Maintaining Water Levels

Lake Margrethe Water Levels

The responsibility for maintaining water levels in all bodies of water within Crawford County falls to the Drain Commissioner of Crawford County, who is the least senior member of the Crawford County Road Commission.  Since the road commission did not have the time or the expertise to manage or operate the dam on Portage Creek, the Lake Margrethe Property Owners Association was given that responsibility by the road commission.  Your lake association has carefully monitored and adjusted the Portage Creek dam for the past 15 years to accomplish and maintain the court-ordered lake water levels.  The 1973 court-ordered lake levels are based upon sea-level readings established by the National Geodetic Vertical Datum of 1929.

From the first of November to the first of May in any given year, dam boards are raised to allow unobstructed flow of water from Lake Margrethe to the Manistee River by way of Portage Creek. This flow of water out of the lake is designed to allow the lake to reach a level of 1133.7 feet above sea level for the winter months,  or 8.4 inches below summer levels.  This action is taken in order to eliminate erosion and to reduce shoreline devastation during the spring break up of ice on Lake Margrethe.  On or about the first of May the dam boards are lowered to help the lake reach 1134.4 feet above sea-level.  This action is necessary in order to accommodate summer boating and recreation on the lake during the summer months.

Observations and measurements to ascertain accurate lake water levels are recorded 40 to 50 times each year.  Levels are recorded at three different locations: the Portage Creek dam, a lake gauge installed at 8669 West M-72, and a cement seawall at the same location. All measurements and any adjustments at the dam are diligently performed by volunteer Joe Porter, whose time we greatly appreciate.  To prevent high water levels on the lake between May and November, the dam boards are periodically adjusted to compensate for heavy precipitation.  There are, however, no adjustments that can be made at the dam that will address the problem of “low” water levels during the months of June, July, August or September.  Nor can lake water levels be controlled during the months of November through May.

The structural integrity of the Portage Creek dam is the responsibility of the Crawford County Road Commission, but your lake association has financed the new system for raising and lowering the dam boards.  Periodic inspections of the dam are conducted by the Northwest Design Group, and any recommendations regarding the dam’s structure are presented to the road commission.  Our road commission has also acted upon recommendations made by the LMPOA.

In the fall of 2003, members of our association had noticed that winter lake levels were too high and the lake was not approaching the court-ordered winter level of 1133.7 feet. Since the lake remained too high for several winters, residents who were experiencing significant shoreline damage and erosion, compensated by installing seawalls along the lake’s shore. On behalf of its members, the LMPOA decided to initiate a study of water hydraulics in Portage Creek and that study concluded with the dredging of the first 60 feet of Portage Creek in 2009. Because of the actions taken by your lake association, winter lake levels have returned to a more normal range and shoreline damage and erosion have been significantly reduced or eliminated.