irrigating vinesThe Walt Ranch Vineyard Conversion Project will have uncertain impacts upon the Sonoma Volcanics aquifer that will supply 100% of the water needs for this project. The experts agree that the fractured nature of the Sonoma Volcanics make it difficult, if not impossible to predict with any degree of reliability drawdown in nearby wells through use of groundwater models. “The DEIR admits great uncertainty about the impacts to the aquifer from the Project’s groundwater withdrawal.”

See report submitted by geohydrologist Matt Hagemann, PG, CHG, QSD, QSP, SWAPE Technical Consultants, dated November 19, 2014.


Nov. 1, 2016. There are certain changes in water quality and quantity that are accepted signs of distress upon an aquifer. They are typically a drop in water pumping volume, longer recharge times between pumping, and change in water quality. Increased mineral content which dramatically affects water quality is a sign that the aquifer is in a state of distress. As water quantities are drawn down in an aquifer, mineral content intensifies. Increased demand on the aquifer could result in increased concentrations of mineral such as iron oxide.  This is one concern raised by community representatives is recent meetings with each Supervisor. What will happen if the drought continues indefinitely and the Walt Ranch project withdraws an estimated 50,000,000 gallons more annually from this already distressed aquifer?

  • The Walt Ranch proponents suggest in the FEIR that the aquifer from which both Walt Ranch and Circle S Ranch will draft is capable of recharge of 486 acre feet per year, which is disputed by geohydrologist Greg Kamman, PG, CHG, in his report dated April 2, 2016, at pps. 10-11.
  • The estimated combined water usage between The Walt Ranch and the Circle S Ranch is estimated by the project proponents at 433.6 acre feet per year. However, as demonstrated by the letter submitted by the Napa Sierra Club, the estimated water usage is substantially understated and is more accurately estimated at 498 acre feet per year, significantly over-drafting the aquifer’s ability to recharge and not including the 13,000,000 gallons of water used annually by Circle Oak’s residents.
  • The ability of the aquifer to withstand the strain of cumulative effects from the addition of vineyard drafting is questionable at best. Testing of water levels and the ability of the aquifer to replenish heavy drafting is concerning where “slow recovery” is noted in at least one of the Wells (WR-5). Also of great concern is that most of the well testing was done in 2009, well in advance of the onset of the 4 or more years of drought conditions which have been experienced state-wide and most certainly at the project site. Under current drought conditions, 239 days of pumping from the aquifer will likely have a very dramatic impact on the water table for local residents who depend on shallow wells to provide water to their homes and small ranches. (See comment letter by Dan Mufson, dated November 19, 2014).
  • The experts disagree on how much water is actually available in the shared aquifer (with Walt Ranch). It is situated deep within the Sonoma Volcanics and is not susceptible of being accurately quantified. The aquifer’s attributes are described as having variable degrees of permeability and the interconnected fractured layers limit both the storage volume and the vertical and lateral movement of groundwater. See report prepared by geohydrologist Greg Kamman, PG, CHG, dated April 2, 2016, at pps. 10-11.
  • faucetThe community of Circle Oaks depends on the existing water aquifer shared with the Walt Ranch to provide a clean and reliable source of water for about 185 homes and for future homes not yet constructed.
  • Similarly, residents of Monticello Road and Atlas Peak could also experience serious declines in the water table affecting their wells including loss of water which may require substantial and expensive upgrades to their existing wells. The only wells that will have any water are the deep commercial agri-wells at Walt Ranch.
  • There will be little or no warning if or when the aquifer is depleted due to over-drafting. Should this occur Circle Oaks and nearby residents who depend on this aquifer will be left without a reliable water supply.
  • A further far-reaching potential for further depletion of supplies in the Milliken-Sarco-Tulucay (MST) aquifer is a serious concern, in that this aquifer is already very stressed and severe water conservation measures have been implemented. The experts are in disagreement about whether the watershed where the Walt Ranch is situated is connected to the MST aquifer; however, a strong argument can be made that they are interconnected and the health of the MST aquifer is dependent upon the health of the watershed where this project is being proposed.
  • Edwards Engineering (Edwards) of Napa prepared a report titled “Hall Wines, LLC, Walt Ranch, Vineyard Development Project, Preliminary Water System Master Plan,” dated November 12, 2012 ” which purports to estimate the amount of annual ground water usage by this Project. Their calculations are based upon the amount of groundwater required to irrigate 347 acres of vineyards, including frost protection for 100 of the planted vineyard acres. Vineyard density is designed at a maximum of 2,420 vines per acres with irrigation demands calculated at .5 acre/foot per acre, calculated at 213.5 acre feet or about 69,406,354 gallons of water being removed annually from the aquifer according to Appendix D to the Erosion Control Plan, at pages 256-257.
  • In order the meet demands for irrigation of the vineyard, the Walt Ranch Vineyard conversion project proposes to install 5 deep bore wells (WR-1, WR-2, WR-3, WR-4 and WR-5) and construct a total of six reservoirs on site for use by the vineyard for watering and frost protection. Two of the six reservoirs were previously approved for construction upon application of the previous property owner and are proposed for recreational use and for fire control purposes unrelated to the project. Water will be pumped from ground wells into these storage reservoirs for use because water demand exceeds well pump volume at times such as for frost protection. The proposed wells and reservoirs are in Milliken Creek watershed/drainage basin (Atlas Peak). If their pumps operate 18 hours/day, pumping will occur for 239 days a year.
  • The revised project, if approved, estimates 294 acres of vines will be planted at a planting density of 2,420 vines per acre and continues to rely upon previous estimates that irrigation for frost protection demands will result in only .5 acre foot per acre to irrigate the vines. However, estimates of water usage by the proposed vineyard project are grossly inaccurate. See comment letter by David Heitzman, undated, submitted April 1, 2016.
  • In 2012, UC Davis released a study entitled “Sample Costs to Establish a Vineyard and Produce Winegrapes-North Coast Region (Napa County)”. The study reveals released a study revealing that the minimal amount of water required to sustain grape vines on an annual basis increases as the vines age, reaching 100 gallons per vine by the third growth year. The report states that based upon a planting density of 1,555 vines per acre, water usage can be expected to be .5 acre feet per year. (Calculations for water usage are calculated by multiplying the number of vines by the number of acres planted.) For further specifics, please see the UC Davis study.
  • Based upon the discrepancy in the planting density, the water usage estimates are off by at least 47%. When coupled with the use of water for frost protection, the Walt Ranch Vineyard Conversion project will use nearer to 291 acre feet of water per year or 94,822,766 million gallons!
  • For further detailed discussion about the discrepancy in calculation of estimated water usage by Walt Ranch Project Proponents, see the FEIR comment letters submitted by Nancy Tamarisk, Napa Sierra Club dated April 4, 2016, and David Heitzman, undated, submitted April 1, 2016.
  • drought signA prolonged drought and demonstrable climate change is working in concert to prevent the aquifer from recharging at historic rates. Watersheds are already showing signs of severe strain in the Napa Valley. Geohydrologist Greg Kamman contends that the Walt Ranch Vineyard Conversion project would contribute to a significant adverse impact on groundwater resources by reducing recharge of the MST Groundwater Deficient Area. His findings are based upon his opinion that the Walt Ranch project has used an inflated recharge rate and have not accurately calculated available project water supply. See report prepared by geohydrologist Greg Kamman, PG, CHG, dated April 2, 2016, at pg. 10.
  • There are no guarantees by the current project developers that water will be available for future use should Hall-Brambletree sell any or all of the 35 pieces of acreage which comprise the existing Walt Ranch.
  • The cumulative impacts in the DEIR analysis for pumping of the aquifer under the Walt Ranch Vineyard Conversion Project fails to include any consideration of (1) a severe drought scenario (2) a rainfall scenario that relies upon records from the Napa State Hospital for its annual average and (3) pumping from all wells in the nearby vicinity. Expert Matt Hagemann stated in his report that the EIR should be revised to model for cumulative impacts.
  • These cumulative impacts would take into consideration pumping from the COCWD well in combination with groundwater recharge for an average rainfall year (consistent with the Napa State Hospital rainfall records) and during a severe drought for a modeling of a true representation of the best and worst case scenarios. See report submitted by geohydrologist Matt Hagemann, PG, CHG, QSD, QSP, SWAPE Technical Consultants, dated November 19, 2014.
  • Groundwater depletion has become a state-wide concern, especially during the recent prolonged drought which shows no signs of abating. The effects of the current drought are dramatically apparent in this NASA GRACE Satellite imageNASA GRACE