therine t. macarthur foundati.d unn bank. >> union ba has put its finaial strength to work for a wide range of companies from small businesses to major corporations. what can we for you? >> i'm julia stiles. >> i'm ken bacon. >> i'm kim cattra. >> hi, i'm ken burns. >> i'lili taylor. >> i'm nry louis gates, jr. anpublic broadcasting is my source f news about the world. >> for ielligent conversation. >> for ection coverage you can count . >> for conveations beyond the sound bites. >> a commitment to journalism. >> for deciding who to vo for. >> i'm kerry shington, and public broadcasting is my urce for intelligent connections to my community. >> "bbc world news" was presented by kt, los angeles. presented by kt, los angeles.

therine t. macarthur foundati. committed to buiing a more just, rdant and peaceful world. and ditional funding for frontline and for "poisoned waters" from the par foundation committed toaising public awareness. major fundinfor "poisoned waters" was provided by the seattle foundation. ur gift, your community. e russell family foundation. the wallace netic foundation. the morris and gwendyn cafertz foundation. the key campbell foundion for the environmt. the merrill faly foundation. with additionafunding from: thabell foundation the bullitt undation the rauch foundaon. and by t following: a comple list is available from pbs. >> narrator: puget und. chesapeake bay. they aremerica's great coastal estuars and they are ineril. >> i would put pug sound in the intensive care uni the situation is ctical. >> the chesapeake bay is lik the canary in the al mine. is an indicator of what we e now learning to expect in any body owater across the planet. >> narrator: the decades after the clean water act, frontline kes a hard look at why erica has failed for so long to cleanp the nation'