The San Francisco Bay Regional Water Quality Control Board updated its regulations on nutrient discharges into the San Francisco Bay watershed recently to protect the watershed from harmful effects of discharges from municipal wastewater treatment plants and other sources.
Although San Francisco Bay is not impaired by nutrients, it is a nutrient-enriched estuary with higher nitrogen and phosphorus concentrations than most estuaries in the world. Too much nitrogen and phosphorous can lead to harmful algal blooms, which can release toxins to the Bay. Harmful algal blooms can also result in low dissolved oxygen or insufficient oxygen in the water to support aquatic life.
In the Bay, nitrogen has the biggest influence on phytoplankton growth, and the Region’s municipal wastewater treatment plants account for 65 percent of the nitrogen discharged to the Bay. Regional population growth will increase these nitrogen discharges.
The regulatory update, in the form of a reissue of the Nutrients Watershed Permit first adopted in 2014, provides a consistent approach for regulating nutrient discharges from municipal wastewater treatment plants in the San Francisco Bay watershed.
The first Nutrients Watershed Permit required sewage treatment agencies to: (1) monitor their discharges, (2) support scientific studies to evaluate the Bay’s response to current and future nutrient loads, and (3) evaluate opportunities to remove nitrogen through treatment plant improvements. This update will increase monitoring and scientific studies. Importantly, it requires treatment agencies to evaluate opportunities to remove nitrogen using “green” solutions, like routing wastewater through treatment wetlands and wastewater recycling.
These types of opportunities may provide water quality benefits beyond nutrient removal, for example, by providing protection against climate change through carbon sequestration and adaptation of the shoreline to address sea-level rise. Green solutions can also remove additional contaminants of emerging concern for water quality.
Attaining Irrigation Uniformity in Almond Orchards
By Patrick Cavanaugh, Deputy Editor
Terry Prichard, a water management specialist with UC Cooperative Extension at UC Davis for 35 years whe he retired five years ago, is still at work. Prichard is currently collaborating with Almond Board of California to improve water management in almonds, especially irrigation uniformity. “I am still researching nitrogen management for all crops through a grant through the UC from CDFA, and I am helping the Almond Board with their irrigation initiative and their Irrigation Improvement Continuum,” Prichard said.
Prichard explained, “We try to apply water in order to get an average amount of water throughout the field and do that very uniformly. When it is done non-uniformly, farmers are using extra water to reach all parts of the field. So improving irrigation uniformity allows us to apply less total water, but still meet the crop’s water demands,” Prichard noted.
Improvements to irrigation uniformity can be done in any field, according to Prichard. He suggests your designer should strive for good irrigation uniformity when creating your irrigation design. “However,” he clarified, “if you design a less expensive minimal system which uses minimal size piping, you end up using extra energy to drive the pressure through the system to deliver water to the end. Driving that pressure causes friction loss in the pipe—pressure differentials from the top of the system near the pump to the end of the system on the last sprinkler or dripper. These pressure differentials deliver different volumes of water out of each sprinkler, micro-sprinkler or drip emitter, and that is what drives non-uniformity.”
Also important is irrigation maintenance—making sure the system is flushed out and emitters are changed when needed. “Improving uniformity with large orifice-type sprinklers or even larger micro-sprinklers,” stated Prichard, “tends to be a little easier because the holes are larger and don’t plug as easily. In smaller orifice-type systems such as drip irrigation, emitters easily become clogged with physical particulates or biological particulates like slime and algae. Most commonly, lime or manganese forms inside the emitter, clogs it up and reduces the flow, so maintenance of those systems is very important to maximize your designed-in uniformity,” he said.
“Continuum irrigation is an important concept because there is a whole array of current grower practices, some at the minimum level for what we consider for most growers, some are transitioning to more sophisticated methods, and others are already there. I think this continuum will reassure people who are at the minimum level and encourage them to adopt more technological solutions to irrigation scheduling.”
Prichard said the Almond Board’s Almond Irrigation Improvement Continuum doesn’t have a set timeframe. ”It has more accomplishment phases and so what we hope to do is provide each grower with information that they can use on their farm to improve their efficient use of water to produce almonds.”
“And the Almond Board is making these strategies and new technology systems web-based,” noted Prichard. “It is very easy with a web-based system to input new things. The current continuum on the website conceptualizes the basic visual measurements and practices, and you can click on a specific practice for more information on how to incorporate it to accomplish your goals. Then there is a link to a specific discussion such as how to accomplish these efficiencies using drip irrigation, for example,” said Prichard.
”Almond growers have made tremendous strides in improving their efficient use of water, primarily from changing older flood-type irrigation systems to the newer pressure systems. This progress has been tremendous for the industry and for growers in terms of producing more crop using less resources.”
“However, we are now at the next level of using these methods, such as weather-based irrigation scheduling estimates, followed by soil- and plant-based checks, to ensure that you are delivering just the right amount of water,” explained Prichard. “The continuum has generated a lot of grower interest. We have several ways to go and many more tools now than we did ten or twenty years ago.”
Introduced at The Almond Conference in December, the full Irrigation Improvement Continuum and comprehensive background materials will be posted on the Almond Board’s website by March 1, 2016, providing “one-stop shopping” for almond irrigation management at all levels.
According to Almond Board’s January 2016 Outlook newsletter, the continuum describes three proficiency levels and provides a comprehensive program of irrigation management and scheduling practices in five key areas, and also explains how these practices can be effectively integrated at each level. The five key areas include:
Measuring irrigation system performance and efficiency;
Estimating orchard water requirements based on evapotranspiration;
Determining the amount of water applied;
Evaluating soil moisture; and
Evaluating plant water status.
Proficiency level 1.0 (minimum) outlines research-based irrigation management practices that are within reach of all California Almond growers. Proficiency levels 2.0 (intermediate) and 3.0 (advanced) enhance practices to more sophisticated levels to attain even more “crop per drop.”
The goal is to assist all almond growers in meeting level 1.0 proficiency. Beyond this, Almond Board will work with growers to help them progress along the continuum to proficiency levels 2.0 and 3.0, in partnership with technical experts and resources available to California Almond growers, such as through University of California Cooperative Extension.