Weather officials first began regularly recording the temperatures in Grand Traverse Bay in 1851. Tracking water temperatures is important for more than just scientific knowledge; it helps biologists and fishermen predict the movement of fish in the bay as well as the approximate dates they will spawn. In addition, swimmers and boaters need to know the water temperature to enjoy their activities safely. Grand Traverse Bay becomes dangerously cold in the fall and winter, which makes swimming and recreational boating hazardous.
Since data began to be tracked in 1851, the water temperature in Grand Traverse Bay has warmed significantly. In 1993, the bay froze 12 days later than it did in 1851. In addition, the bay thawed 19 days earlier in 1993 than it did in 1851. From 1997 to 2002, the bay did not cool sufficiently to freeze at all, according to The Watershed Center Grand Traverse Bay. Temperatures in the bay have an average range from freezing to temperatures in the mid-60s. Since 1970, the average water temperature in Michigan has risen 2 degrees Fahrenheit.
Warmer water may sound like a benefit to Grand Traverse Bay, but even a 2-degree fluctuation can have a large impact on the environment. Warmer temperatures affect the timing of fish spawning, as well as the surface evaporation rate of the water. Warmer water may encourage algae and other microorganisms to bloom, which may make the water hazardous for fish and swimming, as well as cause respiratory problems for residents with asthma and other respiratory conditions in Traverse City and the surrounding areas.
In addition to the rising water temperatures, Grand Traverse Bay is experiencing problems with invasive species that threaten the native aquatic species and affect water clarity, among other issues. Asian carp, zebra mussels and sea lamprey are just a handful of species that are proliferating in Lake Michigan waters. In addition to invasive species, the urban growth of Traverse City causes higher levels of pollution and contamination in the bay, such as problems with E. coli and mercury contamination.
