Reinventing Malletts Creek
Planners look upstream.
To grasp the scale and scope of the changes to the Malletts Creek watershed in recent years, visit the two big parks it flows through.
Start at Mary Beth Doyle Park on the city's southeast side. Enter from Birch Hollow Drive and you'll see a twelve-acre wetland with a vast retention basin in its center. Today, ducks are playing in Malletts Creek as it runs below banks covered by milkweed and bulrushes. After a heavy rain, though, the basin fills to the brim, creating a seven-foot-deep pond that holds fifteen million gallons of water for slow release downstream. To the north, at County Farm Park on Washtenaw, rolling meadows dotted with trees slope gently down to water channels and retention ponds.
These and other changes to the watershed cost federal, state, and local governments $7.4 million--but there was another, even greater, cost no one anticipated. That price is engraved on a plaque fixed to a boulder on the bank above Malletts Creek:
"In remembrance of Wayne Mead: This beautifully restored stream and native prairie are testament to Mr. Wayne Mead's daily standard of excellence and are dedicated to those who labor to protect our natural resources."
A foreman in the family business, Mead Brothers Excavating, Mead was killed in a heavy machinery accident on the County Farm work site on December 20, 2011. He left behind a wife, three children, and four grandchildren.
Mead's legacy is a transformed waterway. "We have taken ditches and turned them back into something more resembling natural streams, and re-made the connections to nearby floodplains," Harry Sheehan, environmental manager for Washtenaw County's Water Resources Department, explains in an email. "Now we have channels that are sized for the job we ask of it (flood conveyance) and are big enough to have turns, eddies, grade drops, pool and riffles that provide more stable habitat--AND improve water quality."
At eleven square miles, the Malletts Creek watershed covers nearly 40 percent of Ann Arbor plus parts of Scio, Lodi,
Pittsfield, Superior, and Ann Arbor townships. Its main stem runs from the Dicken neighborhood north of Scio Church to the Huron River at Huron Hills Golf Course. Tributaries and storm sewers flow into it from as far south as the Ann Arbor Airport and as far north as the corner of Washtenaw and South University.
But that watershed isn't what it used to be. "We've changed the landscape," says Sheehan in a phone interview. "With the development over the last forty or so years, the area's about 40 percent impervious now," and those roofs and parking lots shed rainwater once absorbed by trees and fields. That's made Malletts "a flashy creek."
"Flashy" as in "flash flood." "Normally a few cubic feet per second can go through the six-inch pipe that flows into the Huron River," explains Sheehan. "But after a big storm, 800 or 900 cubic feet per second tries to go through that pipe." The backup floods neighborhoods, and the rush of water wipes out wildlife. "When we looked at the food chain," Sheehan says, "we saw only things living there that can do without oxygen: bloodworms and crayfish."
There were also legal issues. "The state said we needed a 50 percent reduction in the amount of phosphorus that goes into the river," the environmental manager continues, "and that means a 50 percent reduction in the sediment that goes into the river.
The county started the Malletts Creek Restoration Project in 2000. Former water resources commissioner Janis Bobrin "worked with Pittsfield and the city of Ann Arbor for the original funding," says Sheehan. "As the project turned from planning into engineering and construction, we were able to capture money from the federal government and the state and from grants and loans that covered everything all the way back to the planning." The big-ticket items were $3.5 million to stabilize 8,700 feet of stream bank and $3.2 million for the vast retention pond at Mary Beth Doyle Park.
In the late 1990s, the city's watersheds were in the news for a different environmental problem: when it rained heavily, sewage backed up into homeowners' basements, including some on Malletts Creek. In response, the city came up with a plan to keep rainwater out of its "sanitary" sewers. The "footing drain disconnection" program replaced drains that had dumped stormwater into sanitary sewers with sump pumps that sent the water into storm drains.
After disconnecting more than 2,700 homes in twelve years, the program reached the Dicken School neighborhood last year. Then, last March, the same storm that spawned the Dexter tornado dropped two inches of rain on the neighborhood in half an hour. Malletts Creek rose out of the storm sewers, temporarily turning streets into rivers and flooding basements with rainwater.
Some neighbors blamed that flooding on the disconnection program, causing city council to suspend it temporarily while studying its progress and its impact on storm events. But since the sump pumps installed so far added only about 1 percent to the water in the storm system citywide, it's unlikely that changing the footing drain program will keep Malletts Creek belowground in the next bad storm.
More realistic solutions may emerge from the county's new Upper Mallets Creek Improvements study. "It's all about how much water fits into the pipes," says Evan Pratt, who was elected to succeed Bobrin as water resources commissioner last November. "And that depends on how much fits into the ground. My job is to get the storm water off the surface, but we can't let any more water out of the area" during a storm.
The first step, Pratt says, is to hold public meetings and knock on doors in the area: "The people who live there know more about their neighborhood than I do," he says. Topographical maps will also be redone, because aerial imagery is "much more accurate now, with millions of points of information on every square foot. And the city is surveying every storm water sewer" with video cameras.
One solution, Pratt says, might be to "find a place to store the water. That could mean adding more catch basins and building more retention ponds. It could also mean developing more green infrastructure like rain gardens and cisterns so storm water soaks into the ground at the source. Or it could mean repaving streets to enhance flow, like the city did on Easy Street off Packard.
"By this summer, we'll have ideas of what we want to study seriously," continues Pratt, "and in a year, we'll have a proposal with numbers and dollars for three or more alternatives we'll have reason to believe will lead to a viable solution."
But, Pratt warns, Mallets Creek will never be tamed completely. "It's arrogant to say we can fix 100 percent of the problems," he says. "We'll solve the vast majority, but there're always going to be basements with water.
"Try to fight water, you're going to be pushing rope for a long, long time."
[Originally published in July, 2013.]