- Author: Glen Martin
Reprinted from California Magazine
With perhaps one of the most intense El Niño ever recorded simmering like a massive coddled egg off the coast, Californians are bracing for precipitation on an epic scale. More than that: They're hoping for it. There is a general sense that even the rampaging floods that can result from a full-blown El Niño-driven winter would be tolerable as long as our reservoirs fill and aquifers recharge and we can get back to long showers and adequately watered hydrangeas.
This is a good place to insert a couple of caveats. First, choose your wishes carefully. Recall, if you were in California at the time, the great El Niño of 1997-98, and the vivid images it provided of nature running amok: Highway 70 disappearing into the vast, churning inland sea that was once the Yuba River, with dead cows, outbuildings and giant hissing propane tanks bobbing downstream. That was the year the dikes failed on the Feather River, and thousands of Yuba City residents fled the rising waters. After it was all over, one staffer with the U.S. Army Corps of Engineers chatted off the record, and said there had been very real fears that Folsom reservoir could have overtopped its dam. If that had happened, much of Sacramento would have flooded. People would have died. Four years of drought may have made people forget that California can be blighted by too much water as well as too little.
Second, observes Doug Parker, the director of UC's California Institute for Water Resources, the rain and snow may fizzle. A robust El Niño is no guarantee of record rainfall and snowpack.
“In fact, the research indicates a wet year for Southern California, but there's less confidence about a lot of precipitation for the north state, particularly in terms of snow,” says Parker.
And we need snow more than we need rain. Parker notes that intense rainfall can produce too much water too fast at the lower elevations and melt snow at the higher elevations. In such cases, the state's dams and reservoirs have to function as flood control structures; much or most of the water is shunted rapidly to the sea, not stored.
One wet winter could put a lot of water in our reservoirs and maybe help replenish some aquifers, but it will do nothing to address demand.
Further, cautions Parker, even an optimal El Niño that dumps heaps of snow in the Sierra without swamping the lowlands with Pineapple Express deluges may not get us back to “normal.” That's because surface water is only part of the issue. Brimming reservoirs alone cannot slake the state's thirst. According to theCalifornia Department of Water Resources, groundwater constitutes between 30 to 46 percent of the state's total water supply. Despite recent legislation to monitor and control groundwater withdrawals, pumping remains largely unregulated, and many of the state's aquifers are in “overdraft,” with more water being sucked up and out than trickling back underground. The results of this excessive pumping are particularly evident in the San Joaquin Valley, where massive ground subsidence—a sudden sinking or gradual sinking of the Earth's surface— is occurring as groundwater is withdrawn.
These effects are not temporary. Ground subsidence can destroy aquifer structure, reducing long-term storage capacity. And while heavy rains and deep snowpack are essential for recharging aquifers, the process isn't necessarily a rapid one.
“There are some areas where recharge happens fairly quickly, particularly if combined with decreased pumping,” Parker says. “But other areas may require decades or centuries to replenish. Also, you have to consider what you mean when you say ‘recharge.' In the Tulare Basin, the water table has fallen by hundreds of feet, it keeps dropping, and the pumping continues. So what does ‘recharge' mean? Getting water back up to 300 feet from 400 feet? What's your baseline? When water is that deep, it's unlikely you could get any significant or long-term replenishment from one year, especially considering the ongoing demand.”
And that may well be the ultimate rub: Demand. The problem with a state that has so many people and so much intensive agriculture is that water demand is by no means static. It's constantly moving, but it only moves one way: upward. No matter how much water we get, there will always be someone clamoring for it. Water rights claims exceed the amount of the state's developed water—the water controlled and distributed by government agencies—by 5.5 times. Even during the last four years of devastating drought, thousands of acres of new almond orchards have been planted in the Sacramento and San Joaquin Valleys, and almonds are a water-intensive crop, each tree requiring heavy irrigation for its entire productive span.
“One wet winter could put a lot of water in our reservoirs and maybe help replenish some aquifers, but it will do nothing to address demand,” says Parker, “so ‘getting back to normal' doesn't really speak to the biggest issues. People will always have a use for any water that's available. If we want a truly sustainable water policy, we can't be reactionary. We can't look at this from the perspective of one year, or a few years. We have to take a long-term view.”
In a recent forecast, the National Weather Service said Northern California stands a decent chance of getting significant rain from this winter's El Niño weather pattern. The bulk of the precipitation will fall in December, January and February. If you haven't already done so, it's time to start preparing for El Niño. Here are 10 steps to take:
Clean up your yard.Inspect your landscape for debris, outdoor furniture or other objects that could be tossed by storm winds. Spend an afternoon tidying up the yard and storing or securing furniture and other loose items to prevent a frantic scramble to collect items that have landed on your roof or in your neighbor's yards.
Inspect gutters and downspouts. Make sure gutters are clear of leaves and other debris and connections between gutters and downspouts are functioning properly. Faulty gutters and downspouts can also lead to soil erosion adjacent to buildings and serious water and foundation displacement problems in basements and crawl spaces. Make sure downspouts direct water away from buildings and do not create standing water. Storm water runoff from impermeable surfaces (roofs, driveways, patios) should be directed into a collection system to avoid soil saturation.
Inspect your roof. Roofs with loose tiles or holes spell trouble. Inspect flashing to ensure water is directed away from seams and joints.
Inspect retaining walls. Check retaining wall drains, surface drains, culverts and ditches for obstructions or other signs of malfunction. Do this review before the storm season and after every storm.
Inspect slopes. Monitor sloped areas for signs of gullying, surface cracks and slumping. Inspect patios, retaining walls and garden walls for signs of cracking or rotation, which might indicate slope movement. If you notice problems, have the site inspected by a geotechnical engineer.
Vanquish bare ground. Make sure your yard and garden does not have bare areas that could initiate mudflows during a storm. Fall is a good time to put down mulch and establish native plants. There may still be time to encourage vegetation in bare areas before the storm season.
Review storm drains.Inspect storm drains before the storm season and after every rain. If drains are obstructed, clear the material from the drain or notify the Department of Public Works or the public agency responsible for drain maintenance.
Monitor trees.If any trees appear weakened by drought, ask an arborist to inspect them. High winds can fell trees, and their branches can knock out power or seriously damage homes and vehicles.
Install swales and French drains. If you have areas that flood, consider installing swales or French drains to move the water to where it can better infiltrate the soil. Swales slow and capture runoff by spreading it horizontally across the landscape. Create a swale by digging a ditch on contour and piling the dirt on the downhill side of the ditch to create a berm.
A French drain is a trench filled with gravel or rock containing a perforated pipe that redirects surface water and groundwater away from an area. A French drain can have perforated hollow pipes along the bottom to quickly vent water that seeps down through the upper gravel or rock. French drains are primarily used to prevent ground and surface water from penetrating or damaging building foundations.
Consider further steps. If you still have concerns about slope stability, flooding and mudflows after taking these steps, consider stockpiling sandbags and plastic sheeting, straw wattles or straw bales. These items can form a barrier to keep water from flooding low areas. Plastic sheeting can be placed on slopes and secured with sandbags to prevent water from eroding the soil.
Workshop: U. C. Master Gardeners of Napa County will host a workshop on El Niño on Saturday, October 31, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension Office (address below). An El Niño winter is on the horizon, no doubt about it. Napa County could well see heavier than average rainfall. This workshop will focus on measures to take now to prepare your home and garden for heavy rain. You will also learn steps to take during and after a flood. Online registration (credit card only) Mail-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
During the winter of 2014, which was extremely dry and cold, I lost my sweet little young Meyer lemon. I was flummoxed as to the reason. Yes, I had listened to the frost predictions and conscientiously covered the tree during the nights the low temperatures were predicted. Yes, I had augmented this arrangement with outdoor-certified extension cords and flood lights to create heat.
When the sun came up in the morning, I removed the coverings and turned off the lights to allow the tree and the soil beneath it to absorb as much daylight and ambient daytime heat as they could. What had I done wrong?
My poor tree was so stressed from lack of water that it didn't stand a chance. I had stopped irrigating in November and never gave it a second thought. But think back to that winter. We had very light precipitation and frequent frosts. Being a baby, the tree had no reserves.Faced with the lack of water and the cold, it could not cope.
I have since decided that the tree's location was not the optimum choice. Napa Valley is blessed with a mediterranean climate, characterized by mild, wet winters; mostly prevailing westerly winds; and warm, dry summers. Coupled with the many micro-climates in our gardens, this weather allows us some options for placing citrus trees.
Microclimates are the distinctive climates zones within your garden. At the end of a hot day, walk around your garden after the sun has gone down. I did this recently when I took the dog out late at night. As I walked by the west-facing side of our stucco house at midnight, the day's heat was still radiating off of it. Any frost-sensitive citrus tree would love living there. So choose a west- or south-facing location, preferably against a wall or fence that will capture and return the daytime heat.
Frost protection is a major issue with citrus. Stay informed about the weather and be prepared. Keep tender plants hydrated, and keep the area beneath your citrus trees' canopies free of mulch or any cover. This will allow the soil to absorb heat during the day, and after the sun goes down, the rising heat will warm the trees.
Cover your citrus when frost threatens to protect delicate foliage. The entire neighborhood gets to see my taste in linens because I use old sheets, but a cloth tarp works, too. Plastic isn't recommended as it does not breathe. Try to keep the cover off of the foliage by draping it over some kind of structure. If the cover touches foliage, those leaves may freeze. Uncover when the sun comes up.
Christmas tree lights (the old-fashioned type, not LED) can add a few degrees of protection. Drape them around the trunk and branches, or place a large spotlight on the ground under the cover. Use only outdoor-rated lighting and cords.
Citrus have shallow roots that are easily damaged, so plant them where the soil does not get disturbed. Monitor soil moisture even in winter. Don't allow container-grown trees to dry out completely.
Consider growing citrus in containers to have more location options. You can put wheels on the pot and position the tree in your best location to take advantage of microclimates. Container-grown citrus needs to be transplanted every three to four years and monitored closely for nutrient deficiencies.
Choose the citrus varieties best suited to your area. Check for pests frequently. Feed regularly to keep the foliage green and the fruit coming, especially with young trees.
Fifteen years ago, the citrus leaf miner turned up in California citrus. Recently,citrus greening disease has become a huge concern for California growers. Be aware of these pests and diseases and be proactive in caring for your trees. For more information, consult the University of California Agriculture and Natural Resources web page (www.ucanr.edu), using the key phrase “citrus.”
Workshop: U. C. Master Gardeners of Napa County will host a workshop on citrus on Saturday, October 24, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension Office (address below). This workshop will focus exclusively on caring for citrus, large and small. Potting and repotting container citrus, pruning, watering and fertilizing, frost protection and recovery from frost damage are part of the program. The workshop will also cover using the University of California IPM website to identify and understand citrus diseases and pests. Online registration (credit card only); Mail-in registration (cash or check only).
Workshop: U. C. Master Gardeners of Napa County will host a workshop on El Niño on Saturday, October 31, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension Office (address below). An El Niño winter is on the horizon, no doubt about it. Napa County could well see heavier than average rainfall. This workshop will focus on measures to take now to prepare your home and garden for heavy rain. You will also learn steps to take during and after a flood.Online registration (credit card only)Mail-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
- Author: Ben Faber
Oh, oh is there going to be a wet fall and winter? If it comes and washes the accumulated salts of the last four years out of the root zones of citrus and avocado, that's a good thing. But what happens if there is a little too much of the good stuff? In the winter of 2005, Venture got over 40” of rain, which is 200% of what is normal. The last time big rains occurred prior to that was in the winter of 1997-98. That year the rains were evenly spaced on almost a weekly basis through the winter and into the late spring and over 50" fell. That year we had major problems with both citrus and avocados collapsing from asphyxiation. The same occurred in 2005, but not so pronounced. This winter could also see some collapse.
Asphyxiation is a physiological problem that may affect certain branches, whole limbs or the entire tree. Leaves wilt and may fall, the fruit withers and drops and the branches die back to a greater or lesser extent. The condition develops so rapidly that it may be regarded as a form of collapse. Usually, the larger stems and branches remain alive, and after a time, vigorous new growth is put out so that the tree tends to recover.
Asphyxiation is related to the air and water conditions of the soil. The trouble appears mainly in fine-textured or shallow soils with impervious sub-soils. In 1997-98, this even occurred on slopes with normally good drainage because the rains were so frequent. When such soils are over-irrigated or wetted by rains, the water displaces the soil oxygen. The smaller roots die when deprived of oxygen. When the stress of water shortage develops, the impaired roots are unable to supply water to the leaves rapidly enough and the tree collapses. The condition is accentuated when rainy weather is followed by winds or warm conditions.
Canopy treatment in less severe instances consists of cutting back the dead branches to live wood. If leaf drop has been excessive, the tree should be whitewashed to prevent sunburn. Fruit, if mature should be harvested as soon as possible to prevent loss. In the case of young trees, less than two years of age, recovery sometimes does not occur, and replanting should be considered if vigorous regrowth does not occur by July.
Asphyxiation can be reduced by proper planting and grading. If an impervious layer is identified, it should be ripped prior to planting. The field should be graded so that water has somewhere to run off the field during high rainfall years. Heavier soils might require planting on berms or mounds so that the crown roots have a better chance of being aerated.
Post-plant, if an impervious layer can be identified and is shallow enough to break through, ripping alongside the tree or drilling 4-6 inch post holes at the corners of the tree can improve drainage. It is important that the ripper blade or auger gets below the impervious layer for this technique to be effective.
We don't know what the future holds. Hopefully rain that does some good without too much harm.
Avocado asphyxiation 2005
For the Napa Valley, El Niño refers to a weather pattern in which warming sea surfaces cause heavier-than-average winter rains and wind with warmer-than-normal temperatures.The U.S. Climate Prediction Centerhas predicted 65 percent likelihood that we will feel the effects of El Niño as summer ends, with that probability rising to nearly 80 percent by the end of the year. The National Oceanic and Atmospheric Administration says that this weather pattern usually continues for nine to twelve months.
Because of the current drought, the idea of a wet winter is welcome to me. The coming rains are too late for a number of my trees and shrubs, which are either dead or have dead branches. And the high winds that accompany El Niño storms could blow any of these trees down. Clearly I need to trim dead branches and trees and make sure weak plants are staked properly.
El Niño storms often dump massive amounts of rain in a short time, creating flash floods and heavy water build-up in yards. You can find some good suggestions on how to handle storm water as well as how to collect it for future use at www.countyofnapa.org. In the search box, type “slow it spread it sink it” to find an online reference guide by that name.
Since good drainage is extremely important to plant health, my other pre-storm chores involve clearing a place for the rain water to go. These tasks include clearing weeds from the run-off ditches in my yard as well as cleaning out rain gutters and spouts.
Highly saturated soils make it hard for plants to survive. In wet soil, t is almost impossible for roots to take up all the oxygen that the plant needs, which causes the roots to decay. Deep roots are the first to rot. If the condition continues shallower roots will also be damaged. Even plants that don't appear to be flooded may have problems during extended wet weather. And you may not see the damage until next summer. One of the best defenses for your winter vegetable garden is to make sure you have well-drained soil and to plant in mounds.
After an El Niño season, everything may appear normal in your garden until summer temperatures top 90°F. After the 1997-98 El Niño season, Napa County farm advisor Dean Donaldson warned Master Gardeners about this phenomenon in the group's newsletter. “Sometimes tree growth is simply stunted,” wrote Donaldson. “Usually, however, people observe their beautiful trees and shrubs suddenly turning from green to yellow or reddish brown. Usually it is the entire tree and it happens within a few days of hot weather. Insects are attracted to those weakened trees and often get the blame. If the whole tree dies, you can blame El Niño.”
When those record-breaking El Niño rains subsided and weather warmed up, fungal and bacterial pathogens emerged on foliage. Many trees and shrubs evidenced phytophthora root and crown rot. Slime molds appeared on soil surfaces, and snails and slugs proliferated.
Anthracnose, fire blight, and powdery mildew all thrive after a mild, wet spring. When you see evidence of these diseases on plants, cut out and discard the affected material immediately. Sanitation is the number-one way to keep these diseases from spreading. Iron chlorosis may also be a problem in wet soils.
The best thing we can do for our gardens before an El Niño-influenced winter is to create good drainage. Afterward, watch for symptoms of root rot, fungus or bacterial diseases.
Garden Tour:The UC Master Gardeners of Napa County invite you to their sixth garden tour, “Down the Garden Path,” on Sunday, September 13. On this self-guided educational tour you will see seven gardens by Master Gardeners in and around the City of Napa. These gardens illustrate how Napa County Master Gardeners use University of California research-based horticultural information to develop and maintain their own gardens.
Tickets: $30 Advance/ $35 Day of Event. Purchase tickets at http://ucanr.edu/ucmgnapa. Or you can purchase tickets at the UC Master Gardener office (address below). For more information, call 707-253-4143.
Workshop: The UC Master Gardeners of Napa County will host a free workshop on “Worm Composting” on Saturday, September 26, from 9 a.m. to 11 a.m., at the Napa Valley Museum, 55 Presidents Circle, Yountville. Explore worm composting, an ideal solution for composting kitchen scraps and returning the nutrients to your soil, especially when outdoor space is limited. Co-sponsored by Napa Recycles! Free Online Registration.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.org/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.