Domaine Chandon began using recycled water in 1994 as a supplimental source of irrigation water for their Carneros ranch. The Sonoma Valley Treatment Plant was required to reduce discharges of treated water into the slough and offered to construct a distribution system to supply water to vineyards. Start up of the distribution network proved to be difficult with many improvements needed to ensure a reliable water source to the end users. The original system was underdesigned for the volumes expected, water quality of stored recycled water was poorly managed, and filtration changes were needed at user pump stations. Filtration needs changed as the algae was able to pass the 120 mesh screens and increase the back wash needs of sand media filters. Safety requirements stated that recycled water could not be used two weeks prior to harvest, which required a reserve of fresh water for the end of the season.
Since the initial start up, many improvements have been made to the system. Chandon actively participated in the redesign of a portion of the distribution network, increasing pipe sizes to improve distribution volumes. New Amiad filters were installed to handle the algae problems encountered in both the Sonoma Valley distribution system and at the end user pump stations. Transmission lines were extended to reach more users and coordination with the facility management improved. Continued improvements to the Sonoma Valley Treatment Plant have allowed the water to be used up to the day of harvest, while better management of stored water has improved quality of delivered water.
Currently, Chandon uses about 275 acre feet of recycled water for 700 producing acres in Carneros. Access to this source of water has allowed irrigation amounts to double, leading to increased production and improved vine health, while maintaining vine balance. Before access to recycled water, annual irrigation was 50-100 gallons per vine in a normal year. With the use of recycled water, irrigation was nearly doubled to 125-180 gallons per vine. In the mid 90’s, an irrigation trial was conducted to ensure that the increased irrigation was not adversely affecting fruit quality. The results show that doubling the irrigation amounts added 40% to the crop load, while having no significant impact on fruit quality. Although this trial was for sparkling wine, still wine producers can reap the benefits of increased irrigation later in the season when previous water supplies were running low. An additional trial was set up to test the soil for accumulation of heavy metals. Results show no build up over three years. A follow up test could be done at 10 years to confirm long term deposits.
There are a few requirements that users need to follow. Monthly reporting of water use, posting pump stations and reservoirs used to store recycled water, and training of personnel in the proper precautions regarding exposure to recycled water. These requirements are not very burdensome when compared to the benefit of a reliable water source. If this water is used for spray applications, pH should be tested and adjusted prior to mixing of the spray materials.
The use of recycled water allows the opportunity to increase vine densities, while maintaining current irrigation levels on a per vine basis. Chandon will be inceasing average vine density from 900 to 1500 vines per acre over the next several years. Another future benefit is that more water will be available in drought years when fresh water storage may be insufficient. Environmental benefits include reducing discharge of treated water during the low runoff months of summer and fall.