Voorheis Lake Ecology
By Robert Hart, January 2021
Michigan’s Inland lakes have graced the North America landscape for well over 10,000 years. Our lakes provide outdoor recreational opportunities for hundreds of thousands of Michigan residents. Moreover, the thousands of lakes provide unique lake community and lakefront living opportunities that support significantly increased property values. With these benefits comes an obligation to share in the responsible care of a valuable natural resource that is owned, in part, by all of the residents of Michigan. Addressing lake health and watershed issues is an important part of the work of a lakefront homeowners’ association.
The vast majority of Michigan’s natural inland lake basins were formed as the immense continental glaciers of the last ice age retreated northward approximately 12,000 years ago. As they retreated, gigantic chunks of ice were partially buried in the landscape. When the remnants of ice melted, the newly formed basins filled with water forming what are called “kettle” lakes. The high water quality found in most of Michigan’s kettle lakes is attributable to their glacial origins with formation in soils consisting of nutrient-poor sand and gravel.
Voorheis Lake is one of these kettle lakes. Having a size between 180 to 250 acres (depending on which reference cited), Voorheis lake is among the 1,000 Michigan inland lakes over 100 acres in size. The maximum water depth found in Voorheis Lake is approximately 70 feet. The lake is part of the Clinton River watershed with an inlet stream from Lake Sixteen and an outlet stream to Sashabaw Creek and on to Mill Lake. The main water source for Voorheis Lake is natural wells fed by ground water filtered by the sand of the springs. Much of the lake bottom sediment consists of marl (calcium carbonate) precipitated from the calcium-rich ground water.
An inland lake’s capacity to support aquatic plant and animal life defines its overall productivity or trophic state. Inland lakes are categorized according to four distinct categories that denote their stage along a natural aging process. Results from water transparency, phosphorus concentration and chlorophyll measurements taken together give a Trophic Status Index (TSI) value for a lake
- Oligotrophic (TSI < 38) – exceptional water clarity, absence of abundant aquatic plant communities
- Mesotrophic (TSI 38-48) – relatively good water quality stabilized by aquatic plant communities that help sustain water quality with desirable fish species and other aquatic organisms.
- Eutrophic (TSI 49-60) – prolific growth of phytoplankton limits water clarity, supporting large and diverse array of aquatic plants and animals.
- Hyper-eutrophic (TSI > 60) - severly limited water clarity, high nutrient concentration, explosive phytoplankton growth, declining submerged aquatic plant growth, severe oxygen depletion prevents support of desirable fish species.
Voorheis Lake is classified as being in the mesotrophic state.
Aquatic vegetation in Voorheis Lake
Native aquatic plants are essential to sustaining water quality and healthy freshwater fish communities within a lake. Native plants at shorelines and bottomlands contribute to the stability of high quality, productive lakes and minimize shoreline erosion. Most native plants are slow-growing and rarely cover large areas. Some native aquatic plants can become nuisances for recreational activities and must be controlled.
Aquatic Invasive Species (AIS) of plants and animals originally come from another part of the world and can make their way into Voorheis Lake on boats trailered from the great lakes or another contaminated inland lake. All invasive plant species share similar properties: they grow fast and dense, they crowd out the native species and lower their diversity and abundance, they can render a lake unusable for recreation activities. To date, the troublesome AIS plants found in Voorheis Lake are Starry Stonewort, Eurasian Water Milfoil and Curly Leaf Pondweed.
In general, plants require nitrogen, phosphorus, potassium and sunlight to flourish. In a freshwater aquatic setting, the rate-limiting nutrient for plant growth is phosphorus. As such, introducing a pound of phosphorus to the lake water can result in the creation of over 500 lbs. of algae and plant matter. Although Michigan has passed legislation to limit the amount of phosphorus in lawn fertilizer and cleaning products, phosphorus can still enter the lake from garden and shrub fertilizers, street and driveway run-off, bird and animal waste, sewage seepage and bottom sediment redissolution.
In an effort to control AIS and nuisance vegetation, KHA has contracted with licensed aquatic management companies to survey Voorheis Lake and apply algaecide and herbicide treatments with EPA - and Michigan EGLE (MDEQ) - permitted products. Our current contractor is PLM Lake & Land Management Corp. operating under our Michigan permit ANC9805492. In recent years, the lake has been treated 5-6 times per year with 50% of the treatments consisting of only algaecides to control the invasive Starry Stonewort macroalgae. The use restrictions placed on treated water are posted with each application. Treatments are timed so that the lake is safe for swimming on weekends and holidays. Herbicide/algaecide application to the lake is closely controlled for the specific interactions of the chemicals, dosage and timing. The EGLE permittee, PLM, is the only entity to LEGALLY apply chemical products to our lake. Any homeowner application of any chemical to the lake is forbidden.
Residents are responsible for doing their part in keeping aquatic weeds under control:
- Follow Michigan Boater Law for stopping the spread of AIS between lakes
- Limit run-off of plant nutrients into the lake (especially phosphorus)
- Avoid placing grass clippings and leaves into the lake
- Never place any consumer garden weed killers, etc. into the lake
The U. S. Clean Water Act mandates that “fishable and swimmable” waters must be maintained. The EPA has developed water standards based on the relationship between pollutant concentrations and human health effects. The EPA recommends that in areas with high intensity of use by swimmers, weekly samples are taken for bacteria analysis.
Escherichia coli (E. coli) bacteria is naturally present in the intestinal tract of warm-blooded animals (birds, dogs, cats, wild mammals, people). Fecal coliform bacteria (including E. coli) are present in the feces of these animals and can enter the lake water. While some strains of E. coli are harmful to humans, the presence of any E. coli bacteria indicates that the water is contaminated with fecal matter which may contain disease-causing, or pathogenic, organisms.
Aligned with EPA guidelines, KHA samples water in the area of the KHA beach during the warm July, August months. Samples are submitted to the Oakland County Health Division for E. coli bacteria analysis. Whenever the bacteria level is found that exceeds the one-day bacteria exposure limit, the beach will be closed for swimming, warnings posted and notifications will be sent to residents. In these events, the beach will not be re-opened until bacteria levels fall well below the limit value.
Residents are responsible for doing their part in maintaining clean lake water:
- Do not feed waterfowl or other wild animals
- Clean up pet waste promptly before rain or sprinklers carry it to the lake
- All KHA street drains empty into the lake. Do not dump anything into the drains.
- Report polluters to the 24-hour Oakland County hotline (248-858-0931)
Canada Goose Control
Canada Geese are a modern success story for wildlife management. As recently as 1950, the numbers of geese pointed toward their extinction. However the actions of various wildlife agencies have brought a dramatic increase in their numbers in North America. Extremely adept at living in human-altered areas, Canada geese are now nuisances due to the copius amount of droppings. A single goose can defecate every 20 minutes and up to 1.5 lbs per day. In addition to being unsightly and messy, Goose feces is a major contributor to bacteria contamination of lake water. Although much smaller, ducks and seagulls are also contributors to the bacteria load in a lake.
Under permits from the USDA/DNR, KHA contracts with a licensed goose control company for goose egg collection and nest destruction (usually mid-April to early May) and, if necessary, live goose capture and relocation (usually in June). Typically, 35-40 eggs are collected each year and 50 geese were collected during our 2020 round-up.
Residents are responsible for doing their part in reducing bacteria in the lake from fowl:
- Do not feed waterfowl, especially with bread, crackers, etc.
- Do not place bird feeders close to the lake to attract ducks
- Do not have landscaping that is inviting to geese (lawn to water, no bush vegetation that geese fear could hide predators)
- Scare, harass anything that would make geese want to find another home
Swimmer’s itch is a rash resulting from free-swimming larvae of parasitic flatworms which penetrate human skin rather than the normal host waterfowl or animal. The parasite has a two host life cycle involving a freshwater snail and a bird or mammal.
Residents have reported bouts with swimmer’s itch coming from Voorheis Lake. Avoid swimmer’s itch by not swimming where there is an abundance of birds or snails. Do not sit or wade in shallow water for a long period of time.
Michigan Boating Rules and Responsibilities
KHA and Orion Township support marine patrol by an Oakland County Sheriff on Voorheis Lake from Memorial Day to Labor Day. The purpose of the Sheriff is to promote safety and enjoyment of the lake by all residents. Voorheis Lake is classified as “All Sports”. With a 200 acre size, it is imperative that boaters observe safety regulations, especially the counter-clockwise direction of travel rule. Unique to Voorheis Lake is Township Ordinance No. 20 which stipulates that there shall be no high speed boating from 7:30pm until 11:00am the next day.
Sheriff : Marine Div. 248-858-7831; Non- Emergency 248-858-4911; Emergency 911