That's odd that you'd get complaints of poop at that distance. I live within the city limits of Seattle and have 4 of my 11 hives plus to recent swarm captures on my carport roof (above a structural wall). I notice a few poop spots on my truck that's parked 30 ft away, but haven't had any complaints from neighbors and there are over 40 residences within a 500 ft radius of my property.
Is there some food source that's drawing them across these properties? Is the lake their closest source of water? If water is the issues, maybe you can alleviate the problem by providing an alternate source. Commercial beeks used to put hives on my families timber property and the shores of the closest ponds would be thick with bees. Take a trip you your neighbors and find out.
It sound like you live next to Lake Whatcom. I have no personal data on how far bees will fly over water, but check out this experiment
Distance Estimation by Foraging Honeybees looking at Optical Flow distance determination:
http://jeb.biologists.org/cgi/reprint/199/1/155.pdf. In it they summarize old experiments, one in which bees were going to a feeder 360 meters away across a lake. But, for the sake of argument, let's assume you live in that wide spot of Whatcom Lake just uplake from Sudden Valley. That 1 mile plus wide section is about 1,640 meters wide. It's about 4 miles NW and 5.5 miles SE straightline to get to either end of the lake before bees from your hive would turn the corner and start shortening the distance traveled (bee-lining). From what I've read, that 4 to 5 miles is about the limit of a bees range, but if some of those foragers got to the other side and liked what they saw, it might be possible if they started cutting the corners.
~Reid
