I'm also working for a group challenging the Walt Ranch Vineyard project. In looking at the bigger regional picture and number of winery creation/expansion projects in Napa, I see the need/value in doing a cursory accounting of the cumulative project water demands for all the new winery/development projects. In my reviews of almost all hydrology studies in support of Napa/Sonoma vineyard expansion, I see a chronic pattern of incomplete cumulative hydrologic impact assessments. The status quo is to only look at potential impacts to wells on adjoining properties, without acknowledging, less analyzing, that many of these projects are located in the upland recharge areas that feed into the valley bottom alluvial aquifer. For example, I'm just becoming aware of the Suscol Mtn. Winery project. In addition to Walt and maybe Mtn. Peak, at least the two larger ones are located within the upper watershed supplying groundwater recharge to the depleted MST aquifer. The MST is a County designated groundwater deficient aquifer area, that is subject to specific (reduced) groundwater withdrawal rates and "fair use" practices/oversight. Do you know of any more projects being proposed in a 10- to 20-mile range of these (esp. Mtn. Peak) projects?

From my technical perspective, having a regional accounting and mapping of all existing vineyards/homes along with new or proposed projects would allow for a better assessment of sustainable water supply. I think an important note from this perspective is that there is potential cumulative impact of new projects on the groundwater supply of existing vineyards, even those on the valley floor. The timing for pressing this point is ideal - California just passed several bills (last month) that impose groundwater management and reporting requirements on local agencies (likely Napa County in this case). This new law mandates that local agencies develop groundwater sustainability plans, backed with real numbers and annual reporting of basin-wide extraction volumes and groundwater storage volumes.

Again, your postings and website has been very informative and enlightening to me. You also seem to be abreast of all the local area advocacy work/groups in the neighborhood. So, any insight into the location and information of other vineyard expansion (or other) projects in the vicinity of Mtn. Peak would be helpful information.

Oct 6, 2014
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