Geology of the Grand Traverse Bay region, including the Boardman River
The Grand Traverse Bay region has a rich and complex geologic history. During the last glacial advance, glaciers carved deep valleys into the shale and limestone bedrock and deposited enormous sediment accumulations known as glacial till. Glacial till is the mixture of rocks, boulders, and soil picked up by a moving glacier and carried along the path of the ice advance. Glaciers deposit till along their path: on the sides of the ice sheet, at the toe of the glacier when it recedes, and across valley floors when the ice sheet melts. Glacial till deposits are akin to the footprint of a glacier and are used to track the movement of glaciers. Glacial till deposits can be good sources of ground water, if they do not contain significant amounts of impermeable clays. Some of the glacial till deposits in the Grand Traverse region are as thick as 1,200 feet. Sediment characteristics in the area vary widely, in some areas changing from thick, lacustrine clay to a coarse-grained moraine within a few hundred feet. Elevations range from a low of 484 feet above sea level to a high of 1,543 feet above sea level. Some of the highest and steepest sections in the area are located in the headwater areas of the Elk River Chain of Lakes and Boardman River.
The Boardman River Dams
One of the ways man can dramatically change nature is by creating dams on natural rivers. Such is the case of the Boardman River, where there are currently four dams within the last ten vertical miles before the Boardman River empties into the Grand Traverse Bay. This Earthcache is at the site of the Sabin Pond dam, which is on the north end of the Sabin Pond on the Boardman River. After much controversy, the decision has been made to return the Boardman River to its natural state in this area by removing this dam.
Of the four remaining dams, three continue to produce electrical power today. All three dams are operated by Traverse City Light and Power (TCLP). Two of the dams are leased from Grand Traverse County, the other is owned by the City of Traverse City. Traverse City Light and Power has announced that they will cease power generating activities at these sites because the operations are no longer economically viable. As a result, decisions will need to be made by the owners of the dams – Grand Traverse County and the City of Traverse City – about what the fate of the dams will be. Under this project, the Boardman could become the site of one of the first system-wide, comprehensive rehabilitation projects in Michigan built around the restoration of a more natural hydrologic regime. This would be accomplished if decisions are made to remove up to four dams. In that event, restoration of these impoundments to riverine systems would occur and programs would be designed and implemented involving the ecological, institutional, educational and recreational factors that influence the sustainability of the river system.
The Boardman River Watershed
The Boardman River watershed encompasses 287 square miles in the northwestern lower peninsula of Michigan. The river flows through the cities of Kalkaska and Traverse City and empties into West Grand Traverse Bay. The Boardman contributes approximately one-third of the water volume to the Bay, which was recognized in 1998 by the U.S. EPA as one of the most pristine freshwater bays in the world. The Boardman River is considered one of the top-ten trout streams in Michigan with more than 36 of the system’s 179 river miles designated Blue Ribbon river sections. It is also a “State Natural River” which provides additional protective zoning. The river benefits from considerable public land ownership (approximately 50%) along the corridor. It has an exceptional brook and brown trout fishery, and in the lower reaches, supports substantial runs of migratory fish from Lake Michigan such as steelhead, salmon, brown trout, and lake trout.
Boardman River – Past and Future
Despite these distinctions, the full potential of the river is limited by historic and current activities. Originally known as the “Ottawa” after the local band of Native Americans, the river’s name was changed in recognition of timber baron Captain Harry Boardman who was in the area for three years (1848-51), before selling his timber rights to the eventual real timber barons of the area, Hanna & Lay. Like many rivers during the mid to late-1800’s the Boardman served as a conduit for millions of logs during the height of the logging era. These activities had the now familiar, but devastating impacts on river habitat by incising the channels and removing in-stream debris that provided structure and cover. These activities also helped drive Michigan’s native grayling fishery to extinction. In the late 1880’s, five dams were constructed on the Boardman River, including Boardman Dam in 1894, Union Street Dam in 1867, Sabin Dam in 1906, Keystone Dam in 1908 and Brown Bridge Dam in 1921. In September 1961, Keystone Dam washed out, nearly taking Boardman and Sabin Dams as well. Over the years, several other smaller dams on tributaries to the Boardman also failed, including Captain Boardman’s Mill Dam on Kid’s Creek and a mill dam in Mayfield on Swainston’s Creek.
In April 2009, the decision was made to remove three of the four dams, leaving only the Keystone dam to deter sea lampreys from entering into the Boardman. Once the three dams are removed, the only dam on the Boardman River will be the Union Street dam on a river that forms in Kalkaska County and flows westward before emptying into Lake Michigan. We’ll see if that ever happens once all of the special interest groups get involved! DAM IT… OR NOT???
The site of this Earthcache is at the Sabin Pond Dam, one of the dams for which removal is being considered. To log this Earthache, please do the following:
1. Post a picture of yourself and/or GPS with your log.
2. [No longer required] Take an elevation reading on the top of the dam and the bottom of the dam. What is the change in elevation?
3. Glacial till is evident at the surface in this area. Describe the primary size and content (sand, gravel or boulders) of the glacier till that you see along the banks and in the river bottom on the lower side of the dam.
Email the cache owner the answers for (3) above.
To learn more about earthcaches, including how to develop one of your own click here Earthcache.org. You can also obtain one or more of the following levels of the Earthcache Masters Program:
BRONZE (log three or more earthcaches in at least two or more states/countries),
SILVER (log six or more earthcaches in at least three or more states/countries and develop one earthcache),
GOLD (log twelve or more earthcaches in at least four or more states/countries and develop two earthcaches), or
PLATINUM (log twenty or more earthcaches in at least five or more states/countries and develop three earthcaches).
 This cache placed and maintained by a member of NMG. Click here for more details. |