Posts Tagged: Water

Urban wildfire impacts water, soil and wildlife

UC experts offer tips on testing drinking water, rehabilitating gardens

As residents start to clean up after the Los Angeles County wildfires, the aftermath will continue to impact water and natural resources in and beyond the fire areas, according to water experts at University of California Agriculture and Natural Resources.

Urban wildfires have grown more frequent and intense in the past decade. Record dryness and high winds created conditions capable of enormous heat and destruction; in these types of wildfire events, infrastructure systems – including water supply and electricity – may be affected.

For example, high heat created in urban wildfires can damage or destroy parts of a water distribution system, which disrupts supplies and introduces risks.

“Volatile organics and carcinogens can enter drinking water through compromised parts of the system that get melted by fire,” said Erik Porse, director of the California Institute for Water Resources. He added, “When distribution systems are damaged or face heavy demands, pipes can lose pressure, allowing bacterial growth.”

Water agencies in affected parts of Los Angeles County responded to these risks by monitoring water quality and releasing “do not drink” advisories in affected areas. Such notices are not unusual following disasters, but are jarring for residents who are accustomed to reliable household water. 

Ash, runoff can contaminate supply of drinking water 

If wildfires occur in watersheds that supply cities with water, ash and polluted runoff may contaminate water bodies in fire zones.

“Water treatment systems may be unable to treat incoming water if that water has high levels of solids or contaminants,” Porse said. 

These risks arose with the Hughes Fire near Castaic Lake, which supplies drinking water to parts of northern Los Angeles County. As the fire spread last week, water agencies in Los Angeles were monitoring the situation closely.

Many areas of Los Angeles also rely on groundwater. Future rains can cause contaminants to infiltrate into groundwater basins and create similar treatment challenges for water agencies.

Local water agencies are the best source of information to find out if drinking water is safe. During times of both routine operations and disasters, water utilities are subject to stringent standards and they monitor water quality in their systems as required by law.

“If a water utility publishes ‘do not drink' or ‘boil' advisories in your area, follow directions in the notice and stay up-to-date through website and social media updates,” Porse advised.

Edith de Guzman, UC Cooperative Extension specialist in water equity and adaptation policy at UCLA, added, “Residents who are not in such advisory areas should feel confident that their utility is monitoring the situation and that their water is meeting regulatory standards and is safe.”

Anyone who has concerns about the quality of the water in their home or office can get their water tested. “Water testing can always provide residents or business owners more information and it's important to understand how to interpret results,” said Porse.

Researchers at UC ANR and the Food-Energy-Water Systems for the Underserved lab at UC Merced published a fact sheet with resources on how to test water and understand the results.

Mudslides, degraded waterways other possible effects of wildfires

While rain would reduce overall wildfire risk, as little as a half-inch of rain in a short period of time could also trigger mudslides or debris flows because intense fires alter the ecosystem.

“Mudslides are a danger in areas burned by wildfires because the fires can destroy vegetation that would usually do two things – soak up some of the water and help keep the soil in place,” said Hope Hauptman, assistant project scientist with California Institute for Water Resources. “So, without that stabilizing plant cover, rain can run off quickly, and the exposed soil – particularly on steep slopes – can turn into dangerous mudflows.”

In addition to removing soil-stabilizing plants, intense fires can change soil characteristics, causing it to repel rather than absorb water, said Monica Palta, UC Cooperative Extension specialist in urban water quality, health and justice at UC Irvine.

“A wildfire with high heat can cause sandy soils in particular to become hydrophobic, or repel water,”Palta said. “A hotter fire creates a waxy substance, formed from burned plant material, that coats the soil and inhibits its ability to infiltrate water and elevates surface runoff.”

Elevated surface runoff increases erosion and causes toxic soils and ash to wash into rivers and the ocean.

“Ash from wildfires can contain heavy metals that are toxic to fish and other animals,” Palta said. “Ash from urban wildfires can have additional types of toxins from melted plastics and other materials in human-built structures like houses.”

Wildfire ash also contains large quantities of nutrients like phosphorus and nitrogen. When those nutrients enter coastal waterways, they can trigger harmful algal blooms, which is bad for swimmers, surfers and wildlife. “Algal blooms can produce their own toxins, and the large amount of decomposing algae in an algal bloom consumes oxygen that fish and other aquatic wildlife need to breathe,” Palta explained.

These water quality issues can persist for years after a fire.

“When contaminated water infiltrates soil or is taken up by plants, the contaminants have a good chance of being bound and stored there,” Palta says. “As wildfire destroys plant communities and causes soils to repel water, it causes not only the release of contaminants into the environment, but reduces the ability of an environment to capture and store those contaminants before they reach a river or the ocean.”

Cleanup crucial in rehabilitating garden after fire 

To remove the harmful substances in soil and improve infiltration, Palta recommends taking off the top 6 to 12 inches of soil in gardens, disposing of the soil in plastic bags placed in a trash bin (do not discard in a green bin or compost pile), and then adding new, clean soil to garden beds. 

Mixing in compost also will improve infiltration and bind contaminants like heavy metals. 

“I would advise engaging a professional to remove the soil because you need to wear correct protective equipment to avoid exposure,” she added. “You can wash ash off of garden plants with water from a hose, but be aware that the contaminants will then go into the soil, so wash your plants before removing soil from the yard. Scorched plant material should be removed from the garden, as it may contain contaminants.” 

She also recommends replanting vegetation in the “clean” soil as soon as possible, and taking steps to control erosion. 

“To stabilize slopes and hillsides, you can lay logs or branches perpendicular to the slope to block water and erosion down the slope,” Palta said. 

UC Master Gardeners of Butte County also have a list of tips on how to mitigate damage on a landscape burned by wildfire when heavy rains begin.

The Los Angeles County Department of Public Health encourages testing soil and water (if not done by your local water provider) prior to starting a garden. On page 16 of the agency's Soil and Water Testing Guidelines for Home and Community Gardens is a list of soil-testing labs. 

UCCE offers water measurement training Jan. 30 in Davis

California water-rights holders are required by state law to measure and report the water they divert from surface streams. For people who wish to take the water measurements themselves, the University of California Cooperative Extension is offering in-person training to receive certification on Jan. 30 in Davis.

At the workshop, participants can expect to

• clarify reporting requirements for ranches.
• understand what meters are appropriate for different situations.
• learn how to determine measurement equipment accuracy.
• develop an understanding of measurement weirs.
• learn how to calculate and report volume from flow data.

The training is scheduled for 9 a.m. to 12:30 p.m. on Jan. 30 in the Valley Room at the UC Agriculture and Natural Resources Building at 2801 Second Street, Davis, CA 95616.

“We are limiting the number participants for the water measurement training to 30 people per session,” said Larry Forero, UC Cooperative Extension livestock and natural resources advisor emeritus. “If you need this training, please register soon.” 

Pre-registration is required and the fee is $35. To register, visit https://ucanr.edu/watermeasure. If you have questions, email Forero at lcforero@ucanr.edu or Sara Jaimes at sbjaimes@ucanr.edu or call (530) 224-4900.

Background:

Senate Bill 88 requires that all water right holders who have previously diverted, or intend to divert, more than 10 acre-feet per year (riparian and pre-1914 claims); or who are authorized to divert more than 10 acre-feet per year under a permit, license or registration; to measure and report the water they divert. Regulatory requirements for measurement and reporting are available on the State Water Resources Control Board Reporting and Measurement Regulation webpage. The legislation requires that installation and certification of measurement methods for diversion (or storage) greater than or equal to 100-acre feet annually be approved by an engineer/contractor/professional. 

California Cattlemen's Association worked with Assemblyman Bigelow to allow a self-certification option. Assembly Bill 589, which became law in 2018, allows any water diverter who completes this UC Cooperative Extension course on measurement devices and methods (including passage of a proficiency test) to be considered a qualified individual when installing and maintaining devices or implementing methods of measurement.

Extreme weather accelerates nitrate pollution in groundwater

Extreme weather spurred by climate change, including droughts and heavy rains, may increase the risk of nitrates from fertilizers ending up in groundwater, according to a recent study from researchers at the University of California, Davis. The study found heavy rains after a drought caused nitrates to seep 33 feet under farm fields in as little as 10 days. The study was published in Water Resources Research.

“The conventional wisdom was that it could take several weeks to years for nitrates to move from the crop root zones to reach groundwater,” said corresponding author Isaya Kisekka, a professor in the Departments of Land, Air and Water Resources and Biological and Agricultural Engineering. “We found these extreme events, such as California's atmospheric rivers, are going to move nitrate more quickly.”

In this study, different methods were used to measure how much nitrate, a component of nitrogen fertilizer, was seeping down through the soil in a tomato and cucumber crop near Esparto, California. Scientists conducted their research from 2021 until 2023 when California was experiencing periods of drought followed by atmospheric rivers. They measured nitrate during both the growing seasons and the rainy seasons.

Drought can leave more nitrogen in soil

Previous studies have shown about 40% of nitrogen fertilizer used for vegetables isn't absorbed by the plants but remains in the soil. During droughts, crops don't use nitrogen efficiently, leading to excess nitrogen in the soil. This study found that if a drought is then followed by heavy rainfall, that sudden burst of water causes nitrate to seep in groundwater more quickly. The nitrate concentration in the shallow groundwater exceeded the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water.

“In California, we often say we swing between droughts and floods,” said Kisekka. “These extreme events that come with climate change are going to make the risk of these chemicals ending up in our drinking water much more severe.”

Groundwater is the primary source of drinking water for most of California's Central Valley. In some regions, such as the Tulare Lake Basin, nearly one-third of drinking and irrigation wells exceed the EPA's safe nitrate level. High nitrate levels in drinking water can increase health risks, especially for young children. It may also increase the risk of colorectal cancer.

Need for real-time soil nitrate monitoring

Central Valley farmers are required to report to the Regional Water Board how much nitrogen they applied to their field and how much was removed as part of the crop's yield. The study compared different ways of monitoring when nitrate from fertilizers seep into groundwater. Kisekka said the results highlight the need for affordable, real-time soil nitrate monitoring tools to help farmers manage fertilizer use efficiently.

By using conservation practices that limit leftover nitrates in the crop's root zone after harvest, farmers can help reduce nitrate contamination in groundwater.  

This study's data will also help improve a model called SWAT, which is used to track nitrate seepage into groundwater across California's Central Valley. This effort is part of the Central Valley Water Board's program to regulate irrigated farmlands.

Other UC Davis authors include Iael Raij Hoffman, Thomas Harter and Helen Dahlke.

The study was supported by the USDA Natural Resource Conservation Service through its Conservation Effects Assessment Project. The national project is designed to assess the effectiveness of conservation practices across different watersheds. The study also had support from the USDA National Institute of Food and Agriculture.

Water discussion on Sept. 29 flows from LA art exhibit

Communities in Los Angeles and around California face a variety of water challenges ranging from access to clean, affordable water to water supplies threatened by a changing climate.

The public is invited to a free event featuring a panel discussion of the past, present and future of Los Angeles water. The water discussion will be part of the closing reception for the art exhibit “What's On Tap: LA's Water Story…Source to Spigot” at El Tranquilo Gallery in Los Angeles on Sunday, Sept. 29.

“I hope that people come away understanding that our relationship to and stewardship of water in LA is not only a critical part of our past history, but essential to determining our region's future as well,” said Edith B. de Guzman, UC Cooperative Extension specialist for water equity and adaptation policy with UC Agriculture and Natural Resources and UCLA Luskin Center for Innovation.

The panel will be moderated by UCLA Public Policy Professor Megan Mullin. Panelists will include de Guzman; Amanda Begley, watershed senior program manager for TreePeople; Conner Everts, facilitator for the Environmental Water Caucus, executive director of the Southern California Watershed Alliance, and co-chair of the Desal Response Group; and Mark Gold, director of water scarcity solutions for the Natural Resources Defense Council.

The discussion will be followed by a blind water tasting. Participants will be able to taste how the flavors of three brands of bottled water compare with each other and Los Angeles Department of Water and Power tap water.

“Thus far, many people have chosen LADWP tap as their favorite  compared to the bottled brands,” de Guzman said. “So another hope I have is that people will come away with greater appreciation and trust of tap water.”

The art exhibit, curated by Edith and Jolly de Guzman, highlights five distinct water themes that affect Southern California communities – local water, imported water, tap trust, human right to water and affordability.

The Zanja Madre, a Spanish-era aqueduct that moved water from the Los Angeles River to the pueblo of Los Angeles between 1781 and 1904, once ran past the gallery location.

The “What's On Tap: LA's Water Story…Source to Spigot” exhibit will be open from 11 a.m.-3 p.m. Friday through Sunday, Sept. 27-29, with the closing reception 3-6 p.m. on Sunday, at El Tranquilo Gallery, W-19 Olvera Street, Los Angeles 90012. The panel discussion will begin at 4 p.m. The reception will include live music by Shoshana Ben-Horin.

 

Hands-on learning, training make irrigation best practices accessible

UCCE advisors provide free training to nursery and greenhouse staff

Working as an irrigator seems straightforward at first: if you're not watering plants by hand, you're building and managing systems that can do the watering. What could be complex about a job like this?

University of California Cooperative Extension advisors Bruno Pitton and Gerardo “Gerry” Spinelli can tell you – or better yet, show you.

Pitton and Spinelli, members of the UC Nursery and Floriculture Alliance, offer a one-day technical training in irrigation best-management practices for irrigators working with containerized nursery plants. The comprehensive curriculum – developed with input from two focus groups of California nursery and greenhouse managers – aims to improve irrigation efficiency, reduce water consumption and improve plant health.

Thanks to funding from the California Department of Food and Agriculture, nursery and greenhouse managers in California can request this training for free and advisors like Pitton and Spinelli will travel to conduct the training on-site.

The complexities of irrigation incorporate concepts like evapotranspiration, salinity, irrigation uniformity, capillarity, pressure and flow rate. Spinelli, UCCE production horticulture advisor for San Diego County, said that irrigators have a critical role in the industry because of all the things they must consider to do their job well.

“Our goal is to support irrigators and help them become more confident decision-makers and experts in the field,” said Pitton, UCCE environmental horticulture advisor for Placer and Nevada counties.

Interactive sessions reveal nuances of irrigation

The training consists of a presentation on fundamental concepts for managing irrigation in container plant production and hands-on demonstrations. “In the nursery industry, where precise irrigation is crucial for the health and productivity of our crops, having access to expert knowledge is invaluable,” said Mauricio de Almeida, general manager of Burchell Nursery in Fresno County. “The training's practical demonstrations and real-world examples made the concepts easy to grasp, allowing our team to implement the strategies immediately.”

For one of the demonstrations, the advisors used sponges to model soil saturation when water is applied. Ana, an irrigator at Burchell Nursery, appreciated the step-by-step explanations, which helped her better understand how water pressure differs in drip irrigation, sprinklers and watering by hand. Doing this out in the field, as an example of how irrigation audits occur, was extremely helpful for attendees.

Francisco “Frank” Anguiano, production manager of Boething Treeland Farms in Ventura County, observed his team of irrigators as they learned how to measure distribution uniformity with water collected from sprinklers. “This training isn't just about irrigation and plant management. It's also about savings, both water and costs. Who doesn't want to save money and use less water?” Anguiano said.

Reducing the barriers to learning

Many of the irrigators attending these trainings gained their skills and knowledge from life experience rather than a college education, explained Peter van Horenbeeck, vice president of Boething Treeland Farms. “It's important that my irrigators learn from external experts, but it's more important that they can relate to them. And that's what Gerry was able to do,” van Horenbeeck added.

Regarding content and delivery, and referencing what he learned from the focus groups, Pitton wanted the trainings to be easy to understand and engaging. For example, scientists use the term “matric potential” to describe how soil particles hold water against gravity, which is the same as capillary rise. “We demonstrate this concept with a paper towel held vertically and dipped into a beaker of dyed water that it absorbs,” said Pitton.

Many of the irrigators in attendance agreed that hands-on activities and visual aids were instrumental to their learning. Charli, another irrigator at Burchell Nursery, shared that the in-field examples and hosting the training in Spanish kept them engaged.To address language barriers, Spinelli has been conducting trainings in Spanish – a common request from many nurseries with eager participants.

Maintaining state regulations and partnerships

Although the technical aspects of irrigation management are key elements of the training, regulatory compliance is also addressed. Recognizing the finite availability of water and the environmental impact of pollution, the advisors highlight irrigation and fertilizer management and runoff prevention as critical components of compliance.

Under Ag Order 4.0 administered by California's Water Resources Control Board, growers must comply with stricter policies regulating nitrogen use. As irrigators learn from the training, better control of irrigation can certainly make a difference.

Deanna van Klaveren, chief operating officer and co-owner of Generation Growers in Stanislaus County, said the most valuable aspect of the training was learning on-site and completing an audit on her own systems. “It is so much more impactful to have trainings like this on-site where our staff can learn and then go out into the nursery and actually put it into practice while the presenters/experts are there,” van Klaveren said.

Pitton and Spinelli described the partnership between UC Cooperative Extension and CDFA as “symbiotic” given the technical and educational capacity of UCCE advisors who conduct research and extension.

“It's a great example of how the two institutions can collaborate successfully. Californians are the ones who win because they get a service for free,” added Spinelli. “And it's rewarding for us to see so much interest in what we, as advisors, do.”

If you are a nursery or greenhouse operator and would like to request the Irrigation Best Management Practices training, please contact the UCCE advisor assigned to the region that corresponds with your nursery location below.

Northern California

• Jessie Godfrey, UCCE environmental horticulture and water resources management advisor, jmgodfrey@ucanr.edu

Central Coast (Santa Cruz County to Ventura County)

• Emma Volk, UCCE production horticulture advisor, evolk@ucanr.edu

San Joaquin Valley

• Chris Shogren, UCCE environmental horticulture advisor, cjshogren@ucanr.edu

Southern California

• Grant Johnson, UCCE urban agriculture technology advisor, gejohnson@ucanr.edu

Spanish Trainings Only

• Gerry Spinelli, UCCE production horticulture advisor, gspinelli@ucanr.edu

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