How can we harness the bounty of the wet season all year long?
In the middle of California’s rainy season, it’s easy to think that water is abundant. Just a month ago, storms were passing through regularly, creeks were rushing, grassy hills were vibrant green, and water was everywhere. But recent reporting shows California isn’t out of the woods, for reservoir levels or groundwater recharge, and without several more soaking storms over the rest of the rainy season, it’s unlikely we will emerge from drought this year.
January brought lower than average rainfall and there’s no way to be sure of what’s in store in the coming months. After watching creek beds dry out and reservoir levels dip to dangerously low levels last year, imagining another season short on water can bring anxiety. It’s worth considering what we can do now, asking the question – How can we harness the bounty of the wet season all year long?
These tanks from SEC Senior Scientist Steven Lee’s property are an example of a larger scale implementation of a rain water catchment system.
There are many ways, large and small, to help rainwater find its way into the ground to recharge aquifers, or to store it above ground for future needs. Capturing rainwater is a practice that humans have employed for centuries. These techniques are important to learn more about in a region like ours, with its Mediterranean climate and “feast to famine” water season.
With the growing concern that climate change will bring a longer dry season here, implementing a rainwater catchment system into your home and garden offers one tangible solution to dry season shortages, while also supporting the local environment. Sonoma Ecology Center’s Senior Scientist Steven Lee has built a 70,000 gallon rainwater catchment and storage system that supports his livestock, garden, orchard, and landscaping, allowing him to know that his plants and animals are cared for, despite the potential for longer dry summers ahead. When restrictions go in place for watering plants during times of peak drought, or when wells start to go anemic, those with stored rainwater can pull on their own reserves.
Current water levels at Lake Sonoma have Sonoma County water storage at approximately where it was this time last year, setting us up for similar conditions as experienced last year, particularly if no more winter storms arrive.
Using rain harvesting tanks is an excellent partial solution to navigating our dry season. A typical rainwater capture system can support a garden for weeks to months, depending on size and catchment area. With five to seven months of little to no rain, though, most systems won’t fully solve dry season water needs. They are part of an array of solutions that build resilience. Also, putting water tanks on your property isn’t always possible, but there are other options for storing and managing rainwater. An option to expand the availability of scarce water is to reuse it onsite as graywater, though this solution also requires care and planning.
If you have an interest in thoughtfully managing rainwater, you can see several methods in action at Sonoma Garden Park, where Sonoma Ecology Center has implemented variety of techniques to “slow it, spread it, sink it” – a term coined by permaculture designers referencing the importance of catching rainwater, holding it on-site, and getting it into the ground. When rainwater is prevented from running off, there is a decrease in erosion and more water replenishing aquifers – both important positive ecological results.
Take a walk around Sonoma Garden Park’s beautiful gardens and explore our Low-Impact Design (LID) tour to learn about LID landscaping – a method of design that centers sinking rainwater back into the earth to recharge aquifers or storing it in other ways for later use. At Sonoma Garden Park you can view a variety of applications that support our local environment and our human day-to-day water needs. From gray water systems and roof water catchments, to swales and drought-tolerant native plantings, there are options for all styles and budgets to get started harnessing the bounty of California’s rainy season.
Get started with some rain harvesting examples from Sonoma Garden Park:
Rain Gardens: A garden of native plants, shrubs, or perennials that is planted in a shallow basin made to be ideal for capturing and filtering stormwater from rooftops and parking areas. By holding water in place for a short period of time (a rain garden should be dry when it is not raining) rain is able to sink into the ground rather than running off. Compost, water or sand should be added to the depression to ensure that water is more easily able to sink into the ground. The water garden pictured here at Sonoma Garden Park receives overflow from one of our rainwater catchment tanks. 
Roof Water Catchment: A modified downspout attached to a roof gutter system turns any roof into a large surface area for catching storm water. The two storage tanks at Sonoma Garden Park are able to hold 750 and 1,500 gallons of water each for use during the summer. Smaller and larger tanks are available to fit various needs. Roofs with an adequate slope are able to collect water during the rainy season that can be utilized for supporting agriculture, gardens, and livestock and are a great alternative to pumping from creeks or rivers. You can learn more about rain water catchment systems here. 
Drought-Tolerant Native Planting: Most plants that are native to this region require less water once established. Other good options for drought-tolerant planting include non-invasive Mediterranean species. You can visit a variety of styles, species, and combinations of drought-tolerant native planting at the Sonoma Garden Park. Sonoma Ecology Center partner, The Resilient Landscapes Coalition has a variety of resources and support for options in drought-tolerant native planting that are fire-wise, water-wise and promote the biodiversity of your home garden. 
Permeable parking lots: A gravel parking area with infiltration features and hollow pavers to hold the gravel in place is strong but permeable, allowing storm water to soak in and preventing polluted runoff. Implementing permeable parking lots allow for a larger area that is normally impermeable and that contributes to significant rain water runoff to instead recapture water and sink it back into the ground to help recharge aquifers and keep water onsite to benefit the plants that grow there. Want to learn more? Take the LID Tour in person at Sonoma Garden Park For those wanting to take the leap into onsite roof rainwater catchment systems the Sonoma Ecology Center Restoration and Research Teams are available for consultations and support in implementation of these systems. You can talk to a SEC staff member about your own projects and goals by writing to [email protected] Learn more here about rain water catchment systems
