MID water transfer—on potentially affected resources in the Tuolumne River watershed and downstream water bodies would be less than significant, and no mitigation measures would be required. The one exception is that the WSIP Program EIR identified potentially significant—but mitigable—impacts on terrestrial biological resources in the Tuolumne River watershed due to an increase in average annual diversions from the Tuolumne River and the associated modifications in releases from Hetch Hetchy Reservoir. This impact was identified for the reach of the river between Hetch Hetchy Reservoir (O’Shaughnessy Dam) and Don Pedro Reservoir, with particular impact on meadow and alluvial features in this reach, including the Poopenaut Valley. The impact on meadow and alluvial features would occur under a range of diversion increases, from the 2 mgd of the adopted WSIP up through the 30-mgd diversion increase proposed under the original WSIP project. The impact would result from both the increase in diversion as well as the changes in system operations adopted as part of the WSIP.

The proposed water transfer agreement would contribute to this potential impact on the Tuolumne River associated with changes in the SFPUC’s existing reservoir release pattern from Hetch Hetchy Reservoir that, in some years, could lead to flow changes that could adversely affect streamside meadows and other alluvial deposits. The SFPUC is implementing adopted WSIP Program EIR mitigation in order to reduce potential impacts on the streamside meadows and other alluvial deposits along the Tuolumne River below this reservoir to less-than-significant levels. The SFPUC’s mitigation action will, in effect, address this impact and remedy it such that it would not continue to be an impact for water transfers such as is proposed between OID and Brisbane for the Baylands.

Conclusion: As described in the WSIP Program EIR, a significant impact on meadow and alluvial features in the reach of the Tuolumne River between Hetch Hetchy Reservoir (O’Shaughnessy Dam) and Don Pedro Reservoir, particularly within the Poopenaut Valley would result from diversions of water being held in the Hetch Hetchy Reservoir. Thus, the proposed water transfer agreement with OID, in combination with the SFPUC diversions addressed in the WSIP Program EIR would result in a cumulatively significant impact, although mitigation measures set forth in the WSIP Program EIR, including a program of controlled releases (WSIP FEIR Mitigation Measure 5.3.7-2), would be implemented to mitigate impacts of that project to a less than significant level.