The future of the aging impoundment off North Main has been debated for years. Rowers want the pond preserved and dredged, while the Huron River Watershed Council advocates removing the dam to restore the river’s natural flow. Now the debate is about to boil over: the Michigan Department of Environmental Quality has given the city until December 31 to decide whether to tear down the ninety-five-year-old dam or repair an old earthen embankment attached to it. According to Matt Naud, Ann Arbor’s environmental coordinator, either way it’s going to cost city taxpayers $250,000 to $500,000.
Engineers at the MDEQ Dam Safety Program aren’t worried about Argo Dam itself, which they say is in good condition. The problem is a 1,450-foot-long earthen embankment built to divert water from Argo Pond to a hydroelectric plant by the Broadway Bridge. The plant no longer operates, but the millrace is used by canoeists to portage around Argo Dam, and joggers use a dirt path on top of the embankment to reach trails around Argo Pond.
MDEQ engineers say the city must clear the ten-foot-wide embankment of brush and trees and clean out or replace about sixty drainage pipes, called toe drains, which keep water from building up inside the embankment. Most of the toe drains are clogged, buried, or missing, according to Byron Lane, chief of the Dam Safety Program. Without functional toe drains, he says, the embankment is in danger of becoming saturated and collapsing, especially if a tree falls over and pulls a big chunk of dirt out with it.
“Our concern is that the dam could fail, releasing the entire contents of the impoundment pond in a flood wave downriver,” Lane says. “In Ann Arbor’s case, there are occupied buildings downstream from that dam. You’re talking about a hazard that could affect people’s lives and property.”
Sumedh Bahl, who manages the Ann Arbor water treatment plant, is responsible for maintaining Ann Arbor’s four city-owned dams. Bahl says his staff is keeping an eye on the embankment and “has seen nothing to suggest there’s any danger.”
While they agree the toe drains need work, Bahl and other city officials want to postpone fixing them until city council decides what to do about Argo Dam. “It doesn’t make sense to spend money to repair toe drains if we’re going to remove the dam,” he says.
Despite the state’s deadline, Naud says the city is planning a series of public meetings in January to “reach out to the community and have a discussion” about possible options for the Argo Pond area and how to pay for them. “The real question is how much is this pond worth to us as a community,” he says.
Those discussions had better happen soon, says MDEQ’s Byron Lane. He says toe drain problems have been cited in Argo Dam inspection reports since 2001.