Even among those who live in the Great Lakes State, there is a lot of confusion about the health of the Great Lakes.

Some believe that because the lakes are clearer than ever, they’re more healthy, when in fact that clarity is due to invasive species killing off the bottom of the food chain.

Dan Egan knows all about challenges facing the Great Lakes, and his recent book, The Death and Life of the Great Lakes, chronicles the history and ecological changes of the lakes.

Egan sat down with Stateside’s Lester Graham to discuss what is threatening the Great Lakes, and how historic acts change the lakes we know today.

Listen to the interview above, or read highlights from the conversation below:

On how the Great Lakes have changed greatly in a very short time

“Despite their vastness, [the Great Lakes] span collectively some 94,000 square miles, but they have, until relatively recently, been as isolated as a pond up in the north woods. And that changed with the construction of the canals that linked the lakes to the Atlantic Ocean. And by those canals, I mean first there was the Erie Canal and then the Canadians built the Welland Canal, and that process culminated with the opening of the St. Lawrence Seaway in 1959, which allowed for the very first time, some really big boats to come into the Lakes from all over the world.”

“The problem is that these boats didn’t just bring the cargos that were listed on their manifests. They brought a lot of unwanted cargo. And by that, I mean specifically invasive species. These are organisms that really hitchhiked their way into the Lakes in overseas freighters’ ballast tanks.”

On the effect of sea lampreys

“The first lampreys were discovered above Niagara Falls sometime -- I’m going from memory here -- but I think it was in the 1920s, and it did not take them long to totally devastate the Great Lakes’ premiere predator, which was the lake trout.”

“And the lake trout was kind of like the wolf in the system; they controlled the flow of energy, they kept all the smaller species in check. And when the lampreys took them out, that opened the door for smaller fish to explode.”

On how sea lampreys and alewives led to the introduction of salmon

“They poisoned the streams and tributaries in which the lampreys were spawning, and that knocked down their numbers to just a sliver of what they had been, and that opened the door to the restoration of a top predator in the Lakes. And somebody could argue that the natural answer would have been lake trout, remnant populations of which were hanging on in Lake Superior and other areas of the Great Lakes.”

“But the state of Michigan decided to go in another direction. They saw these alewives as a potential boon for a salmon fishery. So the state acted largely unilaterally back in the mid- and late-1960s to bring in Pacific Coho and Chinook salmon, and they planted them in the Lakes.”

“So it’s really kind of a strange situation if you think about this. You’ve got this Atlantic invader being feasted upon by a Pacific predator in the middle of the continent, in a place that isn’t an ocean. And it was a program that worked magnificently to create what is today a multi-billion dollar sport fishery.”

“Zebra and quagga mussels have invaded significantly or severely in Lake Erie. And these things suck plankton, suck anything floating, out of the water. And they’ll eat just about anything. They don’t have brains, but they’re smart enough not to eat a certain type of cyanobacteria called microcystic. You can see it in YouTube videos, where in an aquarium, a mussel will be sucking all these flecks out of the water, and for some reason just spits one back. Well, that one is this form of toxic algae. So when you have an algae outbreak, it’s much more likely to be this toxic stuff than a whole assemblage of different types of organisms that would have been the case back in the 1960s.”

On fixing the problems in the Great Lakes

“We’ve come a long ways since June of 1969, when the Cuyahoga River last burst into flames. That river had burned a lot in the decades prior and so had rivers across the Great Lakes basin -- and the country, for that matter. Something about that fire that made people say, ‘Enough’s enough.’ And out of that fire, we got the Clean Water Act and we got dramatic water quality improvement. I don’t know what it’s gonna take today for people to say, ‘Enough is enough.’”