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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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Aug 17

The Sponge

Posted on August 17, 2018 at 7:35 AM by Ann Vallee

by Charlene Burgi

Recently, for the third year I found my way to our Canadian friends’ choice location to do some amazing hikes and throw a fly into pristine lakes for the chance of catching the famed Kamloops trout. Before leaving on vacation, I promised to share with you my plant experiences while north of Kamloops, BC. 

wild blueberries
 Wild blueberries

 product of living soil
 Product of living soil
Mornings found a few arduous fishermen on the narrow trails leading through the heavily forested lands to pristine lakes. The vegetation surrounding us consisted of tall timber and lush green growth. Various colors and shapes of mushrooms appeared all around us. Tucked among the trees were bushes covered with huckleberries and blueberries ripe for the picking, which seemed to lighten the load of our gear as we hiked on. 

But it was the sponge-like soil underfoot that particularly captured my attention. It seemed as if it was alive. Years of built-up duff from fallen, decomposed plant material fed this soil teeming with microorganisms. I couldn’t help but think of it as the quintessence of what we strive to achieve in our gardens. Only layers of well-rotted compost could duplicate the perfection of this soil.

I chatted about the wealth of the soil with the owner of the lodge where my oldest grandson Steve and I stayed. She made a comment that surprised me. She said there were only about three inches of this fertile, sponge-like soil covering the hardpan clay underneath. Her statement left me speechless and wondering what this rich environment would be like without the interface layer of the two elements. Of course, the thought of double-digging a landmass of that scope is absurd, but in a home garden? The idea struck home that I could do a lot more with the rotting manure from my chickens, horses and donkeys to enrich my own garden. That living sponge is doable for all of us!

Not all of us have equine or chickens in our backyards, but we can compost. We can add organic layers of thick mulch over cardboard or any material that will decompose in time. The duff build-up from the forest did not occur overnight, and it will take time in our backyards, too. But our commitment to feeding our soil will pay off in a multitude of ways if we stay the course. Our plants will thrive, and our vegetables, fruit trees and shrubs will out-produce. Our gardens will need less irrigation thanks to the moisture-retaining properties of those layers of organic material, and weed seeds will have difficulty germinating—or at the very least plucking them out will be much easier if they do manage to set down a root.

Are you up for the challenge? Visit a local dairy or equine center and ask what they do with their manure. They might be willing to share several truckloads on an ongoing basis. (Just be certain it is well-rotted and weathered to leach out any existing salts.) Then join me in creating a living sponge in our gardens.

Aug 09

A Weather Station from Space

Posted on August 9, 2018 at 2:22 PM by Ann Vallee

by Christina Mountanos

Last month a few of us in the Water Conservation Department journeyed out to the far end of the driving range at Peacock Gap Golf Course for a quick refresher on how to care for our California Irrigation Management Information System (CIMIS) weather station. We met with a representative from the Department of Water Resources (DWR), who recently equipped the core of the weather station with a new data logger, and upgraded some of its other measuring components, too.

Our field trip made me realize that we often reference evapotranspiration (ET) in our Weekly Watering Schedule blog, but seldom mention how it’s actually measured and, specifically, how MMWD measures it. See the picture below and you’ll see the stately, robotic-looking weather station that does just that for us. The technology behind it is very cool, and it’s always a treat to physically visit the site; it’s fun for me to explore this particular technical aspect of our job.

As you may know, evapotranspiration (the combined amount of water that evaporates and transpires from soil and plants) is dependent on five main factors: solar radiation, temperature, humidity, wind and precipitation. Accordingly, our CIMIS weather station has devices that measure each of these factors. For example, the contraption that looks similar to a beehive is what measures temperature and humidity. (You may see a mini version of this if you have a smart controller with its own weather station.) The arm with a flat metal plate at its end has a device on it that measures solar radiation, and it’s called a pyranometer. The arm just behind and below that with the cupped, spinning component—an anemometer—measures wind speed. Finally, the cylinder/funnel-shaped piece of equipment that sits high up on the station measures rainfall. All of these components need regular cleaning and care to ensure they are measuring accurately and transmitting the correct data, hence our recent refreshment training. (You might also notice the solar panel on the base, which is what powers the station.)

The CIMIS station collects data daily and the data is uploaded online. Each week before sending out the Weekly Watering Schedule, we tally daily ET amounts from the CIMIS website, total them together (for a weekly total) and then plug them into special equations that determine suggested minutes for watering. In a nutshell, that’s the process.

And, just to leave you with a couple of last notes that you may find interesting: To measure accurately, CIMIS stations need to be placed in an open area (where buildings or trees will not affect wind speed), on top of maintained, cool-season grass. This is why stations are often located on golf courses. MMWD’s station is actually part of a much larger collection of about 145 weather stations in California, all managed by DWR since 1985, and created in an effort to encourage smarter irrigation practices. 

If you’d like to learn more about CIMIS and other details about the California network of weather stations, you can read more on the official CIMIS webpage

I hope you find this technology as interesting as we do!

CIMIS station
Aug 03


Posted on August 3, 2018 at 10:37 AM by Ann Vallee

by Charlene Burgi

The proverbial saying that “the proof is in the pudding” comes to mind as we monitor our irrigation systems during the heat of summer. During this time of year, dry spots may appear in our lawns or other groundcovers, or we may see tender plants wither or wilt due to lack of water. 

Without uniform distribution, some parts of the garden cannot get adequate water from our irrigation systems. And in trying to reach those dry areas, we end up flooding other areas and wasting water to compensate for a poorly designed system.

 Using ag risers for unblocked head to head coverage
Using ag risers for unblocked
head-to-head coverage
What does a good irrigation design look like? Appearance is easy to describe. Irrigation heads on each station or valve need to be installed so the water from one sprinkler head will reach out touching surrounding sprinkler heads. However, the calculations of friction loss through pipes, and numbers such as gallons per minute, water pressure and elevation changes are but a few of the hidden secrets that equate to good irrigation design.

For example, the aforementioned head-to-head coverage may look adequate from above the ground, but if the water pressure is lacking to push the water the distance needed to reach the other heads, the design will fail. Or, there may be adequate pressure but too many heads on one valve. As a result, the valves need more gallons per minute than the pipes can deliver, causing the water to fall short of the other targeted sprinkler heads.

Another fatal flaw in irrigation design is mixing different types of irrigation on the same valve. One common mistake I see is drip spray heads on the same valve as drip emitters. Drip sprays apply water measured in gallons per minute (GPM) while drip emitters discharge water measured in gallons per hour (GPH). By mixing the two methods of irrigation on the same valve, some plants will be flooded with GPM while other plants will be starved for water dribbling out in GPH.

The same holds true for overhead spray systems. The goal is to have the overhead irrigation sprays provide an equal gallons per minute to the area they are covering. We call this having matched precipitation rates. This can only be achieved by using the same model nozzles on the same valve. For example, mixing an impact head with a rotor on the same valve would be a disaster for the plants: Given the same pressure, a rotor will emit roughly three gallons of water per minute and an impact head will throw out over five gallons of water per minute. You can see how under this scenario some plants will lack water while others get too much. This mix-and-match problem can even occur by using the same type of spray heads but from different manufacturers.

In essence, poor irrigation system designs equate to water waste, not to mention the stress placed on your plants. Take a walk in the garden with your sprinklers on to see how well your system is working. While you are at it, check for broken lines, missing emitters and nozzles that are spraying in unintended areas. Correct the problems and you will find your efforts reflected in lower water bills and happier plants!

I will be off line next week casting a fly into the beautiful lakes above Kamloops. I promise to share more about the beauty of native plants in British Columbia upon my return. Until then, ciao!