The July 31st and May 29th issues of Science had some updates on the restoration of the Chesapeake bay. This bay teemed with an incredible diversity and abundance of life when Europeans discovered it. It's since been largely destroyed by agricultural and industrial pollution.
It sounds like they may be making some progress at least. Oysters previously formed extensive reefs that filtered the water and supported much of the ecosystem. These reefs previously existed as giant piles of empty shells that oyster larvae would settle (and eventually die) on, leaving their shells behind. A research project has been able to establish a few new reefs by dumping huge numbers of oyster shells into piles at the mouths of rivers. One of the key discoveries was that these piles had to be very high to prevent being covered by mud.
Hopefully this strategy will continue to work as they try it around the bay.