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A plea for sane lawn watering
Washington Conservation District
Remember back in grade school when the kid in front of you at the drinking fountain would slurp away for what seemed like an eternity until finally someone screamed, “Save some for the whales!?” Well, I’m betting that kid grew up, bought a house with a big lawn, and programmed his automatic sprinklers to go off every other day, regardless of whether it is raining or not. He’s probably sitting in his living room right now, watching the rain slide down the window panes as the sprinklers rhythmically pulse outside, and thinking, “Ain’t no one going to tell me to turn off the water now.” I mean, there has to be a logical explanation for people who water their lawns in the rain, right?
Last month, the city of Woodbury reported that they pumped 9.3 million gallons of water to residents and businesses on Saturday, June 14, a day in which we received two inches of rain. That is more than twice as much water as Woodbury pumps on a typical winter day, indicating that irrigation, not indoor water use, was to blame.
The problem doesn’t just happen in Woodbury, however. Drive around any city in the area, and you can see sprinklers going in the rain or folks watering already water-logged lawns. I doubt people are doing this on purpose, but as in-ground automatic sprinklers become more common, the problem will continue to grow.
Since most people have their sprinklers set to go off early in the morning, going outside to manually turn them off on rainy days isn’t always a popular option. Rain sensors can be installed on sprinkler systems so that they automatically turn off whenever it is raining. There are a variety of models available for as little as $25-$35. In fact, the city of Woodbury requires all new watering systems (except for single-family residential properties) to be equipped with rain sensors.
Soil moisture sensors are more expensive ($100-$150) but the best technology for ensuring that lawns only get watered when they need it. Program the irrigation controller with your lawn’s moisture requirements and a sensor will allow the irrigation system to turn on when the soil is dry, but not when it is already wet.
In addition to installing rain sensors or soil moisture sensors, residents and businesses can reduce the amount of water they use by following lawn watering guidelines established by the University of Minnesota Extension and other turf maintenance experts. In general, lawns in Minnesota need no more than one inch of water per week. In rainy times, such as these, this usually means you won’t need to irrigate at all. When there is no rain, dividing the watering up will help to ensure that the water can all soak into the ground instead of running off. Shoot for ½ inch of water, two times per week, during the spring and fall and ¼ inch, every other day, during the hottest summer months. A typical pop-up spray head takes 20 minutes to apply ½ inch of water, while a typical rotor-type sprayer will take 40 minutes. On compacted soils, aerate once per year around Labor Day (20-40 holes per square foot) to help break up compaction over time so that the grass’s roots can grow deeper and water is better able to soak into the soil.
Being smart about lawn watering helps to protect our groundwater drinking supplies for future years and means a cheaper water bill and healthier grass as well. So, save some water for the whales, hey?
Angie Hong is an educator for East Metro Water - www.mnwcd.org/emwrep - which includes Brown’s Creek, Carnelian Marine - St. Croix, Comfort Lake – Forest Lake, Middle St. Croix, Ramsey Washington-Metro, Rice Creek, South Washington and Valley Branch Watersheds, Cottage Grove, Dellwood, Forest Lake, Lake Elmo, Stillwater, West Lakeland, Willernie and Woodbury, Washington County and the Washington Conservation District. Contact her at 651-330-8220 x.35 or firstname.lastname@example.org.