High water bills have prompted homeowners to investigate the efficiency of the sprinkler system for their properties. Many homeowners trying to water within regulations or recommended watering levels are observing extensive plant stress, particularly in turf. When turf areas are under-watered they typically exhibit blotchy patterns of stress. Our experience is that such variability becomes manifest as water application is reduced due to multiple factors such as; uneven distribution of water over the area, varying soil conditions, shifting patterns of shade and sun, seasonal fluctuations in evaporation, and variations in weather. Other factors that produce similar symptoms include disease, animal urine, over- or uneven application of fertilizer.
Focusing only on water-related factors, it is necessary to water any given section of plant material to the highest need in that section in order to achieve relative uniformity of appearance. Except for very large areas such as football fields, golf courses, and large floral parks where spacing of sprinkler heads is not dictated by tight or curvilinear plant borders anything approaching optimum sprinkler application efficiency is not possible. Under the best conditions, the efficiency of application of water by sprinklers (or even drip) only approaches 70%. Typical urban and residential properties will be much lower, even with the best design and equipment. Statewide standards for irrigation efficiency have been developed based on ideal spacing of sprinkler heads in the absence of obstructions, imprecise borders, etc.. As a result, adoption of water conservation regulations has an overall fundamental bias against the typical homeowner from the beginning. This bias pushes the homeowner towards watering to the minimum for the least needy portion of a section of plant material, leaving the higher need areas stressed. With water regulations based on this type of standard, most homeowners will be penalized for higher than theoretically "necessary" watering levels to avoid stressing plant material.
However, there is an even more confining element to California state-mandated water regulations and standards -- that is choice of plant material. Even if a sprinkler system was at peak efficiency, much or most of plant material in residential gardens may exhibit severe stress under mandated water regulations or recommendations because most regulations are not based on existing plant materials or homeowner choices of desirable plant material, but on what someone else has decided homeowners should choose. Some people in power positions in the state and some communities have decided that the appropriate flora for Southern California is desert, and that anybody who chooses non-desert plant materials should be penalized with fines or higher water rates if they try to water accordingly. Tiered watering rates make sense when they relate to the increased costs of obtaining more water and are essentially tied to market forces. However, some communities are imposing much higher rates and penalties which are not tied to market forces but political ideology that impose an artificial uniformity of life-style. Under these definitions, a term such as "Excessive Use Charge" does not necessarily denote that a homeowner is being penalized for reckless use of water, but rather that the homeowner is being penalized for attempting to maintain plant material that does not conform with desert ideology.
This is important to understand because with typical home landscaping you can never be good enough to satisfy the standards of the regulatory agencies unless you severely stress or kill the plants. Even then it is important to realize that most water regulations are based on an annual average and do not allow for variations throughout the seasons. For instance, regulations in the City of Los Angeles only allow for watering levels at about 1/2 the summer level for the average landscape throughout the year, including the summer. Thus at this time of year, homeowners attempting to comply strictly with City of Los Angeles restrictions are experiencing severe dieback in their gardens.
With the above limitations in mind, the objective for sprinkler maintenance for existing plant material is to try to eliminate gross imbalance where practical. This will not eliminate plant stress, but will tend to even out the stress. Another measure that may provide practical benefits is to change the sprinkler controllers to ones that either automatically adjust watering times by season, or ones that have a weather sensor that adjusts watering times for daily changes in weather. Here's the rub, however. Under regulatory guidelines, watering times in the summer are about half the normal recommended level to maintain healthy plant material, especially for turf. Improving efficiency will improve, but not remedy that sort of problem. Also, smart controllers are typically designed to meet normal water needs of plants. Smart controllers will always call for watering beyond severe regulatory levels, and therefore have little impact throughout at least half of the year.
