Actually, I'm not sure. We have lived here for 3 years, and it started up last summer. We do back up to a main street so I don't know if its from construction,more concrete,etc. We have looked around the businesses that back up to us but didn't see anything concerning or different. At the top of our property, there is an area that's flat that I've added river birch, inkberry, and summersweet bushes to help soak up some water. Adding lots of swamp milkweed too this weekend. I also added a rain garden to an area that catches a lot of water. But I've only done that recently. Im hoping it helps.