Aspen provided the air quality impact analysis in a joint EIR/EIS for the California State Lands Commission and the Monterey Bay National Marine Sanctuary (MBNMS). The report addressed installation of a unique undersea scientific observatory proposed by the Monterey Bay Aquarium Research Institute (MBARI). The MBARI will install and operate an advanced cabled observatory in the deep water of Monterey Bay to provide an infrastructure for undersea exploration, observation, and experimentation.

Installation of the undersea observatory involved on-shore staging and locally intense use of marine vessels. Along the cable route, emissions were quantified from support boats and the cable-laying vessel, including propulsion engines, auxiliary power generators, or hydraulic pump engines for the underwater plow or jetting devices. Consistency with local air quality attainment strategies and the federal General Conformity Rule were the focus of the analysis.

Aspen coordinated with the Monterey Bay Unified Air Pollution Control District (MBUAPCD) to determine whether the short-term emissions from marine vessels would be accommodated in MBUAPCD's 2004 Air Quality Management Plan and found that substantial mitigation would be needed to ensure that the construction effort did not obstruct implementation of the air quality plan. Mitigation involved MBARI paying funds for emission reductions from similar marine vessels or other tough-to-control sources like agricultural engines or school buses in the Monterey Bay area.

The Aspen analysis addressed the noise effects of construction and operation of this undersea observatory, which involves a science node at the end of 31.7 miles of submarine cable extending into Monterey Bay from the shore. The majority of the cable would be installed by a cable-laying vessel towing a hydraulically operated cable plow, and the first 0.89 miles of the cable would be installed from shore using horizontal directional drilling (HDD).

Low-frequency underwater noise would be caused by marine vessels, such as work boats and the cable-laying vessel, and by the main lay cable plow. The Aspen report summarized the underwater noise levels and worked with marine biologists to determine a radius of potential impact for marine mammals and other species of concern. Because onshore major drilling activities would occur in close proximity to the Moss Landing State Beach, noise from the equipment and disruptions to the State beach and Moss Landing Harbor required special mitigation.