4.0 CUMULATIVE IMPACTS - Sacramento District - U.S. Army

4.0 Cumulative Impacts
Placer County’s population is expected to increase by 270,837 people from 2005 to reach a total of
570,709 by 2035 (SACOG 2008) and increase by 484,000 people from 2007 to reach a total of 811,000 by
2060 (Hausrath Economics Group 2008). Most of this growth is expected to occur in the cities and
unincorporated areas of western Placer County. The majority of the population and employment growth
requires land for urban/suburban residential, commercial, office and industrial uses, and associated
infrastructure and public support facilities (e.g., wastewater treatment plants, libraries, landfills, etc.).
Based on plans and proposals for development in the cities and the unincorporated areas and on
planning level assumptions about development density, an estimated 68,000 acres (28,000 hectares) of
land conversion would accommodate this growth, of which 57,000 acres (23,000 hectares) would be in
unincorporated Placer County and Lincoln. The remainder would be in the cities of Auburn, Loomis,
Rocklin, and Roseville (PCCP 2011). According to the PCCP, the far western portions of Placer County
are expected to be preserved.
As explained above, the Sacramento County 2030 General Plan identifies some growth areas to the south
of the Placer County southern boundary, within the study area. The area identified for growth is
designated for low-density residential uses. The remaining areas within the Sacramento County portion
of the study area are designated for agricultural uses, so would not likely be developed.
The study area also includes a portion of Sutter County. With respect to this area, the County General
Plan designates most of the area for agricultural and open space uses and a portion of it for development
of a new town (Sutter Pointe Specific Plan).
Figure 4.0-3, Converted Vernal Pool Grassland in Cumulative Study Area Circa 2060, shows the
additional areas of vernal pool grassland habitat within the study area that are anticipated to be
converted between 2010 and 2060 based on the projected growth in the area as reported in the PCCP and
other information. As shown in this figure, approximately 19,000 acres (7,700 hectares) of additional
potential habitat would be converted if the projected growth occurs in the study area.
Significance Thresholds
The contribution of the Proposed Action or an alternative to a cumulative impact would be considered
significant if the Proposed Action or an alternative would:
Result in a net loss of the Waters of the US;
Result in an unmitigated loss of vernal pool grassland habitat; or
Result in an unmitigated loss of wildlife foraging and movement habitat.
Impact Sciences, Inc. 4.0-16 Sierra Vista Specific Plan Draft EIS
USACE #200601050 July 2012