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6.3.11 AIR QUALITY Past development in San Joaquin County and throughout the San Joaquin Valley has resulted, in combination with meteorological conditions and transport of pollutants from other air basins, in substantial to severe air quality problems in the San Joaquin Valley Air Basin(SJVAB).As described in Section 4.12, "Air Quality",the SJVAB is in severe nonattainment with state and federal ozone standards and nonattainment with state and federal standards for respirable particulate matter 10 microns or less in diameter(PMto).As a consequence,the San Joaquin Vr31ey Air Pollution Control District(SJVAPCD)is required to submit a plan demonstrating reductions in the emissions inventory of 300 tons per day by 2005-2010.However,a voluntary reclassification to extreme nonattainment for ground-level ozone is in process and,if adopted,would allow additional time to implement emission reduction measures. SJCOG projects population in San Joaquin County to grow from 563,600 in 2000 to 900,300 in 2025,an increase of 330,700. SJCOG bases its air quality attainment planning on projections of countywide growth and has indicated(along with SJVAPCD staff)that,in general,higher-than-projected growth in one community, such as College Park,usually translates to lower-than-proj ected growth in another and that countywide growth trends would not be likely to change on the basis of development in one community(Klob 2003).In short, SJCOG and w SJVAPCD have assumed a substantial level of cumulative development over the next 25 years in their air quality planning, and development of individual projects would not alter attainment of air district plans. It is important to recognize that SJVAPCD has already seen substantial progress in meeting attainment status for ozone; federal ozone standards were exceeded on more than 70 days per year between 1980 and 1990, and in the past 5 years the number of exceedances has been steadily reduced to an average of approximately 30 days per year despite substantial population growth. Still, it is uncertain whether,despite the best efforts of regulators and constantly improving control technologies,attainment will be reached on schedule. Much of the past development in the project region has occurred to meet demands for more affordable housing for people employed in the San Francisco Bay Area.Increased commuting associated with this development scenario has contributed substantially to existing air quality problems in the SJVAB.The project would result in an individual significant air quality impact with respect to long-term regional emissions. Emissions attributable to the proposed project,along with emissions from other reasonably foreseeable future projects in Mountain House and the SJVAB as a whole,would continue to contribute to long-term increases in emissions that would exacerbate .� existing and projected nonattainment conditions in the SJVAB. Thus,the proposed project would contribute to a significant and unavoidable cumulative impact.The proposed project's incremental contribution to that cumulatively significant impact,therefore,is itself cumulatively considerable.3 Because of the nonattainment status of the SJVAB and the large disturbance area associated with the College Park project,the proposed project is considered to result in significant and unavoidable construction-related air quality impacts,even with implementation of mitigation measures required by SJVAPCD, as identified in Section 4.12, "Air Quality."Assuming that all related projects also implement all feasible construction emission control measures consistent with SJVAPCD guidelines, construction emissions on a project-by-project basis could be less .. than significant,or significant and unavoidable,depending on the scale of the project and other factors.Because of the large scale and number of related projects,taken in total and combined with the nonattainment status of the SJVAB for PM o, construction-related emissions would result in a significant and unavoidable cumulative impact.The proposed project would cause a cumulatively considerable(significant and unavoidable) incremental contribution to this cumulatively significant impact from the College Park project together with all related projects.Given that compliance with applicable rules and regulations would be required for the control of stationary-source emissions of toxic air contaminants(IACs),both on-and off-site,the project's contribution to r 3 Only eliminating or severely limiting both project and regional development would avoid significant cumulative impacts on regional air quality,and this is considered infeasible because it would require actions beyond the lead agency's(the County's)jurisdiction and could potentially be illegal(i.e.,developers have a rigbt to reasonable economic use of their land). College Park at Mountain House Specific Plan III Draft El EDAW San Joaquin County 6-13 Cumulative Impacts