West Monroe's Peter Mulvaney featured in the Chicago Tribune

West Monroe's Peter Mulvaney discusses the importance of protecting water throughout the Great Lakes Basin at the Wilmette Public Library on May 28.

Because the Great Lakes hold about 95 percent of the country's usable fresh water, protecting them is critical, a water consultant said May 28.

That precious supply must be protected from pollutants and invasive species, particularly in light of climate change, said Peter Mulvaney, senior principal at West Monroe Partners, a water and energy utility consultant.

"The demand for fresh water is expected to grow by 50 percent by the year 2050," Mulvaney explained. "(Lake Michigan) is a very unique asset that we need to be responsible for."

Mulvaney was among the speakers invited by Go Green Wilmette to the Wilmette Public Library to talk to North Shore residents about the impact and issues of the Great Lakes Basin.

In Winnetka, the concern for Lake Michigan water protection is linked directly to the Winnetka Storm Water Management Program, which seeks to construct a tunnel under Willow Road that would filter storm water and route it to the lake.

The plan has faced criticism among Winnetka residents who are concerned that polluted storm water will be routed directly into Lake Michigan, which would have a broader impact among communities along the Chicago shoreline.

"If Winnetka is talking about building a giant pipe to run into Lake Michigan, they really have to think about that within the broader system," said Henry Henderson, Midwest director for the Natural Resources Defense Council. "It cannot be seen as a single, stand-alone system."

Henderson, who gave a presentation at the Go Green Wilmette event, said moving storm water rapidly through the tunnel would create a costly system that may not prevent contaminants from reaching Lake Michigan.

"It's a new source of contaminated water," he said.

But Winnetka Village Engineer and Public Works Director Steve Saunders said May 29 that the village's storm water management system has a multi-faceted approach that would actually result in increased filtration of contaminants.

The plan includes preliminary approaches like source-control measures to maintain sewer systems and regularly clear streets of debris, Saunders said.

"This is to prevent pollution before it starts," he said.

Additional management practices like permeable pavements and rain gardens would also reduce runoff by naturally filtering storm water that might otherwise cause flooding, Saunders said.

"Basically, what these do is sort of mimic the natural hydrologic cycle," he said.

For smaller rain events, Saunders said, lower-volume flows from the eastern watershed would be diverted from the Cherry Street and Elder Lane storm sewers into the Willow Road tunnel. Water from those storm sewers currently does not get treated before being routed to the lake, he said.

Under the proposed management plan, Saunders said this water would be filtered through an end-of-pipe filtration system that would use sophisticated phosphorus-removal engineering and a system to treat the water for sediment, metals and bacteria before it reaches the lake.

"Based on calculations, about 70 to 80 percent of total runoff volume in a year would be treated," Saunders said. "Because we're taking low flow from areas on the east side, the project actually winds up reducing the total amount of pollutants into the lake, compared to the current system."

Henderson said Winnetka would benefit from a more dispersed, less costly infrastructure program than the proposed $58 million Willow Road tunnel project.

The Village Council has directed staff to move forward with bringing in an engineer to perform an independent cost review and value engineering analysis, Saunders said. The village is currently in the lengthy process of obtaining permits for the project from numerous regulatory agencies, he said.

On a more regional note, Mulvaney said Thursday that communities throughout the shoreline in Illinois and Indiana must continuously seek to invest in responsible ways to preserve and protect Lake Michigan water. Legal and science-based solutions like green roofs are just some of the ways communities can prevent the Chicago area from becoming water-stressed in the future, he said.

Although the lake may look vast, Mulvaney said, the water supply is not endless.

"This is a glacial deposit. This is a one-time gift," he said. "Investing in these resources and investing in policies to protect them is absolutely critical."

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