EVOS and the Prince William Sound Long Term Environmental Monitoring Program

ABSTRACT Following the 1989 Exxon Valdez oil spill (EVOS), Prince William Sound Regional Citizens' Advisory Council began Long-Term Environmental Monitoring Program (LTEMP) in 1993 to track hydrocarbon chemistry of recovering sediments and mussel tissues along path (PWS) across Northern Gulf Alaska (NGOA) region. The program also samples sites near Alyeska Marine Terminal (AMT) within Port Valdez, primarily monitor tanker operations resulting treatment discharge oil-contaminated ballast water. Over last 28 years, has documented EVOS oil's disappearance at spill-impacted (albeit buried still exists a few unique sheltered locations PWS). Within Port, tanker- diesel-spill incidents have been over but all were minor with recovery times < 1 yr. Of highest concern permitted chronic release weathered from tankers' ballast-water that is treated discharged (AMT). In earlier years (1980s–90s), volumes reaching 17–18 MGD, up barrel finely dispersed would be released into fjord daily. two decades, total petrogenic inputs (TPAH43) declined as measured monitored mussels sediments. This trend reflects combination decreased North Slope (ANS) production thus, less traffic, plus transition double-hulled tankers segregated tanks, improved treatment-facility efficiency removing PAH. From 2018 collections, mussel-tissue concentrations eleven LTEMP stations (within well PWS NGOA regions) below method detection limits similar laboratory blanks (TPAH43 44 ng/g dry wt.). At these low background levels, elevated TPAH values 2020 incident easily detected three stations.