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City of Pleasanton—Hidden Canyon Residences and Preserve Draft EIR Biological Resources FirstCarbon Solutions 3.3-41 https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/2148/21480016/EIR/3 - Draft EIR/21480016 Sec03-03 Bio Resources.docx Wetlands and Jurisdictional Features Impact BIO-3: The proposed project would not have a substantial adverse effect on State or federally protected wetlands (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means. Impact Analysis A formal wetland delineation has been conducted on the project site in 2016 and 2023. The USACE has issued a Jurisdictional Determination which determined that jurisdictional waters of the United States are present on the site in the form of Devaney Creek and its unnamed tributary to the extent of the OHWM on opposing banks. Additionally, the USACE determined that approximately 0.42 acre of seasonal wetlands identified in the northern portion of the site near Dublin Canyon Road were isolated and non-jurisdictional. The USACE issued a PJD August 15, 2024, which accepted all aquatic features identified on the map as jurisdictional including seasonal wetlands (0.54 acre), tributary waters (1.48 acres and 6,997 linear feet), seasonal wetland gulley (0.001 acre and 71 linear feet), and a roadside ditch (0.06 acre and 266 linear feet). All waters identified on the site including the creeks, ephemeral tributaries, and the seasonal wetlands would be subject to the regulatory authority of the RWQCB. The creeks on the site would also be considered jurisdictional by CDFW. All of Devaney Creek and its unnamed tributary will be preserved by the proposed project with a setback. The project is already sited to avoid and minimize impacts to Devaney Creek and its unnamed tributary; however, complete avoidance of the seasonal wetlands will not be due to the siting of the entrance road in the northern portion of the site. Approximately 0.25 acre of seasonal wetland on the site would be filled under the proposed project due to the entrance road from Dublin Canyon Road. Although these wetlands are densely vegetated by non-native species and appear to provide similar functions and value as the upland grasslands, filling of these features would require a permit from RWQCB and impacts to these features may be potentially significant. As noted in Impact BIO-2 above, the proposed project will also include the construction of an 18- inch outfall that will drain into the west side of Devaney Creek and a 24-inch outfall that drains into the east side of Devaney Creek near the vicinity of Dublin Canyon Road. Specific design details for the outfalls have not yet been determined. While these outfalls are intended to be above OHWM, they will impact a small amount of riparian habitat in the range of 0.03 to 0.06 acre. The applicant will need to comply with all State and federal regulations related to construction work that will impact aquatic habitats occurring on the site. Under the currently proposed project, the applicant is likely to require a permit from the USACE and RWQCB for the filling of seasonal wetlands in the northern portion of the site. Through compliance with all State and federal regulations, along with implementation of MM BIO-3, which describes avoidance and minimization measure, project impacts to State and federally protected wetlands would be reduced to a less than significant level under CEQA.