THE COASTAL GARDENER:

One of the significant natural processes on earth is the soil’s ability to act as a cleansing filter for water. Water, either from rainfall or irrigation, eventually finds its way back into the ocean or into underground water-storing aquifers.

In urban spaces such as most of Orange County, however, we’ve covered much of our landscape with solid, impermeable surfaces that do not allow water to filter back into the earth. Additionally, most of us live on properties that have been designed specifically to remove water from our properties, and to do it as quickly as possible.

Our roofs have gutters that channel water directly to the street. Our concrete and stone patios and walkways send more water off our properties. Two- and three-car driveways are paved solid and angled noticeably; perfect for delivering water directly to a sidewalk. Of course, sidewalks (another impermeable surface) move the water quickly to the street. There, the water from our property is quickly added to the water collected by an ocean of solid asphalt. Pushed to the gutter, it flows unchecked into the Pacific Ocean, lost forever. But not before it picks up and takes with it whatever is in its path; invisible fertilizers, pesticides, snail baits, motor oil, pet feces, lead, arsenic, sediments and more.

In a natural state, before we built homes and gardens, sidewalks and streets, a great deal of this water would have percolated into the soil. But our landscapes and public spaces have been masterfully designed to bypass the natural water cleaning process of our soil. Instead, we’ve created a perfect model for not storing water, not cleaning it. We’ve masterminded a brilliantly efficient method to deliver pollutants as quickly and as efficiently as possible into our oceans. As concerned gardeners, what can we do? First, we should question the fundamental belief that moving water off of a property quickly and efficiently is a valid goal. The idea that excess water should not necessarily leave a landscape will take a little getting used to. For many, this will seem at odds with our fundamental assumptions. The concept will take a little getting used to.

Next, increasing the permeability of a landscape might be a good place to start. There are two crucial benefits to permeable surfaces. Firstly, these surfaces slow down the water that moves over them. Slowly moving water allows many of the solid pollutants and sediments to drop out of the water. Secondly, when solid surfaces are replaced by permeable surfaces water infiltration can occur over a much greater area.

Permeability revolves around replacing non-porous surfaces with those that allow water, at least to some degree, to infiltrate through them and into the soil below. Some of the techniques used to increase permeability are redesigning driveways, breaking up solid concrete surfaces and separating the pieces, rethinking roof gutter downspouts, changing grades and soil contours and being creative with patios.

Another way a homeowner can reduce runoff is by retaining water in a landscape. Retention gives the water an opportunity to infiltrate into the soil, being cleaned and purified as it goes; eventually arriving in an aquifer below. In Orange County, almost every city depends on ground water for some part of its total water supply. Many people are still unaware of the size of Orange County’s huge underground reservoir; 30% larger than Lake Mead.

This week, as the rain is falling and the water is flowing, take a moment to consider how that water, streaming into the gutter, could be better used. Next week I will explain some other easy ways to manage and reuse the water in your home landscape.

RON VANDERHOFF is the Nursery Manager at Roger’s Gardens, Corona del Mar.