Invasive Species

Working to Stop the Spread of Invasive Species

An ESLA top tier role in protecting and preserving our shared waters and shorelines is preventing introduction of invasive species and controlling the spread of or reducing known invasives. In addition, ESLA leads research to determine whether previously unconfirmed, worrisome invasives are present. We also are constantly reassessing new control options.

Invasives can be fish, crayfish, bugs, snails, as well as aquatic and shoreline plants. Some of the plants can be attractive, but all threaten to crowd out native species and wreak havoc on natural ecosystems.

Invasive quagga (2022) and zebra mussels (pre-2010), of eastern European origin, have been found in Elk and Skegemog lakes. Mussels eat by filtering phytoplankton from water. Phytoplankton is at the bottom of the aquatic food chain. Take it away and living things higher in the food chain are threatened.

Plant species such as Eurasian Water Milfoil and Purple Loosestrife are present in some shallower waters but ESLA’s aggressive work has kept them under control. So far.

These are reasons why ESLA has actively encouraged trailer boaters at demonstration events at public launch sites to follow a recent state law requiring Michigan boaters to empty bilges, fish and bait tanks and clean hulls and trailers before launching at a new site. At a recent ESLA/Tip of the Mitt boat wash event, ESLA’s lake biologist found a curly leaf pondweed invasive on the mat used to capture the runoff boat wash water.

Our non-profit is using many means to control known invasives. A recent focus is to avoid chemical treatment where possible. For example, our biologist has often been digging out individual purple loosestrife plants, as an alternative, when possible. We’re also examining new ways to choke out Eurasian Water Milfoil. And we’ve aggressively promoted Clean, Drain and Dry at events at public boat launches.

Keep reading to learn more about ESLA’s invasive plant and animal threats.

Invasive Plants

Eurasian Water MilfoilSTATUS IN ESLA WATERS: Largely under control, through spot chemical applications.

WHAT ESLA IS DOING: Examining alternatives to chemical controls, such as benthic mats that have been used in a successful and very expensive pioneering effort on South Lake Leelanau. It brought a massive problem under control, though at great expense. Fortunately, ESLA does not have EWM issues on that scale.

This native to Europe and Asia was first documented in North America in the 1940s. Since then, it has spread to more than 40 states and three Canadian provinces. It has been identified in ESLA waters, primarily in shallow bayous or bays. Eurasian water milfoil causes problems for the ecosystem and for recreational boaters. It tolerates low temperatures and begins growing each year earlier than other aquatic plants, quickly forming dense underwater stands of tangled stems and vast mats of vegetation reaching the water’s surface.

The lake ecosystem suffers because EWM displaces and reduces native aquatic plant diversity needed for a healthy fishery. Infestations can also impair water quality due to dissolved oxygen depletion as thick stands die and decay. A 2014 study of Elk Lake and the Torch River led to EWM chemical treatment in 2015, which continues on an as-needed basis. Irradicating invasives is time-consuming and expensive.

ESLA has worked with various licensed contractors, using chemical and mechanical plant removal. Permission is required of landowners impacted by treatment work.
Please report suspected Eurasian water milfoil to ESLA.

Please report suspected Eurasian water milfoil to ESLA.


Invasive species Purple Loosestrife (Lythrum salicaria) at the waters edge

STATUS IN ESLA WATERS: Relatively controlled, but then again beating PL is like playing the game whack-a-mole. Also, it’s pretty until it’s not because it has outcompeted native plants.

WHAT ESLA IS DOING: Every year, ESLA relies on prior year surveys to focus control efforts whether using chemical alternatives for larger areas of invasion or digging out individual plants to prevent spread.

Purple Loosestrife is an invasive wetland plant that is beautiful, but a major threat. Imported in the 1800s from Eurasia for ornamental and medicinal uses, its prolific reproduction may allow the plants to crowd out all others. PL has been reported in every state but Florida. It is still widely sold as an ornamental. You can even buy it on Amazon. Please, don’t! PL has gained a strong foothold in many North American wetlands, rivers and lakes.

PL can be identified by its purple flowers which bloom from June to September. It has square woody stalks 4-7 feet high. Leaves are heart or lance shaped and flowers have 5 to 7 petals. Due to the long flowering season, PL plants can produce millions of seeds each year. Plants also sending shoots their roots. The underground stems can grow up to a foot each season.

Purple loosestrife was documented on the Torch River, Lake Skegemog and Elk Lake by Tip of the Mitt Watershed Council. There were 12, 18 and 29 locations where purple loosestrife was noted on the Torch River, Lake Skegemog and Elk Lake respectively.

Invasive Phragmites (Phragmites australis) in a wetlandSTATUS IN ESLA WATERS: Not a significant issue, though we remain vigilant because it has thrived in nearby wetlands.

WHAT ESLA IS DOING: Periodic shoreline surveys. The invasive phragmites is similar to, but a major threat compared to native Phragmites. See links at end of this article for more photographic detail on differences.

Also known as the common reed, phragmites is an aggressive wetland invader introduced to the U.S. from Europe in the 1800s. It grows along the shorelines or in shallow water. It can reach up to 14 feet.  It has stiff wide leaves and a hollow stem and drooping clusters of feathery flowers called inflorescences. The flowers emerge purplish but turn whitish, grayish or brownish in fruit. If left uncontrolled, phragmites can take over wetlands to the detriment of native flora and animals dependent on native habitats. Invasive Phragmites are affecting some shorelines on the East Bay of Grand Traverse Bay. The Antrim County Soil Conservation District has partnered with township and property owners in control efforts. A 2009 ESLA shoreline survey of Elk and Skegemog lakes followed by several more surveys identified only native Phragmites.

Image of Yellow Flag Iris (Iris Pseudacorus)STATUS IN ESLA WATERS: It has been spreading to more shorelines since 2020.

WHAT ESLA IS DOING: In 2023, ESLA began encouraging riparians to remove it from shoreline gardens, where — while pretty — it can push out native species.

Yellow Flag Iris is a perennial native to Europe and found at the edges of lakes, ponds, rivers and streams. It can grow in shallow water, too, and spreads easily, displacing native plants. It clogs wetlands and is not a part of the food web.


Here Are Some More Links To Aquatic Invasive Species

Learn more about Harmful Algal Bloom

Here is a link to a Watchlist of Aquatic Plant Invasive Species

To Learn More About Gold Brown Algae – click here

Invasive Animals

At least 25 non-native species of fish have entered the Great Lakes since the 1800s. Because of the Elk Rapids dam, these invasive fish species, particularly the most harmful such as the round goby, sea lamprey, Eurasian ruffe, White perch and alewife have never entered the Elk River Chain Of Lakes (ERCOL). As ESLA participates in the relicensing of the ER dam, we will strongly oppose the inclusion of a fish ladder at the dam that has the potential of allowing any of these invasive fish species into ERCOL.

Warning: Juvenile Asian Carp may be easily confused with common minnows. Purchase your bait only from reputable sources that are routinely inspected by the Michigan DNR – question the seller!

Dreissena bugensis (quagga) Dreissena polymorpha (zebra)

Image showing Quagga and Zebra Mussels side by sideSTATUS IN ESLA WATERS: Quaggas were first confirmed in Elk Lake in 2022. Zebras have been present since at least 2010. Both feed on phytoplankton, the critical lowest tier in the lake’s food chain.

WHAT ESLA IS DOING: Monitoring. Zebra mussel populations, primarily in waters less than 20 feet deep, have nosedived since around 2015. One theory: They ate themselves out of food — phytoplankton. We know less about quaggas, but are continuing to seek help from researchers to determine their spread in the deeper waters of Elk Lake. At this point, there is no known effective treatment, but we’re keeping an eye on federal government efforts to control quaggas in Lake Michigan off Sleeping Bear National Lakeshore. 

Since 1988 when zebra mussels were first identified in the Great Lakes, their expansion — and that of their deeper water-loving cousin, quagga mussel — have wrought havoc on the ecosystems of Michigan’s Great and inland lakes, as well as across the nation. Zebra mussels have been present since at least 2010 in the shallower waters of Elk and Skegemog lakes. In 2022, students and staff researchers from Northwestern Michigan College’s Great Lakes Water Studies Institute confirmed quaggas in Elk. The team came to Elk at the invitation of ESLA to conduct deep-water research. The same summer, a volunteer team with Three Lakes Association (Torch, Clam and Bellaire) made the same disturbing confirmation in Torch Lake.

The invasive mussels are native to areas in the Ukraine and the Ponto-Caspian Sea. They were brought to the Great Lakes in the discharged ballast water of trans-oceanic vessels. The larvae can easily attach to boats, bilges, bait and fish wells and be transported from one body of water to another. Quagga and zebra mussels consume huge volumes of phytoplankton (microscopic algae) by filtering lake water, removing this important food source that is the base of the entire lake food web. Since mussels have invaded, phytoplankton and the phosphorus concentrations that sustain them have decreased, while growth of nuisance algae — such as golden brown algae — has increased.

Round Goby (Neogobius melanostomus) swimming in the waterSTATUS IN ESLA WATERS: A Michigan Dept. of Resources netting crew in 2022 confirmed what a University of Dayton student snorkeling in front of his parents summer home had told ESLA the previous summer — round gobies were present in Elk Lake. It wasn’t a big surprise since gobies, a native of central Eurasia, have been present in the Great Lakes since first documented on Lake St. Clair in 1990.

WHAT ESLA IS DOING: Taking note, not much else to do. As scientific journals, biologists and anglers all know, there’s an upside to round gobies: Smallmouth and lake trout and other fish that feed near lake bottoms love gobies.


Image of a Rusty Crayfish (Faxonius rusticus) in a fish wellSTATUS IN ESLA WATERS: It’s unclear when rusty crayfish, which are native to the Ohio River and its tributaries, arrived in ESLA waters or to what extent they’ve crowded out native crayfish. But they are now found throughout Michigan lakes, rivers and streams and much of the United States. They destroy aquatic plant beds and limit habitat.

WHAT ESLA IS DOING: Encouraging anglers not to bring any non-native crayfish, minow or other bait into Michigan waters and release them purposely or accidentally.  


Additional resources: Invasives

Tip of the Mitt Watershed Council

Michigan Invasive Species List:

CAKE CISMA (Charlevoix, Antrim, Kalkaska, and Emmet Cooperative Invasive Species Management Area)