Pond Boss Forums INTRO Questions & Observations Need drawdown advice

We have a 10 acre lake in central NC with depths ranging from 1' in the shallow end to 13' at the dam. We lowered the pond a month ago about 50%. Unfortunately a heavy rain over two days has filled it back to capacity. It is difficult to maintain a steady level due to creeks flowing in and a smallish drain line.

Questions: Is all that new water added so quickly bad for our fish? Is it dangerous to our fish to lower the pond again and try to keep it down through February?

Thanks much for any advice!

What is the reasoning behind drawing it down for the winter?

We are trying to put some structure in, work on a pier, and hopefully knock some weeds back. We have an issue with a water willow type plant taking over our shoreline.

Thanks!

You say the pond is 10 acres. How big is it when you have lowered the water level by 50%? What will the average depth be?

I am not an expert, but I do not see that the pond rapidly filled from streams is an issue unless it created a really bad turbidity problem, brought in unwanted species or brought in some kind of chemical runoff from surrounding area.

Some of the pros will weigh in I hope with better inputs for you.

Edit: How heavily stocked is the BOW? Supplemental feeding? Aeration?

I don't know if lowering it will reduce the weeds long term, but it will make working on things a lot easier.

Providing the following 2 things don't happen, you shouldn't have any problems with it regarding the fish in it.

1) High influx of water that is drastically different in *chemical* make-up than the existing pond water. I'm talking about having a large pH swing or the influx water being over 10 degrees different than the pond water if the water inflow will make up 50% or more of the pond water.

2) The pond freezes over for a week+ and it has snow cover on it if you don't have an aeration system in the pond. That will limit the sunlight getting thru the ice which allows the phytoplankton to make O2.

Barring those two scenarios, I think you should be O.K.

Now, drawing it down will concentrate all the fish into the smaller amount of water, and there most likely isn't a lot of cover for the smaller fish to hide in. So, the predator fish will have an easier time getting breakfast, lunch and dinner.

I don't think there is any worry on the heavy water influx. The runoff is all from the same, original water shed, so there should not be any pH or other water quality differences....Further, the lowered lake will re-fill over hours, not minutes, so the fish will easily temper as the fresh water enters. In fact, due to the concentrated bio-mass of fish, I would bet the influx reduced some rising ammonia and nitrite levels...the fish most likely benefited with the fresh water.

Also, even if there is a big temp difference from the lake and runoff, the waters will not mix instantly, leaving many safe pockets for temperature acclimation (15-30 minutes) to occur.

My biggest concern is what esshup mentioned about the concentration of fish. If this is a mature lake and lowered, depending on what is being related as "about 50%", the lowering itself could put the fish at a big risk, from predation and rapidly deteriorating water quality.

If lowered 6' (50% of deepest point), depending on bottom slope there could be 80+% of the lake's total water volume removed.

Thanks so much for your help! We are probably going to test the water soon and if it's good, leave it full for the year. Our pond management company says we can spray the weeds effectively in the Spring.

If the drawdown lasted 2 weeks then you should have achieved a significant benefit.

Thanks so much for the advice. Our lake has been full for 8 days and the water is at normal levels and is clearing up nicely despite more rain. We are about to get a significant blast of cold air for several days with highs in the 20s.

Would taking the level back down 3-4 feet help eradicate any weeds? We have a water willow and some filamentous algae an we're hoping the cold would help us.

I am hesitant to change the water level though.

Thanks!

Does the water coming into the lake have less nutrients in it than the lake water? If so, then drawing it down will help with the FA problem by reducing the amounts of nutrients availale for it to utilize.