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MMWD Blog: Think Blue Marin

Welcome to our blog! Written by staff at MMWD, “Think Blue Marin” explores all things water in south and central Marin—water supplies, conservation, new projects, watershed management, and more.

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Jan 13

In the News

Posted on January 13, 2017 at 2:58 PM by Ann Vallee

by Charlene Burgi

Misty
 Misty checks out a nature-made rain garden
Lately not a day goes by without weather warnings notifying me of blasting blizzard conditions, flash flood warnings, ice on the roads and recommendations to stay indoors. The warnings, however, are not exclusive to us here in Lassen County. While watching the Bay Area news this week, I saw highway and road closures throughout Marin, evacuation and flooding in San Anselmo, and Corte Madera Creek rising to flood stage. I even saw videos of people surfing and boogie-boarding down rain-swollen Mill Creek.

These news warnings are a reminder that we need to be extremely careful when landscaping to keep our homes safe. Standing water or flooding can be an indicator of drainage design flaws. Sometimes these flaws do not reveal themselves until we experience what is known as the 100-year-storm scenario. A mild or modest rainfall may have no ill-effects on our property, but then an unusually big storm exposes the problem. An example of this occurs when water can no longer percolate down into the soil before running off. If the runoff exceeds the drain capacity on the property, or if the grading was crowned or sloped toward the house, excess water can end up under the house—or in the house if the home is on a slab. A good drainage design calculates for the worst historical rain conditions to draw water away from the house.

There are steps we can take to correct design flaws and help stormwater "slow down, spread out and soak in." If you live on a hillside, you can create multiple bioswales, such as bark-filled troughs, along the width of the hillside. Stormwater collects and slowly percolates into in each swale before continuing to the one below, thus eliminating the rush of unrestrained water flowing off the hillside. 

dry creek bed
Functional dry creekbed
Trenches designed as functional dry creekbeds can divert water away from the house and into a rain garden—a simple, shallow, pond-like area where the water can safely collect. Landscape your rain garden with plants able to withstand a lot of water in winter and minimal irrigation in the summer. Many iris, Monarda, asters and even the monarch-butterfly-attracting Asclepias are great for sunny rain gardens. Or choose ferns, blue-eyed grasses and Mimulus for shade. For more plant ideas, visit: raingardenalliance.org.

If you live in a flood zone, be prepared to evacuate if instructed to do so. In addition, plan ahead by stocking cupboards with extra food and water in case you are told to "shelter in place," lose power or are unable to get to a store. Keep extra warm clothing and shoes in your autos and do not attempt to drive through flood waters.

Be safe and have a great weekend.

Comments

Anonymous User
January 14, 2017 at 11:55 AM
Charlene, Unfortunately, the reference to the Rain Garden Alliance site for plant ideas in the January 13 Weekly Watering Schedule was not particularly useful since the plants listed are for Pennsylvania. However, much closer to home the California Native Plant Society has created a new interactive website, CALSCAPE, that gives you the information you need to select native plants appropriate for your particular garden location. http://calscape.cnps.org/search.php . CALSCAPE will even create lists of native plants that are appropriate for specific microclimates in your yard: full sun, deep shade, fast draining, boggy, etc. And it even tells you the specific nurseries that sell the plants you need and gives you horticultural information on each plant you choose. The plant selection tools on this site are so powerful that you can get about as fine-grained as you desire in selecting plants. The criteria you can use in selecting appropriate plants include: Plant Type, Sun, Drainage, Water Requirement, Ease of Care, Common Uses (e.g., butterfly gardens, bank stabilization), Availability in Nurseries, Fragrance, Flower Color, Flowering Season, Height, and Genus. I have tested CALSCAPE out on my own native plant garden which uses mostly plants native to Marin County. When I created this garden about a decade ago, I spent many hours selecting locally native plants appropriate for the multiple microclimates in my yard. CALSCAPE replicated these selection criteria in a few minutes, giving me lists of plants meeting various criteria that Iargely mirrored the list of plants now in my garden. I was impressed. CALSCAPE is a native plant selection tool that can quickly identify the native plants appropriate for a particular garden location in California. It needs to be better known. Thanks. David Long Co-Vice President Marin Chapter, CNPS
Charlene Burgi
January 18, 2017 at 10:19 AM
Thank you for this information, David! This is indeed a valuable tool and I will investigate it further with the intent of writing a blog about it.

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