As the drought lingers in California, and concerns about how to save water are at the forefront of our minds, many of us are thinking about how we can best conserve water in the garden.
Where do we get our water?
Water conservation is of utmost importance these days. Our rivers and lakes are depleted, and the water sources for our major cities and agricultural areas are running dry. But where does the water from our tap come from, and why is it running low? In the East Bay, our water supply comes from captured snowmelt from undeveloped public and private watershed lands of the Mokelumne River. It is collected at the Pardee Reservoir which is 90 miles east of the Bay Area.
“In a year of normal precipitation, EBMUD uses an average of 21 million gallons per day (MGD) of water from local watershed runoff.”
In drought years, most, if not all, of the snowmelt runoff is evaporating from the reservoir, so what we have historically counted on to replenish the water supply in the reservoir is disappearing. Without the annual replenishment of water to make up for what is used, the water stores become depleted. This is why there are alarm bells raised for us to conserve water in our homes by up to 30%. As the planet gets hotter and drier, our water stores are going to continue to diminish more over time.
There are many ways we can work together to bring down our water usage. Here are a few tips on how to save water in the home from the State Water Resources Control Board. Many of these tips, such as take 5 minute showers and turning off the water when you brush your teeth or shave can save a significant amount of water.
Even today, the overall square footage of most gardens are made up of a conventional lawn. Due to the high water usage of lawns, and because lawns are typically irrigated with sprayers that lose up to 75% of the water they put out in evaporation, they are water guzzlers, and need to go. One of the main ways our municipalities are asking us to conserve water is by restricting the amount of water we use in the garden. Currently, in the East Bay, we are limited to watering our gardens 3 times per week. For many of our established Mariposa Gardens, this works out fine. We have conditioned the soil, installed a Netafim drip irrigation system, a subterranean line that loses no water to evaporation. However, under watering a healthy native low use garden can have more damaging effects on climate change than it would cost to give that garden the right amount of water to thrive.
It's all about the soil
The Mariposa garden care team consistently checks the soil to make sure that the soils in our gardens have a very consistent saturation level to that of a wrung out sponge. When soils dry out due to heat spells, or after our long dry summers, they can become hydrophobic. Hydrophobic soils are like a dried out sponge. Water will be dripped into the soil and will bead off and roll down, not allowing its life giving sustenance to the plant roots. This can happen, even in an established garden under high heat conditions, especially on sunny and exposed slopes. Once the soils become hydrophobic, it takes a lot more water to rehydrate the soil so that it gets to the saturation point of a wrung out sponge. This saturation point in the soil acts just like a sponge does. It will take that drop of water, and wick it through the soil, thereby keeping your plant roots well hydrated. Well hydrated plants are healthier, are better able to resist disease and pests and also contribute to transpiration. It is the transpiration of plants that creates clouds, and rain. Therefore, we are under an ecological obligation to keep our gardens hydrated.
It’s important to understand that green, growing things (plants) provide a critical role in supporting the earth’s water cycle. Reducing water use by allowing our gardens to dry out and die back will only escalate our drought problems.
Transpiration is the movement of water through plant leaves, stems, and flowers into the atmosphere where moisture condenses and contributes to precipitation that falls from the sky and back into the soil. And then the cycle repeats. Less rain means less access to naturally clean water. And in the absence of a thriving layer of plants, any water captured in the soil moves further down into the ground, where it can be stored for thousands of years. Without plant cover, transpiration is reduced, in effect robbing the water cycle of potential moisture. A loss of green plants will increasingly heat up the planet and dry it out.
How do we Conserve Water?
At Mariposa, we have worked hard to find ways that we can both conserve water and keep our gardens lush and full of plant life that will contribute to the cooling of the planet. Sometimes this means that during hot spells, we may need to water our gardens in areas that are more exposed to the sun and heat more than 3 days per week. This does not mean the gardens need to over consume water, but allowing the soil to become hydrophobic is a bigger contributor to global warming than adding more water to the garden. We want to help our clients to find the balance between water conservation and keeping the gardens green.
One of the ways that we do this is through water harvesting. In all of our garden designs, we are incorporating ways to keep the water that falls on your property there. We will take your downspout and direct the water that falls onto the roof and slow it, sink it and spread it out into the garden. This helps to raise the groundwater table on your property, which can help larger plants such as trees and shrubs have better access to water during drought periods.
Another way we do this is by tapping into your graywater, and developing a greywater system that will keep your plants green. There are many ways to design a greywater system. One of our specialties at Mariposa is our Living Fountain. The Living Fountain cycles your graywater through a mini constructed wetland system. The water is filtered through plant roots and soil, nature's way of cleaning water, which is superior to any constructed water filtration systems. In addition to cleaning the water, it is also bio-activated with beneficial nutrients and bacteria which act to help your plants thrive, and become more drought tolerant.
Andrea Hurd, founder of Mariposa Gardening & Design.