Something is wrong with Lake Itasca, the source of the Mississippi River

[NickB79]

https://www.kaxe.org/local-news/2025-10-02/something-is-wrong-with-lake-itasca-the-source-of-the-mississippi-river

The water clarity in Lake Itasca has been steadily declining for years. Nutrients that can feed harmful algae blooms and turn the water a sickly green are unusually high for a lake of its size and pristine location.

Minnesotans have done everything they can to protect this picturesque lake in an ancient woods from which the country’s great river begins. But Lake Itasca’s chemistry, shallow depth and even its unusual wishbone shape may make it particularly vulnerable. With higher temperatures in northern Minnesota allowing less ice, the lake is receiving more sunlight and a longer growing season.

[John1956PA]

1. Why don't they just follow Trump's train of reasoning and nuke the lake?

[2naSalit]

3. Or sweep the forest.

[Mblaze]

7. The not so funny thing is

That half of the forest land in California is owned by the federal government. I don't see Trump sweeping those forests.

[viva la]

2. How does that huge river start here?

Foolishly I assumed its headwaters were Lake Superior.

[Mister Ed]

4. Lake Superior's waters flow toward the Atlantic through the other Great Lakes and then the St. Lawrence River.

The water would have to flow uphill from Lake Superior in order to reach the Mississippi watershed.

That Mississippi watershed is of course fan-shaped and not linear. It's made up of countless tributaries, large and small. Although I don't know for sure, I think that the way it's determined which stream is a tributary and which is the main channel at any given juncture is to estimate the volume of water that flows in each. The stream with the greater volume is declared the main river.

Working upstream from the mouth of the Mississippi, and dividing main channel from tributaries in that manner, one comes eventually to Lake Itasca, which is declared the "source".

At least, that's how I think it works. But I'm not entirely certain.

[John1956PA]

5. Yes, the tracing rivers upstream can be interesting.

For example, I believe the Ohio River is mightier than the Mississippi River at the confluence of those two rivers.

[Mister Ed]

6. Ah! Then maybe it's just a more or less an arbitrary decision on the part of mapmakers.

The Missouri is certainly a longer stream than what we call the Mississippi. I've long wondered if for that reason the Missouri should be called the main river, and not a tributary.

[John1956PA]

9. I think the historic names of the rivers are always honored.

I think the "Mississippi River" was always regarded as the name of that particular waterway which runs from the northern tier of our country south to the gulf. Yes, based on volume of water at the points where the Missouri River and Ohio River meet the Mississippi River, the distinction between "mainline" and "tributary" is not clear in my mind. However, I will say this. I think I misused the word "confluence" in my previous post. There is a true confluence between the Allegheny River and the Monongahela River in Pittsburgh. One river comes from the north, and the other from the south. They form a point at which neither one looks to be feeding into the other. The two rivers just simply come together. On the other hand, the merging points of the Missouri/Mississippi Revers and the Ohio/Mississippi Rivers have a different cartological look than the confluence at Pittsburgh. Since the Mississippi River is the central receiver in the watershed which bears its name, I can see where it is considered the mainline, rather than a tributary to the Missouri River and the Ohio River.

[lastlib]

15. But it all flows......

to the Gulf of **Mexico**, right?

[Beartracks]

17. Well SOME names aren't always honored by SOME people.

============

[BaronChocula]

10. The different criteria for measuring rivers gets things convoluted

Length vs. drainage basin vs. discharge. Can't they all get along?

[erronis]

8. In addition to some other good explanations, there is the matter of old names established before known characteristics.

Knowing the volume or length of a river 200+ years ago was an inexact science. Once a name is established it is very hard to change it.

I was taught that the Missouri River AND the Mississippi together made the longest flow. The Missouri flows into the Mississippi so perhaps the combined should be called something else.....

[GreenWave]

11. Just call them all America River or Trump river to get instant approval.

[NickB79]

20. It's a rite of passage for MN kids to walk across the headwaters

It's literally a shallow stream with enough exposed rocks to act as a bridge. Our 6th grade field trip in 1989 was up to Itasca. Somewhere there's a picture of me and the other 30 kids in my grade holding hands across it.

My daughter will be going next spring to do the same.

[Lulu KC]

12. My heart hurts

Childhood memories and souvenirs.

[Botany]

13. One of the problems might be non native bivalves... shell fish such as mussels .. that causes phosphorus to

become a bigger component of the lakes’ ecosystems and that P feeds the algae which in time
causes algae blooms that then cause O2 deprivation in the water and the system crashes from
there. I don’t know if that is the case in Lake Itasca but it is the case in the western basin of Lake
Erie.

Another problem is that we are killing the earth with fossil fuels too.

[Wounded Bear]

16. Seems unlikely. Erie gets ocean going vessels from the Atlantic...

Lake Itasca doesn't. The mussels in the Great Lakes are imported.

[Botany]

18. All it takes is one boat that was in the Great Lakes and not cleaned off underneath and or a shore or

wading bird that picked up some of the non native bivalve eggs on its legs and then it goes
to an inland lake and the problem is spread.

[NickB79]

19. Zebra mussels haven't been found in Itasca. Yet

But they are a huge issue here in Minnesota, infesting most large lakes now.

[Botany]

21. I am a half of a bottle of wine into my evening but this is a different creature from zebra mussels.

You can do your due diligence about keeping fertilizers out of a watershed but you can
still see the damage from non native bivalve offsprings.

[FakeNoose]

14. I remember reading many years ago, that the creeks and streams of lower Ontario

... feed the lakes of upper Minnesota, including Lake Itaska.

Is that true? It seems like there's water everywhere in northern Minnesota, including many marshes and swamps. I don't know how geologists and map-makers can determine that the Mississippi River goes no farther north than Lake Itaska. It doesn't seem credible.

On the other hand, mining runoff can destroy freshwater lakes and rivers anywhere. I live in Pennsylvania where pollution from old mines has ruined much of our natural aquifer.