Our pond was sprayed with Sonar last Wednesday. I note on the label that it is to be used in a body of water with no or very low water flow. Last Monday we had a major storm that lasted for hours. The rain was extremely heavy, and since the ground is already saturated it went as run off. We had floods all over.

The 6 inch discharge pipe on our .4 acre pond would have been running at near full capacity. Since the water was already near the top of that inlet it would have started running very quickly. It is still running now. What can be expected with the Sonar concentration?

Garryc...did you do the application or did you have someone do it? What plant were you treating for and at what rate or concentration was the sonar applied? You can look at SePros website and you can order a FAStest (i am unaware if any other company/lab offers this test) which will tell you how much fluorodine is remaining in the pond. At that point you can consult with SePro or your applicator on how to proceed. Besides dilution from the rain Sonar will degrade a little every day so if you do go with the water test I would think about grabbing a sample soon after the rain and keep it in the dark and ship it off as soon as possible.

IMO the Sonar conc will decrease to levels way below what was originally applied. You will likely have to retreat with at least 50%70% of what was originally applied. A heavy inflow & outflow of water can create a significant dilution of the chemical. About 30% to 60%+ of a pond's water is in the top 3ft. Percentage is dependent on the average depth.

Well, I was wrong. I was told it was Sonar, but when I looked it was clipper. Am I to understand that if you mix CUTRlNE-PLUS with Clipper it weakens the cell walls and makes the clipper more effective?

Also, I'm told that the expert said that all the trees in the water are not a problem, nor is the mass of leaves that fall in it from them. They tell me that she said she would sell us a Bio-Digesting product for that.

I have a bit of a problem taking advise from someone who's only interest is in selling you products and services. That does not matter what degree they have, sales pay the bills so sales take top slot.

are they just using clipper for algae or what plant are they trying to kill?

What was/were the target-pest(s) for which the treatment was applied?

Watermeal and duckweed

CLIPPER was an appropriate treatment, especially if the pond is prone to significant flow-through events.
Not sure if the CUTRINE was necessary; I suppose it's possible, assuming algae was present or anticipated.
CLIPPER will generally do a fantastic job on both duckweed, watermeal and several other species - but, has a very limited duration of herbicidal activity. Then again, not even fluridone (SONAR, etc) could provide residual activity in a pond with transient water-flows.
Assuming the CLIPPER treatment remained isolated in the pond for 24-48 hrs following the treatment, I would expect excellent results on the "existing populations" of duckweed and watermeal. However, weed-rebound from germinating seeds (unaffected by the treatment) should be anticipated in the future.
I'm guessing the transient-flow of water during the recent rain-event was insufficient to "flush" much of the duckweed and watermeal down the creek. Yes?

If previous nutrient conditions (eutrophy) remains the same in the pond, expect the watermeal and duckweed to return because the causative agents are still present.

That goes back to those dang trees Bill. Dumping lots of leave in every fall and mostly rotting after flow has stopped. If they were cut down then cattails would grow in the cove they are in, which is our inflow, and filter a good deal of the phosphorus out. But cattails and pickerelweed do not grow in heavy shade.

So we have to harvest them a few times, how many times a summer I don't know. Does anyone else.