Drainage

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Shallow Groundwater Maps

Drainage

"Why Land Retirement Makes Sense for Westlands Water District" , (PDF, 110K)
Westlands' drainage problem has been occurring for decades because dense soil and clay layers at shallow depths prevent the unused irrigation water from percolating into the deep aquifer. As irrigation water passes through the soil, it picks up salts and other natural elements before it builds up -- or "perches" -- above these impermeable clay layers. Without natural drainage, the salty water can encroach into the crop-root zone, reducing yields and crop mix, and eventually eliminating crop production. It is one of the oldest and most perplexing problems facing farmers in irrigated areas world-wide.

Westlands' farmers have been without drainage service since the San Luis Drain was closed in 1986. In the San Joaquin Valley, about 1.5 million of the 5.6 million irrigated acres have drainage-related problems. In Westlands alone, over 200,000 acres have saline groundwater within 10 feet of the soil surface. Many farmers with drainage-impacted lands have been able to keep their land in production by improving irrigation efficiency and changing cropping patterns. Shallow groundwater conditions fluctuate significantly with hydrologic conditions and the availability of surface water supplies. But, without a long-term solution, the drainage problem will become more widespread and severe throughout the west side.

Westlands remains committed to finding an environmentally sound and economically feasible method to manage drainage water. There is no single solution to the subsurface drainage problems on the west side. Rather, there will likely be a combination of "fixes" to help manage and safely dispose of drainage water.

Another source of information is the DWR San Joaquin District, Division of Local Planning and Assistance site.


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Shallow Groundwater Maps	Drainage
	"Why Land Retirement Makes Sense for Westlands Water District" , (PDF, 110K) Westlands' drainage problem has been occurring for decades because dense soil and clay layers at shallow depths prevent the unused irrigation water from percolating into the deep aquifer. As irrigation water passes through the soil, it picks up salts and other natural elements before it builds up -- or "perches" -- above these impermeable clay layers. Without natural drainage, the salty water can encroach into the crop-root zone, reducing yields and crop mix, and eventually eliminating crop production. It is one of the oldest and most perplexing problems facing farmers in irrigated areas world-wide. Westlands' farmers have been without drainage service since the San Luis Drain was closed in 1986. In the San Joaquin Valley, about 1.5 million of the 5.6 million irrigated acres have drainage-related problems. In Westlands alone, over 200,000 acres have saline groundwater within 10 feet of the soil surface. Many farmers with drainage-impacted lands have been able to keep their land in production by improving irrigation efficiency and changing cropping patterns. Shallow groundwater conditions fluctuate significantly with hydrologic conditions and the availability of surface water supplies. But, without a long-term solution, the drainage problem will become more widespread and severe throughout the west side. Westlands remains committed to finding an environmentally sound and economically feasible method to manage drainage water. There is no single solution to the subsurface drainage problems on the west side. Rather, there will likely be a combination of "fixes" to help manage and safely dispose of drainage water. Another source of information is the DWR San Joaquin District, Division of Local Planning and Assistance site.