There are serious concerns about the long term affects of this vineyard development on the unstable soils upon which the community of Circle Oaks was constructed.

An update (November 2016) on this issue with new data is posted here.

  • The Walt Ranch Vineyard Conversion project proponents contend that development of the vineyard will reduce runoff rates from the areas where the property has been developed into vineyard.
  • Geohydrologist Greg Kamman opined that while this may be true on a temporary basis, as the soil recompacts, the runoff rates will accelerate post-project, affecting not only onsite erosion. The adverse effects will be also be notable downstream and offsite. See report by geohydrologist Greg Kamman, dated April 2, 2016, at pps. 11-13.
  • There are serious concerns about the dramatic increase in surface water run-off from this project site. It may potentially create erosion and land subsidence concerns, especially within downhill slopes from the Walt Ranch Vineyard Project. Its impact upon the residential community of Circle Oaks and also upon nearby residents of Monticello Road could be devastating.
  • Our experts have determined that the evaluation of impacts from surface water run-off from this project are inadequate and could pose serious risks to the community of Circle Oaks, given its history of unstable soils and the steep slopes upon which many of the residences are constructed. See report by geohydrologist Greg Kamman, dated April 2, 2016.
  • The sediment-laden runoff water will eventually end up in creeks, such as Capell Creek and Milliken Creek, endangering species of fish and amphibians (See Section regarding biological impacts.)
  • On June 4, 2008, the City of Napa Water Division wrote a letter expressing its concern about the amount of grading which may lead to an increase in the overall delivery of sediment and other pollutants into Milliken Reservoir. There was also a concern about the size of the project and the possible diversion of water that would otherwise normally enter the Milliken watershed. See written comments submitted by City of Napa, dated November 21, 2014 and April 4, 2016 in response to the Walt Ranch Project.
  • If there is an increase of sediment and nutrients that enter the reservoir from surface water run-off, it will create a cost to the public who rely on this water source to remove these pollutants—just as vineyard development created a problem and a public cost for the filtration system at Rector Dam. Rector Dam is the water source for Yountville and the Veteran’s Home.
  • The Walt Ranch Vineyard Conversion Project erroneously denies the existence of a wetland at the end of Circle Oaks Drive near the existing entrance to Walt Ranch (as accessed from Circle Oaks) in FEIR Comment 1139-4. However, as documented in the photos below, a wetland does indeed exist as documented by the Napa Sierra Club in their comment letter, dated April 4, 2016.


calla    erode4

Photographs taken at the end of Circle Oaks Drive near the existing entrance to the Walt Ranch property depicting wetlands and water from Capell Creek entering under road culvert. [Photographs courtesy of Nancy Tamarisk, Napa Sierra Club]

  • The Walt Ranch Project Proponents propose no mitigation measures with regard to their intent to realign the access road into the Walt Ranch from the end of Circle Oaks Drive which will require construction of a new roadway across an established wetland which includes Capell Creek, a blue line creek which is active year around.
drive west

View driving west toward Circle Oaks Water Plant.

drive east

View looking east toward Circle Oaks Drive.








Photographs taken at the end of Circle Oaks Drive depicting the existing entrance to the Walt Ranch property. The entrance road crosses at a 90-degree angle over Capell Creek. [Photographs courtesy of Nancy Tamarisk, Napa Sierra Club]

  • 121 collapse

    State Route 121, following prolonged period of heavy rains (March 11-13, 2016). [Photograph courtesy of David Heitzman]

    Land and soil instabilities are prevalent in the area, including most of the subdivision of Circle Oaks and are acknowledged by the EIR. Circle Oaks is built on unstable soils, comprising shale, mudstone, sandstone, and siltstone. Ancient landslides can be traced throughout this area, testifying to the mobility of the earth. Previous submissions by others concerned about the impact of this proposed project (including the Napa Sierra Club) have documented evidence of recent landslides, mudslides and road slippage.
  • The recent failure of SR 121 following a weekend of heavy rains in March of 2016 has raised grave concern for the adequacy of the evaluation of surface water runoff from nearby vineyards. The estimated cost of repair for this recent road failure exceeds $5,500,000.
  • The Walt Project proposes to deforest large areas in the ridge tops above Circle Oaks. We continue to contest the assertion that conversion of woodlands to vineyards will not adversely impact the homes and roads of the Circle Oaks community.
  • The correlation of the effects of the development of the Pahlmeyer Vineyards and subsequent multiple failures of SR 121 (directly below) are being evaluated by experts. The photo below, taken from Google Earth, documents the presence of large vineyards (Pahlmeyer) 400 yards above the road, on the ridge directly above the slump. While we cannot at present prove that the deforestation of the ridge top caused the damage, it is beyond dispute that trees, better than grape plants, capture, delay and disperse the runoff (both surface and subsurface) from heavy downpours, decreasing the chances of damage to both structures and infrastructures below them.

    GIS Satellite Image of Pahlmeyer Vineyards and downslope SR 121. [GIS Image enhanced and provided by Ron Tamarisk]

  • A graphic was created by Ron Tamarisk, a Circle Oaks resident, demonstrating the March 2016 road failure on Hwy 121 located 1.5 miles south of Circle Oaks and its relationship to the Pahlmeyer’s Waters Road Vineyard. The big question is what role the vineyard located 400 yards from the road loss contributed to this multi-million dollar repair project. It is believed that the washout occurred because of an accumulation of water on the western (vineyard) side of the road (NOT from the creek below UNDERcutting the road, as has occurred in the past). There is a swale that begins far above which deposits the water right at the location of the road failure. The vineyard above that undoubtedly and contributes water to this flow and is planted in a downhill direction that appears to intensify water runoff. Where is the directionality of vineyard planting discussed in the Walt Ranch FEIR? This is the very risk faced by the Circle Oaks community, with similar slope and similar soil.
  • For further information regarding concerns from surface water runoff, erosion, and project sedimentation, see report by geohydrologist Greg Kamman, dated April 2, 2016, dated April 2, 2016, at pps. 11-13.