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Fruit trees, especially citrus, thrive in San Diego County’s climates with just a little bit of care. The Pineapple Guava (Acca sellowiana) is a good choice with spectacular blooms. Photo: WIkimedia/Creative Commons License Edible Plants climate zone

Sustainable Gardeners, Get Into Your Climate Zone

People around the world know San Diego for its beautiful, sunny, and mild weather. San Diego residents know our daily weather has more variety than visitors might imagine.

Climate is defined as the average weather conditions in an area over a long period, generally 30 years or more. German climate scientist Wladimir Koppen first divided the world’s climate into six regions in the early 1900s.

Since then, U.S. climate zones have been defined in more detail. The U.S. Department of Agriculture defines climate zones according to the lowest average temperature in the region. You may also be familiar with the 24 climate zones identified in Sunset Magazine’s iconic Sunset Western Garden Book. The book is now out of print, but is available online as an interactive edition. Existing print copies from the last edition printed in 2012 are prized heirlooms.

Devoted gardeners still follow the 24 climate zones featured in the guide. This is based on the California Irrigation Management Information System (CIMIS) adoption of a similar map identifying 24 climate zones.

San Diego County's geography falls within six of the 24 CIMIS climate zones. Photo: CIMIS match your climate zone

San Diego County’s geography falls within six of the 24 CIMIS climate zones. Photo: CIMIS

Evaporation + Transpiration = Evapotranspiration

Depending on the amount of rainfall, temperature, humidity, wind, shade, and the nature of the soil, water in the ground evaporates at different rates. When evaporation is higher, the soil becomes dry more quickly.

Evapotranspiration (ET) is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces, and by transpiration from plants.

Reference Evapotranspiration (ETo) is a baseline formula. All your plant water needs are measured against this baseline in a complex series of measurements and calculations.

Why is understanding evapotranspiration important?

In metropolitan San Diego County, our annual ETo rate increases as you move inland, meaning the soil becomes dry more quickly.

Fortunately, we don’t need to worry about making these calculations on our own. CIMIS maintains a statewide system of weather stations and reference plots. From these, it has identified the six main ET Zones in San Diego County.

Understanding your ETo zone and gardening climate zone are important first steps toward deciding how much water your landscaping will need. Working against the ETo and gardening climate zones can greatly increase your need for irrigation.

Learn more about your ETo climate zone’s specifics and gardening microclimate on the California Irrigation Management Information System website.

 

This article is part of a year-long series inspired by the 71-page Sustainable Landscapes Program guidebook available at SustainableLandscapesSD.org. The Water Authority and its partners also offer other great resources for landscaping upgrades, including free WaterSmart classes at WaterSmartSD.org.

Pendulum Swings in Clean Water Act Regulation

The regulatory pendulum is expected to swing toward stricter Clean Water Act enforcement, though experts say the Biden administration’s changes probably won’t be immediate. Farmers and environmentalists have been in a political tug-of-war over the law’s scope for years, largely due to ambiguous legal interpretations of the statute. While Democrats will now have power over Congress, their majority is too slim to make changes to the law, said Don Parrish, the American Farm Bureau Federation’s senior director of regulatory relations.

Opinion: 3 Critical Lessons California Offers to Improve Restoration of Land On a Global Scale

2021 presents opportunities for decisive and positive action, including the launch of the United Nations’ Decade on Ecosystem Restoration which reinforces the importance of healing degraded ecosystems around the world before it’s too late.  It gives us great hope to know that California is committed to leadership through investment and sharing lessons learned from decades of experience. Our diverse ecosystems, abundant natural resources and a mild climate have helped attract millions of residents and developed California’s world-class economy.

Sunlight Powers Portable, Inexpensive Systems to Produce Drinking Water

In an increasingly hot and crowded world, clean water is becoming a precious commodity. Two thirds of the global population will have problems accessing fresh water by 2025, and removing salt and contaminants from the oceans and groundwater is one way to slake humanity’s thirst. Today’s large desalination plants, though, cost millions of dollars to build. Most use reverse osmosis, which forces seawater through salt-blocking membranes.

Ramona Water District Digs Into Roads for Pipe Repairs After County Has Paved Them

A labyrinth of aging water pipes is putting the Ramona Municipal Water District on the hook for the costs of repairing water leaks and conducting emergency repairs on water mains, which are among the district’s primary responsibilities, but also for costs related to repaving roads after the pipe work is completed.

Valley Groundwater May Get (Small) Slice of State’s $15 Billion Surplus

The Governor’s proposal for how to spend California’s $15 billion surplus includes $60 million in direct grants to help replenish groundwater in the valley’s most depleted basins.

The measure specifies the money is to be used in “critically over-drafted basins,” which lie mostly in the San Joaquin Valley.

Gary Croucher-Board Chair-San Diego County Water Authority-Primary

Building a Collaborative Vision for San Diego County

We welcome the new year with heavy hearts about the recent events in our nation’s Capitol and a renewed commitment to civility and respect at every level of government.

At the same time, we are maintaining our concentration on our priorities for the year, which are numerous and significant. I’m focused on advancing San Diego County’s interests as we continue to fulfill our mission of making sure that our region has safe and reliable water supplies at an affordable price, which is critical to maintaining our economic competitiveness and sustaining our wonderful quality of life.

Here’s some good news about how the Water Authority is putting San Diego County first in 2021:

  • As part of our commitment to meeting some of the strictest environmental regulations in the world, the Water Authority and Poseidon Water have launched a state-of-the-art project evaluating intake screen technologies at the Claude “Bud” Lewis Desalination Plant, which has served more than 65 billion gallons of locally produced water over the past five years. Crews are testing both active screen and passive screen technologies in Agua Hedionda Lagoon to complete the full-scale project by the end of 2023.
  • We are updating our Urban Water Management Plan, which is a critical part of meeting the long-range water needs of the San Diego region for both normal years and dry years. This planning document is increasingly important given the increasingly unpredictable impact of climate change. The planning process is, of course, a collaborative effort with our 24 member agencies as we account for their local supplies and demand projections.
  • Our low-cost supplies of conserved water from the Imperial Valley are the foundation of our diversified supply portfolio. With Board direction, staff has launched the next phase of a study to explore a new system to deliver those supplies because initial studies show it could be most cost-effective than the current system and mutually beneficial for our partners in the valley. The study will only advance if it benefits the region by providing cost savings for ratepayers.
  • As the regional economy recovers, we are working hard to protect ratepayers by maintaining a focused and strategic budget. It’s a tough balance, but we are working hard to find the right combination of near-term and long-term funding priorities in these challenging times.
While I’m glad to put the old year behind us and welcome 2021, I’m certain there will be many challenges and opportunities ahead. I’m committed to keeping you informed along the way, and to working with our Board, member agencies, stakeholders, regional leaders and ratepayers to create innovative solutions. In my 20-plus years on the Water Authority Board, we’ve never shied away from big and bold ideas – and 2021 will be no exception.

Helix Water District Reduces Plant Upgrade Costs

When the Helix Water District received contractor estimates as high as $3.5 million to upgrade the R.M. Levy Water Treatment Plant’s ozone power supply units and generators, it decided to perform the upgrade in-house.

With Suez Water Technologies provided engineering and equipment, Helix employees incorporated new technology and innovative installation practices. The proof of concept pilot project proved the feasibility of the new approach, and a full retrofit is now planned. The estimated upgrade costs to complete the full project is $1.1 million – an approximately 70% cost savings. The upgrade will extend the life of the power supply units and generators at least 15 years.

Valve Opening Sends Billions of Gallons of Water From Loveland to Sweetwater Reservoir

A valve at the base of the Loveland Dam near Alpine was opened Monday, allowing billions of gallons of water to thunder down the valley toward Sweetwater Reservoir in Spring Valley. “It’s a spectacle that is hard to forget,” said Hector Martinez, Chairman of the Sweetwater Authority “Very powerful! I almost feel the ground shaking when the water is being released.” The gushing valve is a sight to behold, and thanks to the massive transfer, South Bay water customers might be looking at their water bills with similar amazement.

Drought-Stricken Colorado River Basin Could See Additional 20% Drop in Water Flow by 2050

Colorado is no stranger to drought. The current one is closing in on 20 years, and a rainy or snowy season here and there won’t change the trajectory. This is what climate change has brought. “Aridification” is what Bradley Udall formally calls the situation in the western U.S. But perhaps more accurately, he calls it hot drought – heat-induced lack of water due to climate change. That was the core of research released in 2017 by Udall, a senior climate and water scientist at Colorado State University’s Colorado Water Center, and Jonathan Overpeck at the University of Michigan.