Abandonment of Common Areas

Recently our builder turned over the HOA to the homeowners. As part of that was the ownership of several ponds and detention/retention areas. Now the ponds drain into the local streams and rivers, thus come under water quality standards for our state. But the water and the pond bottom have never been check for contamination or debris that might leach. We (the homeowners) know that construction debris and materials (tar, concrete, paint and other pollutants) was dumped into the ponds. Since we now own these potential liabilities, the board is thinking we may have to spend a boat load of cash on cleanup, fines and such, that would bankrupt our HOA easily. Any suggestions for how to protect the HOA or recourse we should follow to hold the builder responsible?

Jim