If you fish, you likely consider it a cherished pastime. If you don't fish, it still impacts your life, as the sport generates $4.7 billion annually and the number one tourist attraction in the state.

Either way, scientists say Minnesota’s lakes are changing forever.

According to a report Minnesota Waters—a group that monitors lakes across the state—the state isn’t doing nearly enough to prevent the infestation of zebra muscles.

Four years ago, tiny invaders began creating big changes to Mille Lacs Lake and everything in it.

"In 2005, we found a zebra muscle scuba diving, just by accident, dumb luck," said Department of Natural Resources Large Lake Specialist Tom Jones.

DNR crews searched the lake for weeks and only found more three more—a total of four zebra muscles in 2005.

But in 2006, officials found eight more. In 2007, they found 131 and just last year, they found 24,000—that’s less than one zebra muscle per square foot.

With the lake spanning more than 128,000-acres, one might think it's too big to be harmed by something so small as zebra muscles.

"It can change the whole eco-system," Jones explained. "One zebra muscle is nothing. The problem is there can be thousands and thousands and thousands of them."

This year, DNR officials are predicting there are 100 to 200 zebra muscles per square foot in Mille Lacs Lake. It’s inevitable that they will spread too—the only question is how far and how fast.

"Any lake they get into…they're going to become so abundant that the water clarity will increase, if it's a walleye lake, walleye fishing will become worse in the daytime," Jones said.

Zebra muscles feed by filtering—they're so terribly efficient, the water clarity improves dramatically.

"With the clarity improved, the walleyes sensitive eyes don't like all that extra sunlight,"

Experts say that extra sunlight will drive the walleyes into the shadows and weeds, making them harder to catch.

Zebra muscles have only been in the U.S. for 20 years. Experts say that once they establish in a lake, its fate is sealed.

"It’s too late to stop whatever is going to happen," said Jones.

Because there is no cure, the state says they’re going to focus is on prevention—preventing what most DNR officials say is untimely inevitable. While most won’t argue that zebra muscles won’t spread, it’s now about slowing it down.

Currently, the state is spending $100,000 a year on protection grants, but that averages out to less than $10 a lake.