Stream Irrigation – Causes Weeds

Q: I suspect that irrigating from a stream has another negative aspect beyond the questionable cost effectiveness. I “inherited” a lawn which had been watered with stream water for several years. You would not believe the number of various strange looking weeds which had developed in this lawn. I had to kill the entire lawn, and replant. Would you agree that many of these weeds may have been introduced through the stream irrigation?

A: I guess it’s possible, but since the intake for the pump is near the bottom of the stream and since seed usually float, I wouldn’t think it to be likely.