The California drought continues to make headlines as the regulators sort through what will be the final water-use restrictions for the state as a whole and for each water district in particular. What we have seen so far, as usual with regulation, it’s not based on science, but based on emotion. No big surprise.
Emotion is short term. Unfortunately, what is going on in California are short-term emotions dictating long-term water-use regulation. It’s a knee-jerk reaction not based on science. That cannot be good and it will not be as the weather will change.
Last year, in the middle of June, most of Texas was in extreme or exceptional drought. This year, in the middle of June, there is only one small area of the state showing abnormally dry weather. This year, in the middle of June, almost the whole state of California is shown to be in exceptional drought. Last year, at the same time, most of the state was in extreme drought and less so exceptional. The California drought is in its fourth year with no end in sight, but weather patterns are cyclic and at some point it will be over. Australia went through a 10-year drought that disappeared in one year, much like what is happening in Texas.
The California drought plan is geared toward turf removal and new landscapes without turf. One area not receiving much attention is the regulation on precipitation rates. The laymen’s feeling (the regulator) is that high precipitation rate sprinklers waste water and they need to be eliminated. Basically, they are trying to eliminate spray heads or sprinklers with precipitation rates over 0.75 or 1.00 inches per hour, though I’m not sure which it will be yet. There might be one for slopes and another for everything else.
The spray sprinkler isn’t wasting the water. The person keeping it on too long or the irrigation schedule is wasting water. Spray sprinklers are not the only irrigation with precipitation rates over 0.75/1.00 inches per hour. Most driplines have a precipitation rate above 0.75 inches per hour. So what does this have to do with golf course irrigation?
Let’s look at your greens. If you have four sprinklers watering a green on 70-foot spacing and the sprinklers are all full circle, operating at 80 psi they use 25.8 gpm each. This results in a precipitation rate of approximately 0.51 inches/hour. At 65 psi even higher, 0.61 inches per hour. No big deal, but many golf courses have parts in and parts out on their greens of full circles for the green and parts out. Some courses have a similar arrangement on the tees. If the sprinklers are set for part-circle operation, either in or out, the precipitation rate approximately doubles, if the arc is set 180 degrees, to 1.02-1.22 inches per hour. If the arcs are less than 180 degrees, the precipitation rate will be even higher. Any part circle large rotor sprinkler is going to have a high precipitation rate.
The draft regulations have a requirement for irrigation efficiency of 0.85 inches for residential areas and 0.92 for non-residential areas.” Golf has consistently had the highest irrigation efficiencies of any irrigation sector, but that is considered to be a maximum of 0.80 to 0.85. No irrigation equipment has the ability to reach efficiencies as high as 0.92. Once you throw water into the air, as we do in golf irrigation, there are inherent losses that cannot be mitigated. You can irrigate all your turf with sub-surface drip, but maintenance and aeration will be a challenge.
What else can you expect? Well metering for sure. You may not have to report your water use on a regular basis, but you will be required to know it in case someone with authority asks and you’ll have to justify your response with data. If you don’t measure your water use, you can’t manage it, so metering your withdrawal should be done with no argument. Do yourself a favor, even if the regulations say you only have to meter, for example, your groundwater withdrawals, meter all your sources. Make sure you record how much water you are pumping. Reset your pump station flow totalizer and write it down at least once a week if not every day so you know your water use.
Brian Vinchesi, the 2009 EPA WaterSense Irrigation Partner of the Year, is president of Irrigation Consulting Inc., a golf course irrigation design and consulting firm headquartered in Pepperell, Mass., that designs irrigation systems throughout the world. He can be reached at firstname.lastname@example.org or 978/433-8972.