inspired please read these two documents.
First, from 2011 comes, “Lake Wingra Watershed, Design Strategies for a Healthy Watershed”, by the LA 920 Regional Design Workshop. This comprehensive planning and design document focuses on opportunities for green infrastructure. Click here for the document. This plan examines the wider watershed opportunities for green infrastructure and uses real case studies from around the country of municipalities that have successfully incorporated green infrastructure in their public works.
Next up is the capstone project from Jody Schimek in the Landscape Architecture Department. Her work in this 2013 study examined the potential for , “Design for Healthy Neighborhoods and Lakes”, using Monroe Street and Wingra Park, as a case study. Click here for the document.
This study is timely as Monroe Street is scheduled for reconstruction in the next year or two. If green infrastructure design principles are not used this time, it will be another generation or two before we have another opportunity to make sensible improvements to the way we manage our watershed.