2018-10-16_PERMIT FILE - M2018039 (2)

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Table 1.Estimated seasonal water requirement(consumptive use) in eastern Colorado(inches/season). Cheyenne Colo. Rocky Burlington Byers Wells Springs Holly Greeley Lamar Longmont Ford Springfield Sterling Trinidad Wray Alfalfa 35.64 32.13 36.14 30.04 39.34 31.58 39.06 30.91 37.75 37.44 35.24 33.29 35.24 Grass hay/pasture 31.06 27.45 31.74 26.04 34.66 26.63 34.16 26.17 32.92 32.61 28.01 28.10 30.92 Dry beans 19.22 18.42 15.83 18.75 18.75 Corn,grain 26.00 25.81 20.49 29.40 26.81 21.66 27.73 26.67 21.31 25.42 Corn,silage 22.82 22.11 18.22 26.12 21.74 19.74 24.28 20.29 19.15 Corn,sweet 22.75 20.37 Melons 15.85 15.80 15.13 Potatoes 28.14 Small vegetables 18.71 17.70 18.85 22.23 Sorghum,grain 21.51 20.46 15.99 25.20 19.48 22.64 22.65 16.09 Soybeans 10.41 Spring grains 12.49 11.82 11.36 14.15 10.44 14.29 15.17 Sugar beets 29.98 30.43 34.83 29.31 34.27 25.48 32.70 32.28 29.99 29.99 Wheat,winter 18.99 16.42 18.55 14.06 19.65 16.38 19.30 18.46 18.64 12.53 16.14 Av.Precipitation 16.35 18.57 16.26 15.73 15.33 12.20 5.33 12.74 12.53 15.36 14.92 12.80 18.51 Av.Effective Precipitation 11.28 10.39 11.68 10.59 10.72 7.32 11.00 6.99 8.89 10.93 6.68 8.28 12.56 Yield vs Evapotranspiration In Colorado's semi-arid climate,ir- Yield vs. ET and Irrigation rigation is important to increasing ET and ,gyp _.._.. .. _._ ___ ____, Crop yields increase linearly with the l0000 gram yields,supplementing rainfall in water that is used by the crop(Figure 1). troop � � periods when ET is greater than precipita- Crops such as corn,respond with more er000 tion.However,not all of the water applied yield for every inch of water that the crop b irrigation is used for ET.Inefficiencies in � Hoop y g consumes as compared to winter wheat or - ' 2000 applications by the system result in losses. sunflower.High water use crops,such as 0 As yield is maximized,more losses occur corn,require more ET for plant develop- 0 s to is 20 25 30 since the soil is closer to field capacity and ment or maintenance before yields are Evpotr"neorsdon(inch") more prone to losses,such as deep percola- produced.Corn requires approximately ----winter wheat- - sunflower-Corr, tion,which cause the deviation from the 10 inches of ET as compared to 4.5 and Figure 1:Yield vs.ET relationship for straight line(Figure 2).By applying less 7.5 inches of ET for wheat and sunflower. several irrigated crops. than needed for maximum yield,water can 9 P These crops also require less ET for maxi- be saved.As seen in Figure 2,a reduction in mum production compared to corn. r �~ a terwaterapplied ith m point orno yield point Bc can n. Irrigation is important to increasing ietd vs E.t' / Y. AET and grain yields.Irrigation is used to r supplement rainfall in periods when ET is .� Limited Irrigation g pp greater than precipitation.However,not t iekl,s Irrigation all of the water applied by irrigation can be When water supplies are restricted in used for ET.Inefficiencies in applications by some way,so that full evapotranspiration demands cannot be met,limited irrigation the system result in losses.As yield is maxi- results.Reasons that producers maybe mized,more losses occur since the soil is nearer to field capacity and more prone to limited on the amount of available water losses such as deep percolation(Figure 2). «'ater{F;'1'or Irritation) include: 1.)limited capacity of the irriga- Water can be saved b applying less water tion well-in regions with limited saturated y a y g Figure 2:Generalized Yield vs.ET and than needed for maximum yield.As seen in Yield vs.Irrigation production functions. depth of the aquifer,well yields can be mar- Figure 2,a reduction in water applied from ginal and not sufficient to meet the needs of point A to point B can save water with little In Colorado's semi-arid climate,ir- the crop;2.)reduced surface water storage in regions that rely upon surface water, or no yield reduction. - rigation is important to increasing ET and g y p grain yields,supplementing rainfall in droughts and seasonal fluctuation affect the f bl il i llocatons available or users. periods when ET is greater than precipita- water a When producers are faced with tion.However,not all of the water applied When producers cannot apply water reduced surface water supplies,they by irrigation is used for ET.Inefficiencies in to meet the crop ET,they must realize that have three management options applications by the system result in losses. with typical management practices,yields As yield is maximized,more losses occur and returns will be reduced as compared to 1. reduce irrigated acreage, since the soil is closer to field capacity and a fully irrigated crop.To properly manage more prone to losses,such as deep percola- the water for the greatest return,producers 2. reduce irrigation amounts to the tion,which cause the deviation from the must understand how crops respond to wa- entire field,or straight line(Figure 2).By applying less ter,how crop rotations can enhance water 3. include different crops that require than needed for maximum yield,water can availability,and how changes in agronomic less irrigation. be saved.As seen in Figure 2,a reduction in practices influence water needs. water applied from point A to point B can save water with little or no yield reduction.