March 18, 2017
As Coleridge said “water, water everywhere, nor any drop to drink.” This, of course, refers to salt water. But California has certainly had more than its share of fresh water falling from the skies this winter and we do have plenty to drink, fortunately. But does this drought-busting rainfall allow us to freely turn on the taps? Not really.
First a little about water itself. Water has the amazing and unique property of existing as a solid, liquid or gas in nature. And there’s a lot of it all around us. Amazingly, we know there are 326 million trillion gallons of water on earth and that only 2.5 percent of all of this water is fresh, with two-thirds of it currently locked up in ice caps and glaciers. Another 21 percent is found in lakes. Rivers, which feed the lakes, account for a tiny fraction, 0.49 percent of fresh water, but humans get a large portion of their water from rivers.
Our bodies are 60 percent water and we can only survive 3 to 10 days without this life-giving substance. Plants are 90 percent water and water enables photosynthesis to happen, without which all life would cease. Water has existed on Earth since before the sun formed and as it moves through the water cycle from evaporation off the ocean, to rain and snow, runoff back into the ocean, we drink that water over and over again, the same water that has existed since the beginning of Mother Earth. Awesome, isn’t it?
Marin isn’t in a drought, but some parts of the state still are. This doesn’t mean that we don’t need to conserve any more because we need to treat water like the precious resource it is. Annoying as it is, I’m still saving the 2 gallons of water it takes to get hot water to my shower, which I pour into the washing machine or use to water houseplants.
What’s the likely fallout of all this rain? Recently I heard Steven Swain, the UC Cooperative Extension environmental horticulture advisor, talk about erosion. He pointed out that when our hillsides were covered with perennial native grasses they had the ability to hold more water than they do now, covered with annual grasses. This change over many years has resulted in more erosion and slides, termed mass erosion.
For parts of the county that are flat where houses are built on what was once agricultural land, it’s possible we’ll see some trees dying in the coming months. Since much of our land has clay soil, when it was tilled in times past the tractors moving over it compacted the clay. This creates what’s called a hardpan underneath. When topsoil is put on top of hardpan a bowl is created, which holds water. Most tree roots are in the top 12 inches of soil. Trees need air in the soil and can’t last long in a bowl of water, so the longer fields and yards stay wet the more likely some trees will drown and even topple. If you observe a tree that’s declining consider getting a certified arborist out to figure out what’s happening.
Master Gardeners, in partnership with Marin Municipal Water District and other water districts in Marin, come to your garden and make recommendations on how to improve your water efficiency, as well as your soil and plant health. These water walks will resume after the ground has a little time to dry out. You can request a walk by calling 415-473-4204.
Interested in learning more? Peggy Mathers, master gardener and garden walk coordinator, will explain how our assumptions about water have changed and will continue to evolve at a free talk, “Water: Yesterday, Today and Tomorrow,” from noon to 1 p.m. March 23 at the Civic Center Library in San Rafael.