Traverse City Record-Eagle


April 1, 2012

The Boardman, shaped by glaciers, dams

Created by glaciers, river was changed by logs and dams

Editor's Note: First of a three-part series.

TRAVERSE CITY — If Grand Traverse Bay is Traverse City's front door, then the Boardman River Valley must be its backyard.

Bay and river share a long history, one that started about 16,000 years ago when the fourth and final ice-age glacier slid over what today is Michigan.

A mile thick in some areas, the glacier cut deep into the shale and limestone bedrock, then left behind steep hills, ravines and valleys as it retreated 10,000 years ago.

It created the Great Lakes. It dug out northern Michigan's inland lakes and its cold and clear groundwater-fed rivers and streams: the Boardman, Manistee, Au Sable, Betsie, Jordan and others.

The Boardman, once a tributary to the Manistee River, today flows through a 6- to 14-mile-wide rolling outwash plain located between two moraine ridges.

The ice sheet also dropped glacial till — gravel, sand, silt and clay sediment — that ranges from 100 to 1,200 feet deep.

A sandy soil, today called "Kalkaska soil," formed in the glacier deposits. It is so prevalent in the Upper and northern Lower Peninsulas that the Legislature declared it the state soil in 1990. It is found in 29 of the state's 83 counties.

Steve Largent, Boardman River program coordinator for the Grand Traverse County Soil Conservation District, calls Kalkaska soil "both a blessing and curse."

It's a blessing because it is porous and drains quickly. It filters and purifies runoff water before it enters the groundwater, the reason why northern Michigan rivers are so cold and clear.

It helps the river keep from flooding during heavy rains. It is why the Boardman River often is called a "stable" river.

The curse? It erodes easily, Largent said.

Kalkaska soil is one key to understanding the Boardman River's past, present and future. It sheds light on how logging and then hydropower devastated the Boardman.

It clarifies why the remnant population of Arctic grayling thrived thousands of years in the Boardman and other groundwater-fed streams, only to become extinct within a century after logging began in Michigan, its only Midwestern home.

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