Water conservation

Features - Water

Sustainable growers should be proactive and implement practices that conserve water and protect water quality.

November 12, 2010

In recent years, water issues have increasingly threatened the sustainability of the ornamental plant industry in California.

If you live in a part of the country where water is plentiful or where agricultural water quality regulations are not currently being enforced, don’t expect this to continue in the future.

Water supply concerns
In California, the average annual rainfall (about 21 inches) varies tremendously with geographic location and local topography. Rainfall is also seasonal – dry during the hot summer months, and wet for only a few months in the winter. Consecutive years of drought are common and have contributed to water supply shortages and fierce competition among water users.

The distribution of California’s rapidly growing population does not reflect water availability. Water is plentiful in the northern part of the state, but not in the central and southern regions where water is most needed. To remedy this situation, there is a massive statewide distribution system made of aqueducts and infrastructure that redistributes and conveys water to the drier, populous regions.

California’s largest source of agricultural water is the Sacramento-San Joaquin Delta, where water is pumped and transported long distances to the Central Valley and Southern California. The delta is facing ecosystem decline and threatened native fish populations, resulting in court-ordered pumping restrictions that greatly reduced water allocations in 2008 and 2009 to many California growers. Greenhouse growers were among the many agricultural producers who had to cut back their operations due to water restrictions. Idle greenhouse space is a much higher economic loss than idle fields.

The state’s water shortages have resulted in significantly increased water use fees. San Diego County growers, who rely heavily on water transported from the Colorado River and Northern California, pay some of the state’s highest fees, currently about $1,200 per acre feet. Water fees can be prohibitive to greenhouse production, especially when the economy is in a recession.

Many California greenhouse growers don’t use municipal water because they have their own wells. Approximately 30 percent of the state’s water supply is from groundwater, but salt-water intrusion due to overdrafts is becoming a major problem. Growers who draw from their own wells may face water shortages in areas of the state where salt-water intrusion has resulted from excessive pumping of groundwater.

California greenhouse growers who have poor water quality with high soluble salts are able to use it by filtering it with expensive reverse-osmosis systems.

Sometimes growers can blend reverse-osmosis water with other sources containing normal levels of micronutrients, thereby reducing the cost per gallon. However, there’s also an increased concern with what to do with the discharged waste brine from the reverse osmosis process, and this brine’s impact on the salt total maximum daily loads (TMDLs) in some watersheds.

Some California growers have access to reclaimed water, but in only a few areas of the state is reclaimed water successfully used in greenhouse production. In general, inconsistent supplies and cost limit the use of reclaimed water.

Some greenhouse operations are set up to capture and collect rainwater. Storm water collected from greenhouse roofs can sometimes be recycled. However, there may be local restrictions that prevent the recycling of greenhouse roof water.

Water quality issues
The Porter–Cologne Act of 1969 is the principal law governing water quality in California. The State Water Resources Control Board is the statewide water quality planning agency, and there are nine Regional Water Quality Control Boards.

The Porter–Cologne Act requires the regional boards to adopt water-quality control plans (basin plans) for watersheds within their regions. The regional boards also administer many of the Federal Clean Water Act’s provisions.

These include maximum daily loads for agricultural activities implemented for impaired water bodies in various areas throughout the state. Increased maximum daily loads will likely be enforced in the future.

The regional boards have taken a different approach to controlling runoff from agricultural lands. Currently, four of the state’s nine regional boards have each adopted “conditional waivers” or “conditional ag waivers” for irrigation runoff.

The conditional waiver allows the discharge to occur, but growers are required to take specific actions. These include the adoption of best management practices (BMPs) to prevent pollutants from entering water bodies, and monitoring downstream waters where agricultural lands drain.

Monitoring is typically accomplished through coalitions of agricultural entities, which provide more cost-effective results. But growers can also act independently.

A conditional waiver is good for five years, but it can be revoked at any time. The original conditional waiver that was adopted by the Central Coast Regional Water Quality Board expired this summer -- July  2010.

The state’s Central Coast is one of the most productive and profitable agricultural regions in the nation, reflecting a gross production value of more than $6 billion in 2008. More than 1,800 growers and farming operations participate in the current waiver program, representing 390,000 acres, or 95 percent of the commercially farmed land in the region.

Because conditional waiver monitoring data has continued to show agricultural loads that exceed water quality objectives set forth in its basin plan, the Central Coast Regional Water Quality Board developed a proposal for a new waiver in February 2010. The proposal would have required extensive record keeping and several layers of on-farm monitoring for every agricultural operation that was subject to public scrutiny.

Growers were concerned that the plan failed to consider the different types of agriculture, irrigation methods, topography and geography in the region. For example, the original proposal would have required separation of rainwater from container plants. This essentially meant that some outdoor nursery growers would have had to construct greenhouses in areas where greenhouse permits are impossible or difficult to obtain.

Fortunately, in July the Central Coast Regional Water Quality Board extended the ag waiver another year so that alternative plans for a new waiver could be examined. A coalition of more than 50 farm groups and individual growers have presented an alternative plan that the Central Coast Regional Water Quality Board will consider along with alternative plans proposed by other groups. Furthermore, the California Association of Nurseries and Garden Centers has been working with nursery and greenhouse growers and the Central Coast Regional Water Quality Board to develop strategies that would meet the basin water quality objectives while allowing the ornamental production industry to remain sustainable.

Be proactive
If you don’t have similar scenarios in your state, you’re lucky. Be proactive and regulate yourself before others do. If you have irrigation runoff, or even just storm runoff, start implementing appropriate best management practices to contain as much of the runoff as possible onsite. Implement precise irrigation management practices to conserve water. For a list of management practices, go to http://ceventura.ucdavis.edu/Ag_Water_Quality_Programs/ and click on “Checklist for Assessing and Mitigating Runoff in Greenhouses and Nurseries.”

Julie Newman is environmental horticultural farm adviser, University of California Cooperative Extension, jpnewman@ucdavis.edu.