Historical Perspective of Lake Management in Wisconsin
Plant life is generally considered the foundation for promoting a lake’s healthiness—a good thing. However, if plant life becomes overly abundant, it can create an imbalance in the ecosystem and thus become detrimental to the lake—a bad thing. Disproportionate levels of phosphorus in the water chemistry, caused by excessive plant decomposition or fertilizer run-off, can generate uncontrolled algae growth. The introduction of invasive species, either plant or animal, can crowd out or destroy a native plant population which upsets a lake’s ecosystem symmetry. These are but two of the many examples in the history of our state’s lake system that have triggered some form of aquatic plant management program.
The State of Wisconsin has had an evolving history of dealing with plant management. In the late 1800s and early 1900s, plant management programs were manual and labor intensive. Whether it was done by the proprietors involved in the early ice-making business, or the lumber companies to facilitate their movement of cut timber, or by the early developers and recreators, the job involved hands-on plant removal. The mid 1920s saw the introduction and application of chemical herbicides, such as sodium arsenite, to eliminate unwanted plant growth—in one twenty-year period ending in 1969, it was estimated that two million pounds of this chemical were applied to 167 Wisconsin lakes. By the end of the 1960s, sodium arsenite, which purportedly was biodegradable and would quickly dissipate after application, was found to be accumulating in the lake bottom sediments and thus, use of the herbicide was discontinued. Chemical applications did continue however, using other herbicides, such as “2,4-D.” Their ease of availability and potential for indiscriminate use by an ill-informed public has placed ever-growing importance on the development of properly monitored and systematic aquatic plant management programs.
In 1938, under the leadership of Wisconsin Governor Phillip LaFollete, an aquatic nuisance control committee (ANC), a sub-committee of the Committee for Water Pollution Control, was created with the responsibility for the review and regulation of algae and aquatic plant control in public waterways. Over time this committee has gone through various transitions and is now under the umbrella of the WIDNR. The importance of this oversight role significantly increased with the appearance in the mid 1960s of Eurasian water-milfoil. In the early 2000s, the legislature increased the WIDNR’s scope of authority to require the issuance of permits for virtually all plant management methods—chemical, manual, mechanical, and growth retardant systems. An exception does remain that allows riparian owners to be able to clear plant growth—up to a thirty -foot wide swath—on their shoreline and in the affected water.
Of critical importance to any form of plant remediation activity, is the necessity that a formalized, aquatic plant management plan must be in place before any permit can be issued. HFRLA has undertaken this planning effort which was completed in 2016. In the event that our lakes become infected with a serious invasive plant species, our association has taken the first major step to deal with what would be a complex remediation effort.
EVOLUTIONARY CHANGES TO OUR LAKES OF THE HFR SYSTEM
Whether or not there have been significant or evolutionary changes to our lakes’ aquatic plant make-up is a fairly difficult question to authoritatively answer. In 2008-09, full-scale plant sampling was performed for the first time on High and Fishtrap lakes. The results established the first complete baseline inventory of our lakes’ aquatic plants. Similar sampling and data gathering was performed in 2014 to fulfill an objective of our comprehensive lake planning process. Unfortunately, that gives only a six-year period of perspective for comparison purposes, but at a minimum, does establish useful benchmarks.
There have been three undeniable changes or events that have taken place over the last fifty years that clearly have impacted our aquatic plant ecology—the explosive growth of southern naiad, which is considered a native species; the introduction of rusty crayfish into our lakes (timeframe unknown); and the virtual disappearance on Fishtrap Lake of our cabbage weed (claspingleaf pondweed) population in three major areas of the lake.
Southern naiad (najas guadalupensis) inhabits still or slow-moving water and can be found throughout the continental United States. It is an annual plant that not only reproduces from seeds, but fragmentation as well—detached parts can root or survive in a suspended state. It grows rapidly, forming thick, bushy masses which often float to the surface. Whether this plant always existed in our lakes is an unanswerable question. The first noticeable growth occurred in the early 1990s, in the south-eastern corner of Fishtrap Lake, which was the location of several, active resorts. Growth of the plant accentuated in the spring and summer of 2004 and 2006, the years that the lake water levels were lowered to facilitate repairs of the Fishtrap dam. Increased levels of sunlight reaching the plant appear to accentuate growth. In addition, perhaps due to the ability to propagate by fragmentation, the plant is now found not only in all the shallow bays of Fishtrap Lake, but in certain of the shallow areas of High Lake. Our active pleasure- boating and fishing activities between these two lakes provide a convenient vehicle for the transport of plant fragments from lake to lake. During the summers of 2014 and 2015, the lakes experienced a slight reduction in the level of rafting— the surfacing of large mats of the intertwined plant—with some speculation that the higher water levels experienced in those years may have suppressed some level of sunlight penetration, thus slowing the plant’s growth.
Rusty crayfish (orconectes rusticus), also known as “rustys,” were introduced throughout northern Wisconsin in the 1960s. They are identifiable by the reddish colored spots on the sides of their back and the large front claws with black bands around the tips. Native to the Ohio River area, it is speculated they reached our Wisconsin waters via careless anglers who transported them and used them as bait. The WIDNR website sub-page, which tracks invasive species by lake, indicates they were first identified in High Lake in 2002 and Fishtrap Lake in 2006. This author can tell you from experience that they existed in Fishtrap Lake long before 2006. The fact that they were found in the Manitowish River and in Boulder Lake in 1975 is a good indication they were in our lakes much earlier. They are voracious eaters of plant life and the WIDNR has reported that in some northern Wisconsin lakes, they have destroyed most of the aquatic plant life. They are very aggressive and normal fish predators of other crayfish species tend to avoid the rustys because they fight back. Both bass, particularly smallmouth, and yellow perch, will feed on the crayfish, although, due to their size, the perch are limited to the small and immature members of the species. The rustys’ appetite for plant life brings us to the next important change for our aquatic plants.
In the 1960s and 1970s, Fishtrap Lake had a vibrant population of what anglers like to refer to as cabbage or musky weeds (clasping-leaf pondweed). Within the south-east bay and past the points earmarking the bay entrance, which was home to Fishtrap Lodge, Shelter Bay and Nor-wis resorts, there was a dense population of these aquatic plants. Additionally, they could be readily found in the central-west, north-west and north-east bays of the lake, as well as the shallow bar, mid-way between the culvert opening and the eastern-most island. By the 1990s, these plants had all but disappeared with the exception of those on the bar off of the culvert. The plant sampling done in 2009 identified virtually no existence of the plant. Over the next several years, through the summer of 2015, there has been a slow re-emergence of this aquatic plant in a number of the original locations, a positive sign for the future. It is difficult to draw any scientifically-based, cause-and-effect conclusion, but there exists the possibility that either the introduction of the rusty crayfish or the explosive growth of the southern naiad may have contributed to the plant’s disappearance.
AN INVENTORY OF HIGH AND FISHTRAP LAKES AQUATIC PLANTS - 2014
As previously mentioned, an inventory of our lakes’ aquatic plants was made in 2014, utilizing a GPS-coordinate based sampling plan as approved by the WIDNR. The output will give future generations the ability to comparatively analyze changes in our plant ecology against this benchmarked data.