Pond Boss
Posted By: esshup OK, here's a tough question. - 12/10/19 06:09 PM
In an eutrophic lake, say there is an area that is 2 acres covered with Spatterdock and is 2'-3' deep due to sediment/muck that has accumulated over the years. If that area of sediment/muck AND Spatterdock is removed, how many submerged plants (area wise) are needed in the lake to replicate the nutrient reduction/utilization of the existing Spatterdock?

WAGS aren't valid ( I can WAG with the best of them, even SWAG), please attach links to supportive material or studies.
Posted By: teehjaeh57 Re: OK, here's a tough question. - 12/10/19 10:51 PM
5
Posted By: Snipe Re: OK, here's a tough question. - 12/11/19 01:16 AM
The sediment/muck is a big part of the nutrient source (thinking out loud) if you increase the depth to a point any useful vegetation will not grow then I would say you will never duplicate/replicate nutrient use by plants.
I would have to go back to the 20-25% rule. (of the newly opened up area)
I'm also on board with TJ's "5"..
However, should we also have a handle on what plant species is best at converting nutrients as well? This would change the amount, or % needed to replicate Spatterdock, would it not?
Also..if removing nutrient load in muck/sediment, will it REQUIRE the same conversion rate?.?….
Posted By: esshup Re: OK, here's a tough question. - 12/11/19 01:27 AM
Originally Posted By: Snipe
The sediment/muck is a big part of the nutrient source (thinking out loud) if you increase the depth to a point any useful vegetation will not grow then I would say you will never duplicate/replicate nutrient use by plants.
I would have to go back to the 20-25% rule. (of the newly opened up area)
I'm also on board with TJ's "5"..
However, should we also have a handle on what plant species is best at converting nutrients as well? This would change the amount, or % needed to replicate Spatterdock, would it not?
Also..if removing nutrient load in muck/sediment, will it REQUIRE the same conversion rate?.?….


Yes it would require the plants. What I didn't say is that this is in a 365 surface acre lake that is starting to experience Cyanobacteria blooms in late summer. There is going to be a nutrient reduction plan put in place, a bottom diffuser aeration plan, and a dredging plan also put in place. This will be a long tedious process, as the homeowners (i.e. boaters) want minimal underwater weeds, at least not within a few feet of the surface and minimal weeds along shore in front of the houses. The last time the sediment build up was measured was in 1999, and at that time it was estimated that in the existing 2' to 7' water depth range there was in excess of 195,000 cubic yards. (Personally I think that is WAY under estimated given the 75 year old bathyspheric map that I have.)

This area in particular is out in front of where a ditch enters the lake.
Posted By: Snipe Re: OK, here's a tough question. - 12/11/19 01:47 AM
esshup, I believe there are changes occurring with Cyanobacteria or strain of. We have had serious issues with this in the western KS impoundments in the last 4-5 years that never had experienced this prior in the older reservoirs. I don't know what's changed but we do have documented ave water temps for 4 yrs on 2 of these locations and the ave is not going up on temp.
Interesting..
Posted By: Bill Cody Re: OK, here's a tough question. - 12/11/19 01:57 AM
Your "tough" question needs a specialist in botany, preferably an aquatic macrophyte specialist - likely a botany professor. There should be some sort of research study that determines the nutrient consumption by spadderdock. I find it hard to believe that a journal article does not exist for this topic. I would start by locating an experienced aquatic macrophyte botanist or biologist.
Posted By: ewest Re: OK, here's a tough question. - 12/11/19 04:31 PM
I have not seen anything like that type of study in the Fisheries area. Probably in the Botany area journals. I don't think you will find an answer on topic and point as to your lake.

You will have to extrapolate from scientific info as it applies to your facts. Likely a fly by the seat of the pants approach is in store.

Good luck and please let us know what you find.
Posted By: esshup Re: OK, here's a tough question. - 12/13/19 04:29 AM
Thanks guys! This will be a difficult project, basically because it's "govern by committee". Plus it's a public BOW, so there are permits to apply for, etc., etc.
Posted By: RAH Re: OK, here's a tough question. - 12/13/19 11:37 AM
Perhaps get help and buy-in from DNR or Fish and Wildlife to help "grease the wheels"?
Posted By: esshup Re: OK, here's a tough question. - 12/14/19 04:11 AM
Working on that. Have to have a sediment survey done first, last one was done 20 years ago. There is a cost share plan of 80/20 once the plan is approved. The state/gov is the 80% part.
Posted By: RAH Re: OK, here's a tough question. - 12/14/19 02:44 PM
Nice when you can get financial help on projects!
Posted By: ewest Re: OK, here's a tough question. - 12/15/19 12:52 PM
Please post info as you proceed. There will be a lot to learn from this that applies to many pond restoration projects.
Posted By: esshup Re: OK, here's a tough question. - 12/15/19 08:12 PM
Will do ewest. So far the budget for next year is in the $200,000 range, but that's without any matching funds. This lake has 3 streams/ditches entering it. One had settlement ponds installed on it but they haven't been cleaned out in 20+ years so they are pretty much non-functional now.

The lake is over 150 years old, and when the State Highway Dept renovated the dam and highway in 2009, they also changed the bottom drain discharge to a spillway system. Since 1955 the lake has lost 21% of it's water volume to sediment accumulation, with the most rapid change occurring after the dam was renovated.

Aside from getting funds and approval for a large scale dredging effort, I don't see the eutrophication process getting turned around. There IS land available to put the dredged material on and the land owners have given their permission.
Posted By: ewest Re: OK, here's a tough question. - 12/16/19 06:56 PM
Sounds like poor planning on the State Highway Dept. They should have at least added a bottom drain aspect to the spillway design.
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