HUGE gnat problem in yard! Any suggestions?

This year, we have noticed probably thousands of gnats lingering on the outer edge of our property. This is a first. We have never had them before, and not sure what could be causing them. We just planted a vegetable garden, but nothing has actually produced fruit yet. But that is the area they are in (about 20ft from it). We live on the lake. Could that be why? I want a cheap, and natural as possible way to get rid of these things fast. Something without chemicals for the garden, kids, runoff into the lake, and pets. Any suggestions? Thanks in advance.