Have you ever seen a total weed kill on a private ski lake?

[ski4xtc]

We have had a total weed kill in one of our lakes and I am trying to figure out what has happened. We have two lakes that are not connected that are both stocked with grass carp. We have coontail weeds which the grass carp do not eat very well. We also have cooler water and only reach 80 degrees for a short time in the summer. Right now we are in the low to mid 70’s. For the last five years our fish have maintained the weeds but we still have had a thick two foot blanket on the bottom.

This year our north/south lake had the usual two foot blanket of weeds. When we worked on the course in May, it was hard to find the anchors due to the weeds. In early July, the weeds disappeared – almost overnight. The lake has been a diarrhea brown color since and does not appear to be from sediment on the bottom. We have always had clear water and this water does not clear up even over night after settling. The color is in patches too.

 

One other factor is we spot spray the shorelines with just glyphosate and 2-4-D. I did not start spraying the shoreline until late June and we have had very little rain since. The spaying on the lake with the weed kill has been very minimal. I am pretty sure it is not the cause but do not want to leave any possible factors out.

 

Our water supply comes from deep wells. One deep well goes into both lakes and the other one goes just into the lake with the where the weed kill has happened. We have a shallow well that is close to our septic tank. That water was tested last year and it was not too far out of the norm. Also, the septic tank was pumped in 2013.

 

The only time I have ever seen a weed kill like this is when a few beers were consumed and four times the chemicals were used that were supposed to be put in. This was about 10 years ago and we had a complete weed kill at that time. Right after that we had a good wind storm and the weeds were totally pulverized. After that the water was the same diarrhea brown for the rest of the year.

To my knowledge, no weed killer has been used this year. Have you ever seen this before? It is a little alarming not to mention our grass carp do not have anything to eat. I have been bringing out my grass clipping from home which they come to the shore and eat immediately. I am guessing it is not enough for them to survive on.

 

Thanks in advance for your replies and input.

 

[Waternut]

Heavy rains and dirt run off causing dark tinted water which doesn't allow light down to the weeds? Just a guess but I've seen some pretty gross looking water last for a while after some really heavy rain. The large public lake I live on is poo brown all winter long from the rain.

[Wayne]

Have you had any water tests done on the wells feeding the lakes or the lakes themselves?

[bishop8950]

Interesting. Where are you located or better yet what lakes? It's great you have "control" lakes to compare. Wondering what the differences are between the lakes. Shape, depth, age, exposure, weather (assuming all the same but worth checking). The incoming water does sound like a possibility.

 

I doubt incidental shoreline herbicides would do that. If it did we would have a lot less lakes with weeds! As you probably know to force a whole lake weed kill you have to use a serious dose of herbicides.

 

If it's not the incoming water, I wonder what natural/biological contamination could have happened to cause this? Just the right water conditions, some birds bring something into the lake, something blooms....

 

I have been working on ski lake water quality for a few years so still learning. But one thing that keeps coming up is weird stuff can happen at any time. The living changing ecology of a ski lake can surprise us and be difficult to pin point, unfortunately.

 

Answering the question, I have not seen this before. I would start with water testing of the lake and incoming water.

[DaveD]

Is that downriver of Silverton, CO?

[Drago]

@daved do you really think that is funny?

[eleeski]

If you figure it out, let us know how to replicate the total weed kill!

 

On second thought, Sunten is right next to that chemical weapons place. Maybe I don't want that. ( @DaveD along those lines, I thought that was funny.)

 

Seriously, do you have quagga or some other plankton feeder? They can be susceptible to water changes, PH, chemicals, diseases and such can cause population crashes. If your plankton feeders die, the plankton will bloom and choke off the pond weed.

 

I remember Sunten as having clay brown water. Nice for keeping pond weed down. There are advantages to those big wakeboard boats stirring up the lake.

 

At least you have water.

 

Eric

[DaveD]

@drago, too soon?

[Drago]

@DaveD That's what I was thinking, too soon.Still at 500 gallons/minute and very nasty stuff. I know people there , and it goes into Lake Powell (although I heard it will be ok -- not hurt Powell. It's mostly deposits on the shorelines for quite a bit downstream that suck)