All Issues

California has changed considerably since 1957, when the California Water Plan was first formulated as a guide for the orderly and coordinated control, protection, conservation, and utilization of the states water resources.

Planning for water supply and for land use in agricultural areas has taken on new significance with enhanced public environmental awareness, new anti-pollution legislation, high costs of construction and energy, and increased economic opportunities for specialized agricultural commodities.

Water reclamation, considered by many to be the neglected stepchild in water resources planning, is about to come into its own with recent passage by the State Water Resources Control Board of a “Policy and Action Plan for Water Reclamation in California.”

California foothill and mountain watershed lands are the primary runoff-producing areas in the state, yielding about 95 percent of the usable water supply. Nearly 65 million acres of forests, brushlands, and mixed woodlands and grass areas comprise the state's wildlands. Of these, the vegetation zones most adaptable for multiple land-use management are the brush (chaparral) and woodland grass cover types. These areas are generally situated in the lower and intermediate elevations on the mountain slopes surrounding the agricultural valleys and are used principally as range-lands. Surveys of vegetation and land use indicate over 30 million acres of such lands could be managed to enhance their productivity for watershed protection and water yield, as well as forage and wildlife habitat.

If adequate water supplies are to be continually available, and if Periods Of drought are to be dealt with effectively, management of ground water is essential on every farm and in every city county, water district, and region using ground-water resources.

Development or conservation? Build new dams and canals or eliminate inefficient and wasteful uses? New water development has not been eliminated as a possible future alternative. For the moment, however, conservation of existing supply and increased efficiency of use seem to dominate decision-making processes. A major problem to be resolved thus becomes: How do we get people to stop wasting water and use it more efficiently?

A 50 percent increase in salinity of Colorado River water has been projected for the turn of the century—if nothing is done to slow the present rate of increase. In a three-year research project, University researchers from the Department of Land, Air and Water Resources; the Department of Agronomy and Range Science; and Cooperative Extension determined the detrimental agricultural effects of such an increase.

Californians are acutely aware that water is a valuable and scarce resource and are concerned about protecting its quantity and quality. Irrigated agriculture, the states biggest water user, depends on good-quality water; it also degrades the quality of the drainage water. Supplying irrigation water and disposing of drainage water account for a significant part of our fossil energy consumption. Furthermore, even though irrigated agriculture is crucial to the economy and makes a substantial contribution to supplying the worlds need for food, it must compete with other demands—municipal, industrial, and recreational. The question, then, is what can be done practically to conserve water, in quantity and quality, while maintaining a viable irrigated agriculture.

Irrigation is a major management consideration in cotton production. The plants require water delivered at intervals through 65 to 85 percent of the growing season. Not only is water a significant production cost, but its regulation through proper scheduling provides a unique opportunity to control plant growth and development in a way that favors high productivity. Such regulation requires an understanding of how cotton responds to water. This report summarizes several long-term cotton irrigation studies in the San Joaquin Valley. The results apply to conventional plantings with rows spaced 38 to 40 inches apart and normal plant populations.

The U.S. Department of Agricultures Agricultural Research Service and the Bureau of Reclamation have developed a new scientific tool for determining when to irrigate and how much water to apply to specific crops. This Irrigation Management Service (IMS) uses a computer program that takes meteorological data and calculates the rate at which various crops are using water; performs various bookkeeping chores; and forecasts the date and amount of the next irrigation for individual fields and

Drip irrigation first appeared in California agriculture in 1969 or 1970. Enthusiasm rose rapidly because of the attractive newness of the method and because of high hopes for substantial water saving. With water in California both costly and scarce, the prospect seemed inviting.

The Salinas Valley shows promise of becoming a distinctive new region for growing premium wine grapes. To make the most of the cool and windy climate, however, particular irrigation management practices are required. Irrigation itself is a necessity, because annual rainfall is much lower than in the nonirrigated vineyard areas north of the San Francisco Bay, and because root depths are characteristically shallow—most of the vineyards are on old terrace soils with shallow restricting layers in the form of clay pans or abrupt stratified zones. In previous tests, we have shown that nonirrigated or minimally irrigated grapes on shallow soils in Salinas Valley are very deficient in both yield and quality compared to carefully irrigated vines.

The west side of the San Joaquin Valley between Tracy and the Tehachapi Mountains has developed or will develop drainage problems. Ultimately, about 1½ million acres will be affected. Agricultural production could be reduced up to 80 percent in the most seriously affected areas.

The Tulare Basin, consisting of the southern half of the San Joaquin Valley, is a water-short area, and efficiency of use is quite high.

In an irrigated agricultural system, the fate of nitrogen in the soil is inescapably linked to water management. This has been confirmed by recent U.C. research into the relationship between applied nitrogen, crop yield, and nitrogen pollution potential.

In early 1973, the University of California Committee of Consultants was requested by the State Water Resources Control Board staff to submit a set of guidelines for interpretation of water quality for agriculture. These were to set forth a method of agricultural water quality evaluation and also suggest numerical guidelines that could be used in the comprehensive water-quality management plans then being prepared to manage the water resources of each of the states 16 water basins.

In monitoring wastewater discharges for salts as a measure of salt management, two parameters must be considered: (1) salt concentration of the effluent and (2) total mass emissions of salts.

The content of nitrogen, and nitrate in particular, of some ground- and surface-water supplies is of much concern because of the potential health hazard to infants (methemoglobinemia) and to livestock. It also may contribute to the eutrophication (over-enrichment) of surface bodies of water and may delay the ripening of certain fruits, vegetables, and other crops.

Today's concern for the quality of our environment has prompted investigations of the effects of irrigated agriculture on the underlying ground water. The work reported here is one phase of an intensive soil nitrate project being conducted by soil and water scientists of the U.C. Agricultural Experiment Station funded by the National Science Foundation's program on Research Applied to National Needs (RANN).

The Sacramento-San Joaquin Delta carries about 42 percent of the natural runoff of the state. It is high in biological productivity, receiving nutrient-laden waters from municipal and industrial activities and from intensively cultivated agricultural land surrounding the basin. The Delta supports important freshwater fisheries and serves both as a nursery ground for marine species and as an access route and habitat for young and adult anadromous species important in the states sport fishery.

Much attention is being focused on irrigation return flows as a result of recent legislation on water quality and pollution control and the concern for water and energy conservation. State-wide, surface irrigation return flows are nearly nonexistent where water normally is scarce or expensive. This report describes the variations in flow and quality characteristics of surface drainage waters from two irrigation districts in Californias Central Valley, and the factors that contribute to such variations.

Compared to most food crops, floricultural and ornamental greenhouse crops use large amounts of irrigation water per square foot of production area. This is because of shallow soils in containers and raised beds and because of high leaching requirements when nutrient solutions are added. As a result of the large amounts of water generally being leached and its high nutrient content when fertilizers are injected into the irrigation stream, there is increasing pressure to (1) conserve water in greenhouse operations and (2) avoid contamination of surface- and ground-water supplies by reusing nutrient solutions and runoff water that might otherwise move off the premises.

The City of Fresno, like most of the cities of the San Joaquin Valley, gets its municipal and industrial water from wells that tap the underground reservoir. Pumping over many years has lowered the water level by several feet and has created a cone of depression in ground-water level beneath the city.

The coastal community of Morro Bay, like many other cities in California, is upgrading its sewage treatment plant. As elsewhere, these plant improvements are financed to a large extent with federal and state funds, and a string is attached: Consideration must be given to possible reuse of the treated wastewater or effluent. Morro Bay now disposes of its effluent into the ocean but has the possible alternative of beneficial reuse by piping it inland 1 to 5 miles for irrigation of field and forage crops, under conditions that meet Public Health Department regulations.

Treated wastewater has been used successfully to irrigate forage crops on 1,100 acres in Sonoma County during the past two years. The city of Santa Rosa, with the help of federal and state funding, is delivering effluent to local farmers from a treatment plant with a dry-weather flow of approximately 5.5 million gallons per day.

Food processing in California requires large amounts of water, most of which becomes waste. Since the late 1960s, the major canners, with about 10 plants in the Central Valley, have been irrigating crops with this valuable resource. Many processing plants produce 2 to 4 million gallons per day of effluent during the summer irrigation season. This is sufficient water to irrigate 400 to 800 acres of cropland at each site.

Throughout the agricultural world, the mention of California brings to mind the image of a very rich irrigated agricultural production region. The states rainfed agriculture is often over-looked—probably because the main-stream of travel cuts across the irrigated valleys.

A major pathway of water loss from plants is by transpiration, which accounts for 99 percent of the water taken up by plant roots. This water is lost from the immediate area where the plant is growing, since it passes via the atmosphere to some other point in the hydrologic cycle. Because the water that is transpired is essentially pure, salts in the soil water system become more concentrated.

Many greenhouse growers in the Half Moon Bay area were faced with the need to conserve water in 1976. Because of the drought, growers were limited by the water company to the same amount of water used in 1975. The problem was to cope with an expansion of greenhouse space with no possible increase in water delivery.

Like land plants, aquatic vegetation is a natural and necessary environmental component of the California flora. Aquatic plant species, numbering in the hundreds, occur in impoundments and waterways throughout the state from below sea level to over 6,000 feet.

Energy and water are inextricably linked. It takes immense amounts of energy to pump water and transport it through Californias vast system of canals. Falling water can create large amounts of hydroelectric power, while thermal power plants use large amounts of water for cooling. The economic relationship between water and energy is so close that trade-offs are both unavoidable and highly complex.

The need to use water wisely has been realized in California for decades. Until recent years, however, little attention was paid to another natural resource, energy, and its relationship to water. Since most of California does not receive significant amounts of rain during the growing season, the state depends on the storage of winter rain and the runoff from snow in lakes, reservoirs, and underground aquifers. Very little of Californias vast water storage system could be used if it were not for pumps and the energy they require to move water—and energy costs continue to increase. The study summarized here was undertaken as a first step in understanding the energy requirements for irrigation.