Marl Lake

It is one of the twenty-two interconnected lakes making up the Waupaca Chain-o-Lakes. Marl Lake is also at the top of the chain. But, its most impressive aspect is the deep blue-green water. As one writer on WI River Trips noted, "the water quality is clear throughout the chain and near perfect on the upper lakes". The upper chain is also enhanced by the fact that they are small lakes (in surface area), meaning the main use of the smaller water bodies is by silent sport enthusiasts, paddling and swimming. The spring fed lakes, per the River Trips article, are often termed the finest set of lakes in Wisconsin. Marl Lake is only 14 acres of surface area, but is 60' deep. 

Marl Lake, from pier at Whispering Pines Park

On a recent camping trip at Hartman Creek State Park, we biked from the campground to the state Whispering Pines Park located adjacent to Marl Lake on three different days. From the entry of the Hartman Creek Campground, it is a short 2.5 mile bike ride, on varied and diverse surfaces from pavement to dirt can take one from the campground to the Whispering Pines Park and Marl Lake, nestled below towering pines at the head of the Waupaca Chain-o-Lakes.  A number of homes are about a third of the lake shore, but the Pope State Natural area adjoins the side opposite the homes, and add in the Whispering Pines Park, and the vast majority of adjoining land is public, which provides the forest view. The Pope State Natural area stands in contrast to the almost fully developed shoreline of some of the lakes, particularly those larger lakes in the lower chain. Cabins built at a time before public access was really a concern, have morphed to large homes in many cases. Hence, there is little public access to the chain, and for use, only two boat landings exist on the six small upper chain lakes. A tragedy of the commons, so to speak. The Whispering Pines area was privately owned although it served as a public park; it was later deeded to the state. The lack of access to much of the system means those few places of access, like Whispering Pines, get significant use. Marl Lake also has a boat launch, one of two on the six lakes on the upper chain.

After our first visit this year to Marl Lake, on a Monday afternoon, we then biked northeasterly on Whispering Pines Road and then mainly south on County Q to Scoopers Ice Cream Shop, where we both had a nice sized single scoop dish of Cedar Crest Ice Cream. After enjoying a delicious treat of Wisconsin made ice cream, we then biked back to the campground. We also visited Marl Lake on Tuesday morning about 9:30 am and were pleased to have it to ourselves for about 20 minutes or so. Wednesday we arrived 15 minutes earlier and some joggers were part way through their jog and jumped in the water a few times. Then the traffic really hit. 

Tuesday morning photo of the lake bottom
before the crowds hit

Part of the problem with access, are not just homes, but also geology--the lakes are glacial kettles and are spring fed, with no outlet. Marl Lake is connected to Hartman Lake by a small creek, that is never really navigable. Given the nature of glacial kettles, many of the lakes have steep sides, including Marl Lake. The steep sides limit access, but many homes are built at the top of the slope. Glacial kettles are formed when a block of ice breaks off the glacier and gets buried with debris. Insulated from warming weather, the buried ice will eventually melt forming a kettle. However, it is not the kettle that makes this lake unique so much as the underlying geology. 

Marl Lake is not only the name of the lake, but the name is derived from a type of lake, mainly described by the sediments that are on the bottom of the lake. Marl is a geologic condition mainly due to limestone. What occurs is that the springs bring in calcium carbonate from the limestone, and when dissolved these minerals they "bind-up" dissolved nutrients such as phosphorus which otherwise can lead to excessive algae growth (Marl Lake plaque).  This leads to the intense blue and green color when plants and algae suitable for hardwater "create a stream of calcium carbonate particles during the day due to photosynthesis and the particles drop to the bottom of the lake." During the day, the water and these particles absorb all the light rays from the sun, "except for the blue-green light which is reflected back and this gives the lake its startling color"--that blue green. The color is not evident during the cold weather months when the plants are inactive. In the winter it is just another lake color. The 1914 report noted that "Also, the color of the water is the same as that of typical marl lakes, being a greenish blue in the shallow water and a darker green in the deep water." The color is related to the plant growth and the sun reflection or absorption. 

Looking at lake bottom from end of pier, notice 
how the water color becomes more green in deeper water

Marl Lake is a small water craft haven. Kayakers, canoeists and now paddle boarders will put in and paddle the upper chain. Many will stop at the dock along Marl Lake, scattering their water craft along the shore, or tying them in the water to the dock such that they dominate the landscape. It gets heavy use. There is no beach at Whispering Pines, just a fishing dock, with a sign that no swimming activities are recommended, but many swim. The water is about 3' deep just off the edge of the land, and over 8 feet deep at the end of the pier. The T-shaped pier is a fancy for sunbathers. I think I counted 12 water craft at one time pulled up on shore or tied in the water by the dock. No dogs are allowed, but that does not stop people from letting their dog run free on the dock and near shore. After we departed Wednesday morning, I went swimming at the beach at Hartman Creek and noted that there were as many people on the dock or shore at Whispering Pines as at all of the 350 foot length of the Hartman Creek beach. 

Plaque at the Marl Lake, by bike rack
I took much of the geology and water color in
the post from this plaque

To get there, many drive, a good number arrive on watercraft, and a few (like us) bike. One family group split it up with some arriving by water craft and others by car and had lunch at the picnic area on top of the slope. Another group had three wooden homemade water craft--two canoes, and a kayak. Of course, you get also sorts of people like the older gentleman who said the water was warmer in the top 3" than below. He must have said it five or six times, such that when he left, some swimmers, although swimming activities are not recommended, were making fun of his constant comments about the top 3" of the water. Of course, the water is generally cold what you would expect--it is a spring fed 60' deep lake. In fact, I find the water in Hartman Lake rather cold and wonder if it is colder than some lakes I swam in up north in June and July. 

Marl Lake is a gem within the waterway and ecosystem of Wisconsin. Sanitary sewer system for the homes along the lake shore I am sure has assisted water quality in the region. The marl, with its high calcium carbonate, was once mined out of the lakes and deposited on farm land in the region, as a fertilizer. People have learned much over time, and luckily, the mining does not seem to have damaged the lake.

When I walk in the water by the dock I do not sink, but the surface is somewhat spongy. The consistency of the lake bed, at that location, is like walking on a bike path made of crushed limestone on top of a sponge. If I get several feet away from the dock I can sink a foot or more in the limestone colored "muck." It is almost difficult to pull your foot out. Limestone gives us building material, forms caves, and gives us hard water. It also gives us the unique color of the marl lakes, due to the interplay of minerals in the water, the algae and plant growth, and the sun. We then marvel at nature's creation of color and its interplay in our viewshed.