June 2025: Lake Katherine’s Last Check Up

Wisconsin is truly fortunate to have a system of government agencies and non-profit organizations that support the health of its thousands of lakes.  In Oneida County, the County Government supports a robust Land and Water Conservation Department with the following duties: 

“The Land and Water Conservation Department (LWCD), works in cooperation with a committee of elected supervisors to conserve the land and water resources in Oneida County, and meet local soil, water and related natural resource priorities. Healthy lakes and habitat improve every aspect of life in the Northwoods, from fisheries to recreation to tourism to choosing real estate! Using proactive conservation planning, we can successfully manage our clean air, soil, and water, so that our region will be a better and healthier place for future generations of Oneida County residents.”

Like any good approach to health, a check up by professionals now and then is in order. The Aquatic Invasive Species program is one within the Oneida County LWCD. Last summer on two days in late July, the AIS program conducted an early detection survey for aquatic invasives (plants and animals) and conducted water quality monitoring for three parameters - water clarity, dissolved oxygen, and water temperature. With so many lakes in the county, these are done on a periodic basis, not every year.

The AIS program created a report that can be accessed here: 2024 Aquatic Invasive Species Early Detection Monitoring Water Quality Report. It is well worth reading in its entirety, but if not, at least the introduction and summary as well as toward the end where there are photos and descriptions of the existing invasive species as well as of some of the most common native aquatic plants.

The top line summary is that Lake Katherine does not have any new invasive species and that the water quality remains quite high.  This is great news we should all be happy with and proud of.  At the same time, there are trends and other information that should trouble us and move us to action.

One disturbing trend is that despite several decades of volunteers finding and trying to control or eradicate purple loosestrife, it is still found in many places around the lake. The County AIS crew clipped flower heads or pulled out loosestrife plants as did a few lake property owner volunteers.  A prolific seed producer, loosestrife has to be dealt with every year.  One missed year means that hundreds of thousands of seeds are set afloat, some of which survive and establish new infestation sites.  Additionally, existing clumps of plants expand through underground rhizomes and older plants grow even deeper and stronger root systems making them more difficult to dig or pull out.

The same can be said for yellow iris, other than up until last year there was no coordinated effort to try to manage the rapidly expanding numbers of these plants along the lakeshore, especially in the northern reaches of the lake.  We are starting at a greater deficit with yellow iris and need to put more effort into eradicating this plant. It grows in both shallow water and on the shoreline.

The County’s report did not speak to several invasives because they are either not aquatic in nature or are no longer considered an “invasive” based on state status (much like we no longer think about house sparrows as invasive and consider them “naturalized.”)  One is aquatic forget-me-not, which forms dense mats along the shoreline and was found in high numbers in a handful of areas last year by volunteers.  While the state no longer invests efforts into looking for or treating this plant, we’d be wise to not give up on trying to keep it under control if we can’t totally eradicate it.   Another is Japanese honeysuckle, which grows along the shoreline in just a few paces, but without treatment will have its seeds (carried by birds after eating the fruits) spread to other areas, negatively affecting the integrity of our lakeshore forests.  Similarly, Japanese knotweed has been found in three places in the highway right-of-way near the old wayside near the Lake Katherine bridge.

This summer, the Board will be engaging with the County and with the Northwoods Land Trust as some of the invasives are found on the shoreline areas of the Yawkey Forest Reserve parcels.  If you have yellow iris and/or purple loosestrife on your lakeshore and would like to report it or have it removed, please contact Board President Paul Strong at (pivstrong@gmail.com).

The County’s Land and Water Conservation Department has a great website with loads of information on topics from Wetlands to Protecting Your Shoreline to Aquatic Invasive Species at:  https://www.oclw.org/