factors affecting water clarity MN

[DetectorGuy]

Now I don't want to implicate the farmers as my dad was one and I kinda have a hobby farm. I think poor clarity relates directly to the amount of fertilizer that was introduced to that body of water. Even citiots (sound it out...) have enough common sense to have the phrase "this runs to the the river" on their catch basins and manholes. I always figured farmers to be a good bit smarter than city folk but they missed the big picture for years when they continued to fertilize fields on the side of a hill where the fertilizer eventually runs into the creek at the bottom of the hill. This creek runs into the lake and the lake plants grow like mad. Even microscopic algae likes to eat this fertilizer and this is what we see in front of our masks when we get to the surface and tell our buddy "visibility sucks here, Why did you want to come here today?"

Now there are more farmers in the Southern and central Minnesota than in the North. I think you will find better water clarity where farmers aren't... This has the most to do with clarity in my humble opinion. the second thing that would affect clarity would be soil consistency that the body of water sits on. Third would be that amount of movement of that water (both natural movement and man-made movement). Fourth thing would be the amount of oxygen in the water that algae needs to grow. More algae = more oxygen produced by that algae (see the vicious circle forming here?) Fifth would be the season for that algae to grow (this would go hand-in-hand with water temperature.) The greener the lake is, the more the surface acts like a solar collector warming it up and accelerating growth.  The last thing that would affect clarity would be the source of that water directly. This would be a series of muddy tributary rivers or a series of subsurface springs.

Even though I haven't tried Ice Diving yet, I agree with Shooter that the best clarity in any spot would be under a sheet of ice. So this winter I hope to tag along with Shooter, A&A, and Arcflash on many of there ice dives...

[freedivernd]

farmers.. shoot man, I thought it was from lake property owners fertilizing their lawns  .  Nutrients feed organics. and organics affect the vis.  One spot that I dive is just thick with overhanging trees.. and the bottom of the lake there drops to about 40' real fast.. and the bottom there is covered with silt and decaying leaves.  Someone should get a big vacuum cleaner to go along and suck about 3' of muck off the bottom of some of these lakes.. maybe there's some good clay, sand, or gravel down there.  I think there is grant money potential here..

[DetectorGuy]

How much older do you think these Southern lakes are than the Northern ones?... 5 minutes older? The glacial melt that happened many, many years ago happened on a large scale and basically at the same time. When you look at the pre-historic time line of the geology of Minnesota, this was all just a blink of the eye. I would be interested to know the bar-tenders name who was your "reliable source".

[DiverQueen]

Yes, Southern MN does have more farms, I grew up in that area.  One lake where we used to swim when I was a mere polliwog had NO VIS.  I was in there snorkeling two years ago and you could actually see bottom at 3+ feet.  What else has changed??  The have installed septic systems and upgraded old ones!  (Please don't tell me what I was swimming in!  : )

I thought algae was anaerobic (That's what my brother used to tell me anyway).  Add oxygen to the water and it reduces the algae bloom?!?!  Well, it didn't work in the pool either.  Where can we get 10 million gallons of "Pool Algaecide?"

         ;D Mmmm, nice warm pea-green lakes!!!!  ;D

Just kidding!  I need another trip to Crosby or Superior real soon!

[Shooter]

Looking forward to it  8)  We have added some equipment! Can you say "give me some slack tender"  ???

[DetectorGuy]

Looking forward to it  8)  We have added some equipment! Can you say \"give me some slack tender\"  ???

Up until I went with you guys and watched you Ice dive last year, my goal was to learn as much as I can to improve the experience of these short dive seasons. Since then my goal has been to get the right equipment to not only extend the diving season, but to make it a perpetual dive season. I think I'm set now and I can't wait till the water gets stiff... When I'm tending the rope this year I will give you more slack. ;D

[popolarbear]

grant money is hard to come by these days.... but i agree. several of the city lakes have monsterous weed machines that cost millions and are suposed to increase water quality. they have this backwards.. compleately. i met a guy at the U doing research on PHospherous nutrient cycles in lakes. they were trying to increase a lakes productivity by understanding how phosphorous gets used in by the lake. those crystal clear lakes have no phosphorous. if you could majicaly remove the phosphorous out of the nutrient cycle of the lake... it would crystalize the water clarity.....and vis versa. some of those lakes that as a child everyone localy knew as crystal clear lakes are slowly becoming stagnant and green. lake calhoun as a result of removing direct drainage of storm sewers into that lake,.. is becoming much clearer. two weeks ago on one side it was still only 4ft vis. but i am under the impression that some parts of this lake are becoming dramitiacaly improved in water quality. esspecialy if you look at filiment alagae which is also a sign of pooor over nutrient rich water... on the north side of the lake these algaes are gone. still some present on  the south side. ..with some additional water improvements this lake will likely be the clearest lake in the metro.


"phosphorous cycle" is probably more important to the green water problem than any other single factor. in japan and the orrient. fish farmers regulary "walk" the bottom of their ponds to release phosphorus from the mud layer. the water will bloom with planktonic algae, then other types of dyphania. finaly larger aquatic predators will increase in numbers. the result is a larger yield of fish per acer...

if the mud layer were to be removed.possibly used as an organic farm fertilizer. the lake water quality would become unreal. milfoil would also be reduced as it doesnt do well in hard bottom.

some of our lakes also occasionaly become nutrient limited by c02 levels but that is less common. you will see platlets of calcium deposits on the surface of plants and algae that are starved for co2 and remove it from the minnerals of the water forming something called bio-genic decalcification.(my spellings bad. sorry)..

any ways interstings.somebody needs to invent a muck sucker!

[DetectorGuy]

What I'm going to say kinda relates to the silt being "nutrient" rich... I just finished a large construction job in Elk River. The building site was about two feet of "silt" that had been dredged from a lake near the Sherburne County Police Dept. This silt was sitting on top of 26' of glacial till. Then the water table and what ever below that. We were going to scrape off this silt/topsoil and re-use it after the project was done prior to landscaping. We had Braun Testing test the topsoil and it was found to be void of any nutrients at all. It was heavy black dirt but it was completely sterile. We used a huge amount of fertilizer and a high volume sprinkler system to get the sod to grow. The landscaper said he could grow grass on asphalt if you add enough fertilizer. So I don't know if all silt is sterile or not, but this stuff sure was. The weeds as you all know stop where the sunlight can no longer reach the bottom. Deeper than that there is usually nothing but silt. ( I am speaking in generalities here and I realize that there are some exceptions) In the shallower areas there are more weeds but less silt. In the deeper areas there are less weeds and more silt. Just my imagination?... Kinda makes you go: Hmmmmm?

[popolarbear]

ok,this would be also an odd comment but interesting. i once was camping on the river at a location were we had camped(and others) so many times that there just was not enough logs to burn. i found one large one that after some pulling we pulled out of the hill side. it was strangely dry enough to burn along with several other that we scavanged. after all night of burning it was still partialy left over. it had a weird coloration to the remianing ashlike burnt reminant. and what was left was hard like iron. i was woundering if this piece i pulled out of the bank was perhaps partialy replaced by underground mineralization..or partialy fossilized??? im sure that bank was there for hundreds of years..

[Shooter]

the new equip with com gear