Aquatic plants are a critical component of the lake environment. Plants in lakes produce oxygen during photosynthesis, help stabilize shoreline and bottom sediments, and provide habitat and cover for fish and other aquatic inhabitants. The shallow water and soft sediments in Houghton Lake provide ideal conditions for aquatic plant growth and the lake supports a healthy and diverse population of aquatic plants. Over 25 plant species have been identified in Houghton Lake.
Since 2001, extensive vegetation surveys have been conducted on an annual basis to determine the type and distribution of plants in Houghton Lake. Of special concern is a plant called "Eurasian milfoil" (Myriophyllum spicatum). Eurasian milfoil is problematic in that it often establishes early in the growing season
and can grow at greater depths than most plants. Eurasian milfoil can proliferate and spread via vegetative propagation, in which small pieces break off, take root, and grow. It often forms a thick canopy at the lake surface that can seriously hinder recreational activity. Eurasian milfoil generally provides poor fish habitat when compared to native plant species. Once introduced into a lake, Eurasian milfoil may out-compete and displace more desirable plants and become the dominant species.
During the 1990s, Eurasian milfoil spread throughout much of Houghton Lake. By 2001, Eurasian milfoil infested nearly 11,000 acres of the lake and was common to dense in approximately 5,300 acres of the lake.
2020 Canal Treatment Map
The objective of a sound aquatic plant control program is to only remove nuisance and invasive plant species that adversely impact lake ecology and inhibit recreational use. Under no circumstances should an attempt be made to remove all plants from a lake.
Controlling the spread of Eurasian milfoil in Houghton Lake is an essential component of ongoing management efforts. Because of its ability to spread by fragmentation, mechanical harvesting is generally not recommended to control Eurasian milfoil in that it can promote the spread of the plant. Most often, Eurasian milfoil is controlled via the application of a systemic herbicide. Systemic herbicides kill the entire plant, unlike contact herbicides that leave the roots intact.
After several years of study by the U.S. Army Corps of Engineers and others, Houghton Lake was treated in 2002 with a systemic herbicide called fluridone (trade name Sonar) to control Eurasian milfoil.
The fluridone was applied to the entire surface of the lake in two separate treatments spaced approximately three weeks apart. Vegetation surveys of Houghton Lake conducted since the treatment indicate that fluridone was highly effective and Eurasian milfoil has since been found only in small portions of the lake. Annual spot-treatments of Eurasian milfoil beds are being conducted to help prevent re-infestation of the plant. The control of Eurasian milfoil in Houghton Lake has improved recreational use and benefited both the lake ecology and the local economy.
In addition to herbicide treatments,
mechanical harvesting has been
performed to control nuisance growth
of plants other than Eurasian milfoil,
and over 33,000 milfoil weevils
(Euhrychiopsis lecontei) have been
stocked in and around Houghton Lake.
Milfoil weevils feed selectively on
Eurasian milfoil while ignoring other
Monitoring and selective control are
being conducted on an annual basis to ensure Eurasian milfoil does not regain dominance in Houghton Lake.