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

4.0 Cumulative Impacts
area. Based on the Applicant’s proposed mitigation, the vernal pool compensatory
mitigation ratio, including preservation, for the Proposed Action would be 3.8:1 and for
other waters of the US, the mitigation ratio would be 2.4:1.
Because all development projects, including the Proposed Action, would comply with the
no net loss policy and, to the extent there are small losses of wetlands that fall under
nationwide permits and are not compensated by replacement wetlands, such small losses
would not represent a substantial cumulative loss of wetlands. As explained earlier, the
USACE required approximately 1,254 acres (507 hectares) of compensatory mitigation for
projects within the study area to mitigate the loss of 438.93 acres (177.63 hectares) of
wetlands in the study area since 1990. As Table 4.0-1 shows, USACE required
compensatory mitigation of vernal pool losses at the rate of 3.15 acres for every acre
(3.15 hectares for every hectare) filled, and for losses of other non-vernal pool waters of
the US at the rate of 2.71 acres for every acre (2.71 hectares for every hectare) filled. For
losses through the Department of the Army permitting program, any cumulative effect
on wetlands and vernal pools would be expected to be less than significant, and the
Proposed Action’s contribution would be rendered less than significant with the
implementation of Mitigation Measure BIO-1a which would ensure compliance with the
USACE requirements for mitigation of wetland impacts. In addition, the USACE will
impose Mitigation Measure CUM BIO-1 on future development in the study area to
further minimize loss of wetlands and vernal pools.
No Action
Alt.
Alts. 1, 2, 3
& 4
The No Action Alternative would not result in filling of any wetlands on the project site
because filling of the waters of the US would be avoided by design. Therefore, this
alternative would not contribute to the cumulative impact on wetlands, and no
mitigation is required.
Although the acreage of wetlands filled under each alternative varies, Alternatives 1, 2, 3,
and 4 would result in the loss of similar types of wetlands and vernal pools. The
alternatives would therefore also contribute to the cumulative impact on wetlands.
However, as with the Proposed Action, development under any of the alternatives
would be required to comply with the federal and state regulatory programs for the
protection of wetlands and would implement Mitigation Measure BIO-1b to provide
compensatory mitigation at ratios acceptable to the USACE for wetland impacts.
Therefore, the contribution of any of the alternatives to any cumulative effect on
wetlands and vernal pools would be rendered less than significant. In addition, the
USACE will impose Mitigation Measure CUM BIO-1 on future development in the
study area to further minimize loss of wetlands and vernal pools.
Impact Sciences, Inc. 4.0-19 Sierra Vista Specific Plan Draft EIS
USACE #200601050 July 2012