Why Eurasian Milfoil needs to be controlled

There are a number of very good questions that many of us ask regarding the killing of the Eurasian milfoil in Cazenovia Lake. Why do we spend so much money and effort to kill the Eurasian milfoil? Is it good for the lake? Are we harming the ecosystem by killing the weed? Are we harming the fishing? No one, including the CLA, likes the idea of using herbicides to control the growth and spread of the milfoil however, at this point it is the most effective method that is at our disposal.  In order to answer these questions some background on Eurasian milfoil is required.

Milfoil is not a weed that is native to North America and is not native to Cazenovia Lake. The weed was brought here in ships from Europe and Asia many years ago. Unfortunately, because it was brought here and did not evolve naturally here, there are no other plants or animals that can naturally control it’s spread. If the weed continues to grow unchecked, it will have the following very damaging effects on the lake:

1)    It will grow to levels of roughly 15 feet in most areas of the lake. Therefore, most of the entire shoreline around the lake will have milfoil growing to the surface.

2)    Once the weed hits the surface of the water it will spread out horizontally along the surface edge. This is critically damaging. This will prevent sunlight from penetrating below the surface and will being to kill the plants under the weed as well as the smaller invertebrates, phytoplankton and animals.

3)    This will also kill the native plants that are needed in order to have a balanced ecosystem.

4)    Excessive milfoil also reduces spawning habitat for many species of fish that exist in the lake.

If left untreated, the following sequence will occur once the milfoil takes over large portions of the lake:

1)    The native plants will begin to die because the milfoil will overtake their growing space

2)    Lack of light underneath the milfoil mats will slowly start to kill off other life in these areas

3)    The small organisms (zooplankton/invertebrates, etc.) will begin to die

4)    The small fish population will begin to decrease because they eat these tiny organisms in the water

5)    The large fish will begin to decrease because they eat these smaller fish

6)    The waterfowl that depend on eating the fish will be affected. The bald eagles, blue herons, gulls, ospreys and other water birds feed on the fish

7)    Causes permanent pools for mosquito reproduction

8)    From a recreational standpoint, many boats, kayaks, etc. cannot get through the matts of milfoil.

9)    The perception of Cazenovia Lake along with the home values significantly decrease. Studies have shown that lakes with uncontrolled milfoil can decrease home prices by as much as 19% compared to homes on lakes without milfoil control. This will cause reduced lakefront property taxes which the entire town must make up the difference. This will ultimately cost all people in the Town and Village to pay more in taxes.

 With this said, the lake needs the native plants that grow in the lake. You will see these, they are “grasses” on the bottom, large broad leaf plants near the bottom, or the stringy tall plants. The milfoil looks like an evergreen tree with a red tip. These native plants provide homes for the organisms and fish that live in the lake and provides a healthy ecosystem. The spread of these plants however are kept in check by other native plants that are here correctly via evolution.

The lake has been treated using the herbicide called Renovate for the past 11 years. It has very effectively killed only the milfoil without damaging any native plants. The Town of Cazenovia in conjunction with the CLA hires an outside firm to do a plant survey every year which proves that the treatment is killing just the milfoil while not killing the native plants. Other methods of control such as “weed carp” cannot be used because they eat all weeds indiscriminately and also the DEC will not allow it because Caz Lake has an outlet to Chittenango Creek. Lastly, a study was performed using a “Weevil” which is a bug that eats only milfoil however, that was unsuccessful.

Most importantly, Cazenovia Lake has an incredible ecosystem, there are nesting bald eagles on the north end, many herons, multiple species of waterfowl and an incredible fishery. We attribute this to the control of the milfoil and much of this healthy ecosystem is due to the fact that the milfoil is kept in check and not allowed to grow uncontrollably. 

The great news is that the CLA and Town are looking at a better, more effective, cheaper alternatives to Renovate called ProcellaCOR. This treatment is potentially only needed to be used every 3 years and in much less volume. Because of this, there are less water restrictions, no swimming restrictions and limited irrigation times. This is accomplished because the chemical is so specifically geared towards being absorbed very quickly by the milfoil that the chemical does not get a chance to float and migrate in the water. It is very exciting that the science is improving rapidly in order to provide for better, more effective treatments.

 The CLA will continue its mission to keep Cazenovia Lake an incredible resource and ecosystem for all to enjoy and controlling the milfoil for all to enjoy is a critical component of this. As reference, please see the pictures below which show what Milfoil looks like.