Hello Mary!
Although it's a few days since your posting of this question, I figured you may still be wondering the answer. Those "settling ponds" are usually the area the township has dictated during the planning process that must be used for storm water management and run off. Having said that, in some areas these locations will eventually fill in from the bottom where there are higher than average water tables and it will likely resemble a pond. In other areas, the area will simply resemble a field with possibly a drain present and may never hold water again. As far as the idea of any stench from sitting water it's unlikley since the whole reason is for water to move through there, although the best way to answer this is to ask!

If it's an established neighborhood then ask the neighbors. I always tell my buyers to interview the neighbors in a developement they are considering making an offer anyway. If it's new construction, then an experienced agent will look into issues like this and many others you wouldn't think to ask about unless you bought several homes a year. But likely the answer would be no, there aren't typically many complaints about odors nearby. At least not that I have ever heard in 17 years of practice!

Irene Butler
Partner / Realtor
Keller Williams RE
276 B Dilworthtown Rd
West Chester, PA 19382
610-399-5100
Cell 484-576-9491
IreneButler@kw.com http://www.IreneButler.com