FOCUS: Focal Center Utility Study for the United States

What was FOCUS?

  • FOCUS was a project of NADP’s Critical Loads Atmospheric Deposition (CLAD) Science Committee.
  • FOCUS was initiated in the fall of 2010 to develop a national critical loads database (NCLD) and coordinate input from members of the critical loads’ research community.
  • FOCUS was a multi-stakeholder effort to obtain, map and document ecosystem response to deposition through the use of critical loads.
  • The resulting NCLD is being used to share information among critical load researchers, assist sponsoring federal agencies with further implementation of critical loads in their programs, and collaborate with the UNECE on critical load topics.
  • FOCUS, as a project, was officially ended in October 2015. However, the NCLD is still actively supported and updated by CLAD.

FOCUS Phase 1

Phase 1 was completed in 2011 with release of the first version of the NCLD (March 2011) and Phase I report (September 2011).


Phase II was completed in 2015. The following were accomplished during FOCUS Phase II:

  • Created version 2.0 of the NCLD by expanding and improving the resolution of national-scale critical loads database that was created in Phase I, and making it more widely accessible.
  • Brought together scientists and practitioners with expertise to improve modeling and empirical critical loads estimates.
  • Identified gaps in data necessary for estimating critical loads and validating and parameterizing deposition and critical load models. Strategized, prioritized and initiated ways to address these gaps.
  • Identify and define US critical loads database and related infrastructure needs and suggest solutions.

For additional information on FOCUS, please see FOCUS Annual Reports 2011-2015 or contact Jennifer Phelan, CLAD Program Manager, at