Almond growers rely on good water quality to ensure both a healthy tree and a healthful crop. Growers also need to protect surface- and groundwater from runoff, spray drift and/or leaching by following good management practices.
Almonds have a relatively low tolerance for saline conditions; however, the nature of irrigated agriculture is that salts carried in the irrigation water are added to the soils and accumulate there. Different water sources carry different levels of salts. For example, groundwater on the West Side of the San Joaquin Valley is generally naturally high in salts, while surface water from snowmelt is very low in salts. Depending on the sources of water available to the grower, a part of irrigation management is to ensure enough good-quality water is applied to leach salts below the root zone. Minimizing the addition of salt to the soil and removing salts by leaching are critical for continued almond production.
There is an inherent conflict between the goals of maintaining groundwater quality while maintaining a productive irrigated agriculture. These issues are being addressed by the Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS). CV-SALTS members include entities involved with water management, irrigation districts and some growers, as well as the Central Valley Regional Water Quality Control Board.
- Salinity Management in Orchards by Maxwell Norton, UCCE Merced County
- Irrigation and Salinity Management in a Dry Year(s) by Terry Prichard, UCCE San Joaquin County
Growers in California have recently been tasked with protecting groundwater quality under the Irrigated Lands Regulatory Program.
Groundwater quality issues include nitrates that primarily come from agriculture, salinity that is often naturally occurring, a few pesticide issues (primarily legacy issues) and issues such as arsenic, which is primarily from natural sources.
Monitoring of groundwater in the Central Valley has detected a number of sites with elevated nitrate levels. Nitrates affect the ability to use the water for drinking. Nitrate is a form of nitrogen that plants can take up as one of their nutrients; however, it also moves easily in water and therefore leaches easily into groundwater. The Central Valley Regional Water Quality Control Board, under the Irrigated Lands Regulatory Program, has developed a Groundwater Quality Protection Strategy that addresses the issue of nitrates and other contaminants in groundwater. With some care, growers can minimize — but not necessarily eliminate — nitrate leaching from their fertilization practices.
The nitrogen budget calculator at the California Almond Sustainability Program website is a tool that growers can use to more precisely apply nitrogen to orchards in the amounts that the crop demands, resulting in less potential nitrogen leaching into groundwater.
In some instances, pesticides have shown up in groundwater. Currently, California’s Department of Pesticide Regulation (CDPR) limits the use of pesticides that have the potential to leach in areas where the groundwater is more vulnerable; these are called Ground Water Protection Areas (GWPA). In addition, CDPR monitors for pesticides that could possibly leach, based on their chemical characteristics.
Preventing Irrigation and Storm Water Runoff
A comprehensive surface water–quality regulation for agriculture in the Central Valley of California was passed in 2003 by the Central Valley Regional Water Quality Control Board. Through participation in the Irrigated Lands Regulatory Program watershed coalitions throughout the San Joaquin Valley, almond growers are meeting their legal requirements under the Clean Water Act to protect water quality. The coalitions also help almond growers take steps to reduce potential levels of farm waste in irrigation drainage or rainwater runoff.
Monitoring and ultimately reducing discharges of pesticides, nutrients and sediments into waterways and groundwater is the goal of almond growers in California’s Central Valley. To help them meet that goal, the Almond Board of California funds research on ways to control runoff from orchards and prevent it from contaminating surface and groundwater.