Don’t pull on Eurasian watermilfoil, Bear Lake officials say

SALT LAKE CITY — The Utah Division of Forestry, Fire and State Lands is asking the public not to pull on Eurasian watermilfoil, an invasive species currently growing in Bear Lake. 

In a Facebook post on Monday, the division explained that Eurasian watermilfoil currently threatens native plants and animals within Bear Lake. It can also clog irrigation pipes and wrap around boat propellers.

The post called the invasive plant “the REAL Bear Lake monster,” a nod to the urban legend of a creature that lives in the lake’s waters. 

Eurasian watermilfoil has green, feathery needles that look similar to those on pine trees. The plant’s stems are reddish, and it often grows in mats. 

Bear Lake Watch, a group that works to preserve Bear Lake’s beauty, said Eurasian watermilfoil also flowers sometimes, sporting petals that can range from hues of cream to shades of purple. 

Brady Long, executive director of Bear Lake Watch, said it can grow in three feet of water and root at a depth of 30 feet.  He compared the stems’ thickness to that of spaghetti.

“It grows these long vines or these long stems all the way down from 30 feet, all the way to the surface, that act as small ropes. And as it grows from the bottom up to the surface, it likes to spread [and] form a canopy, and that way it eliminates all the competition.”

Where did it come from?

Per Bear Lake Watch, Eurasian watermilfoil was first detected in Bear Lake in 2019, although it had already been in the waters for a few years. 

However, it is unclear how it got into the lake, or to the U.S., at all. The USDA website speculates that it arrived in the country between the 1880s and 1940s, and it was likely spread through aquarium trade or watercraft transport. 

Similarly, the United States Fish and Wildlife Service said invasive species often travel from one lake to another by watercraft, such as boats. 

To prevent the unintentional spreading of invasive species, such as Eurasian watermilfoil, the FWS recommended cleaning your watercraft and outdoor gear thoroughly after each use. 

Invasive species don’t only ruin ecosystems. Removal efforts are costly, often adding up to millions of dollars. Furthermore, the U.S. Department of the Interior said eradication is often extremely difficult, if not impossible, once a species has established itself. 

Why is it such a big concern?

Long said Eurasian watermilfoil can grow to the point that it can eliminate all other types of plant life. He said one of the challenges is that it reproduces by fragmentation.

“If a piece is broken off, let’s say, by someone with good intentions going out and trying to pull it out of the water, or, let’s say, a boat driving over it, [or] even fish grazing on it, each one of the small fragments of that plant can grow into an entirely new colony. And so a plant that spreads by fragmentation is a pretty rough situation. And then when you combine it with how rapidly this plant grows, it’s a big concern.”

However, it isn’t just affecting other plant species in the lake. It’s also affecting recreation. Long said it can eliminate the ability to take watercraft around most of the shoreline and the north end of the lake.

“Those thick strands that we described earlier that grow from the bottom up to the top of the water form mats. And [the] strings or strands or ropes that can entangle swimmers, they can shut down boat propellers. They’ve been known to create all kinds of havoc on any form of recreation, whether it’s a paddle board or a kayak [or] a fisherman on the shoreline.”

Long said Bear Lake feeds a $2 billion industry that’s more than just the recreation that happens on the lake.

“When you think about the $2 billion dollar industry that depends on river or water from the Bear River and from Bear Lake, if Eurasian milfoil chokes these irrigation ditches and channels and streams, it could have a dramatic impact on agriculture and farming and ranching.”

How you can help

Long said it’s important that people don’t try to pull the plants up. If it is pulled on or cut, Eurasian watermilfoil can regrow multiple vines, further expanding its harm to the lake’s ecosystem. 

If people want to help, they can report any problems they see on the Bear Lake Watch website.

“We mapped hundreds of locations in the lake where milfoil is, but if you put on a snorkeling mask and you go around those crystal clear waters of Bear Lake, you will find literally thousands of locations where the plant is starting to grow,” Long said. “I don’t think anyone thinks if there’s a chance we could eradicate it. We can control it. We can try to manage it. But, unfortunately, I think Eurasian milfoil is here to stay in Bear Lake.”

Related: Bear Lake Watch working to control invasive species in the lake