Simpson, Larry D.

English

Colorado Law

University of Colorado Law School Colorado Law Scholarly Commons Water Organizations in a Changing West (Summer Conference, June 14-16) 1993 6-14-1993 Innovative Approaches to Irrigation Conservation Larry D. Simpson Follow this and additional works at: https://scholar.law.colorado.edu/water-organizations-in-changing-west  Part of the Hydrology Commons, Natural Resources and Conservation Commons, Natural Resources Law Commons, Natural Resources Management and Policy Commons, Recreation, Parks and Tourism Administration Commons, State and Local Government Law Commons, Water Law Commons, and the Water Resource Management Commons Citation Information Simpson, Larry D., "Innovative Approaches to Irrigation Conservation" (1993). Water Organizations in a Changing West (Summer Conference, June 14-16). https://scholar.law.colorado.edu/water-organizations-in-changing-west/11 Reproduced with permission of the Getches-Wilkinson Center for Natural Resources, Energy, and the Environment (formerly the Natural Resources Law Center) at the University of Colorado Law School.     Larry D. Simpson, Innovative Approaches to Irrigation Conservation, in WATER ORGANIZATIONS IN A CHANGING WEST (Natural Res. Law Ctr., Univ. of Colo. Sch. of Law 1993).  Reproduced with permission of the Getches-Wilkinson Center for Natural Resources, Energy, and the Environment (formerly the Natural Resources Law Center) at the University of Colorado Law School.  INNOVATIVE APPROACHES TO IRRIGATION CONSERVATIONLarry SimpsonManagerNorthern Colorado Water Conservancy DistrictLoveland, ColoradoWATER ORGANIZATIONS IN A CHANGING WESTNatural Resources Law CenterUniversity of ColoradoSchool of LawBoulder, ColoradoJune 14-16, 1993CAflOUTLINEINNOVATIVE APPROACHES TO IRRIGATION CONSERVATIONBy Larry D. SimpsonGeneral ManagerNorthern Colorado Water Conservancy DistrictA. Does the irrigator really waste water? Irrigation in Colorado reuses its supplies severaltimes. The only way to impact irrigation with real conservation is to modify the consumptiveuse of the water through improved irrigation timing, decreased evaporation by improvedapplication practices and decreased transpiration from non-productive plants. Unless themodified methodologies affect the amount of water that is actually consumed, there is noactual conservation. As long as the surface or underground return flows are put to usedownstream, decrease in water use without decrease in consumption does not conserve anywater.Many highly advocated municipal conservation practices such as low-flush toilets, lowvolume shower heads, and drip irrigation of landscaping in fact are energy conservation asopposed to water conservation in that they decrease the amount of treatment capacity neededby the delivering utility. This saves both energy, treatment materials and money. It does not,however, save much water Water that passes through the waste treatment plant is in fact thewater source for agricultural use or groundwater recharge downstream. Where the waste flowsare lost to the ocean or are lost to irrecoverable saline sinks such as the Salton Sea. the abovepractices truly represent water conservation. Fortunately, such losses are rare in Colorado.B. Improved scheduling can apply the water at critical times in the plant's development.Careful measurement of soil moisture, temperature, relative humidity, and plant developmentstage can result in fewer, more effective applications of water with resultant high productivityand decreased evaporation.The use of tensiometers or neutron probes to measure the soil moisture in the root zone ofcrops and the timing of irrigations to meet soil moisture deficits reduces the loss fromevaporation from the surface of the irrigation furrows or the spray from sprinklers as well asthe loss from evapotranspiration from adjacent weed coverage. It also schedules the maximumsoil moisture availability for evapotranspiration from the crops during the time that themaximum crop needs occur such as the timing of kernel formation and flout in the instanceof corn.In some instances of very high value annual crops and for perennial crops, the use of dripirrigation can apply the water directly to the root zone and thereby decrease the evaporationfrom the surface of the soil. This practice does affect the return flow pattern of formerlysurplus flows from the field and may necessitate mitigation of damages to downstream usersthrough the release of some of the non-used water to the users downstream. Unless actualconsumption is reduced, no water is truly saved. Its pattern of flow is merely rearranged. In asystem where adequate storage and regulation structures exist or can be constructed,rearrangement of the management of the water supplies and the flow patterns can result inbeneficial results to all users including fisheries and recreation without injury to any users orlegitimate water rights.C. Innovative application methods can result in less deep percolation with resultant savingsin the leaching of valuable fertilizers and decreased pollution of the groundwater supplies.These application methods must take into account the effect on the return flow patterns forthe downstream water users and, as mentioned above, any water savings should only reflectreal decreases in the consumption of water.The use of nitrogen balancing takes into account the available nitrogen in the appliedwater, the residual nitrogen in the soil before tillage, and the amount of additional nitrogenand other fertilizers that need to be applied to meet the needs of the crop to be raised. Thisprocess Is now being utilized in the District's advisory irrigation management schedulingprogram. When combined with irrigation practices that limit the amount of deep percolationbeyond the depth of the root zone, the amount of nitrogen and other chemicals that reach thegroundwater without being absorbed by the crops is minimized. This "best managementpractice" is one of several which can reduce the nonpoint source pollution of the groundwaterby agriculture.A new methodology Is being experimented with for high value crops. This involves thedetailed survey and sampling of the fields on a square meter basis. This information on soiltype and nutrient level is stored through the use of computers and through the use of preciselocation equipment such as LORAN or precise radar. The application of precise amounts ofvarious fertilizers is then accomplished by the use of highly sophisticated equipment guided bythe computer data and the precise and continuous location of the applicator in the field. Thispractice is also being considered for the application of water through the use of variablevolume nozzles on center pivot sprinklers and through the use of locator antenna on thepivots. Obviously, such a system is very expensive. However, the increased yields andreduced fertilizer and chemical application can make the process cost effective in the instanceof high value crops such as vegetables. This experimental method is called "prescriptionfanning." It is presently in use in parts of California and Minnesota.D. Regulation versus incentives and education. The program instituted by the NorthernColorado Water Conservancy District is based upon a voluntary program of education whichdemonstrates to the farmers that he can achieve valuable production gains while, at the sametime, decreasing the loss of expensive fertilizers and lower costs of production. This type ofprogram has a much greater chance of success than one of regulation. The over-all cost ofadministration and enforcement of a regulatory program on the limited resources of thetaxpayer makes such an approach an extremely poor alternative to a voluntary program. Thecost to society to assist In the education and adoption of innovative methods is considerablylower than the cost of another layer of bureaucrats involved in irritating and ineffectiveregulation.

Innovative Approaches to Irrigation Conservation

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Innovative Approaches to Irrigation Conservation

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