Control lake vegetation with drawdown?

[livemusic]

Does anyone know if you draw a lake down for a few months (over winter), will it kill hydrilla? A local lake is being overtaken by that stuff.

 

Related, I see where a local lake is beginning drawdown today and the wildlife dept. says... " the drawdown is intended to boost lake fertility, allow for bottom oxidation, and to control aquatic vegetation."

 

To boost lake fertility... ??? how does that work? Is it that some plant life will sprout and grow between now and late October (and that is good?), which is when they will put the plug back in?

 

To allow for bottom oxidation... what is that for? Allow it to breathe or help with the thermocline or what?

[WRB]

To kill the decayed vegetation so it doesn’t use up dissolved oxygen (DO) when covered with water. Sunlight and air dries out the wet decaying junk oxidizing in the process, like compose.

Tom 

[casts_by_fly]

Tom explained bottom oxidation.

 

Drawdowns work to greater or lesser extent depending on the specific aquatic weed, the length of drawdown, and the conditions during drawdown.  For instance, if you freeze most aquatic vegetation seeds they will die.  That means extremely cold temps or just very cold temps for a long time, enough to freeze the lake bed down to the seed level.  We have a lake here that was about 20' low over the winter when we had the 0F conditions around christmas for a week plus.  There is no aquatic vegetation in the lake this year.  None.  Other lakes in the area draw down 4-8' over the winter to knock down some of the weeds rather than use chemicals.  It works somewhat for us (primarily milfoil and pondweed), but there is still more weed in the areas not drawn down and it only takes the spring for it to spread again back into the shallows.  

 

Lake fertility just means that the oxygen can go to better uses than breaking down the junk on the bottom.  

[Team9nine]

Drawdowns are usually not very effective against hydrilla, especially if it is already well established in the lake. Your location that far south also wouldn't help much due to a lack of freezing temperatures for any length of time, and studies show desiccation of tubers (drawdown, dry out) isn't a great option for control.

[Catt]

One of the reasons Toledo Bend lost all of the grass was a extremely low lake level followed by a historic high lake level. 

[Bankbeater]

I don't know about hydrilla, but it wiped out the lilypads in one of the small lakes I fish in.