Pond Evaporation Calculation 11/2/11
Weather Station Data provided by Northern Colorado Water Conservancy District
See Weather Station Location Map at:
http://www.northernwater.org/WaterConservation/WeatherandETData.aspx
Notes:
Current month reflects values through "Reference Date".
Pond Evap. calculated per recent Division 1 Water Court decree language: Lower South Platte Home Page
Gross Pond = .84(Alfalfa ETr) Pond Evaporation Reports Main Menu
Net Pond = .84(Alfalfa ETr) - .7(Total Precip)
Alfalfa reference ETr computed by Standard ASCE equation from daily weather data.
Winter pond evap. is a reference for unfrozen ponds.
For Growing Degree Days:
Tmax = 86 F, Tmin = 50 F and Tbase = 50 F
Totals
Weather Station 2009 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 29.88 33.91 38.5 46.79 59.16 65.27 70.65 68.59 60.95 40.39 38.76 18.46 47.61
Ref date as of 12/31/2009 Total Precip " 0.36 0.5 0.31 3.72 3.31 6.43 3.42 3.98 2.16 2.15 0.23 0.39 26.96
Site Type: Alfalfa Total Alfalfa ETr " 4.06 3.27 5.9 5.78 7.68 7.18 8.26 7.64 5.97 3.09 3.31 1.35 63.49
Total Growing Degee Days from March 1 0 0 165 175 346 481 627 581 421 111 115 6 3028
Gross Pond Evap Total " 3.41 2.75 4.96 4.86 6.45 6.03 6.94 6.42 5.01 2.6 2.78 1.13 53.34
Net Pond Evap Total " 3.16 2.4 4.74 2.25 4.13 1.53 4.54 3.63 3.5 1.09 2.62 0.86 34.45
Crook Avg. Temp F 29.41 33.24 37.87 45.74 58.04 64.69 70.12 68.06 59.7 40.35 37.73 18.57 46.96
Ref date as of 12/31/2009 Total Precip " 0.21 0.53 0.15 2.88 2.76 5.43 1.57 2.23 2.34 1.49 0.24 0.28 20.11
Site Type: Alfalfa Total Alfalfa ETr " 3.96 3.24 5.88 5.6 7.05 6.71 8.04 7.63 5.32 3.29 3.36 1.52 61.6
Total Growing Degee Days from March 1 0 0 164 158 330 466 610 568 399 114 116 9 2934
Gross Pond Evap Inch 3.33 2.72 4.94 4.7 5.92 5.64 6.75 6.41 4.47 2.76 2.82 1.28 51.74
Net Pond Evap Inch 3.18 2.35 4.83 2.69 3.99 1.84 5.65 4.85 2.83 1.72 2.65 1.08 37.66
 
Sterling Avg. Temp F 30.07 34.34 38.7 46.18 58.57 65.63 70.81 68.82 60.43 41.24 38.11 19.74 47.72
Ref date as of 12/31/2009 Total Precip " 0.43 0.87 0.57 1.8 1.96 3.51 1.4 3 2.58 2.21 0.28 0.35 18.96
Site Type: Alfalfa Total Alfalfa ETr " 3.79 3.67 5.86 5.81 7.29 6.87 8.49 8.15 5.49 3.32 3.34 1.56 63.64
Total Growing Degee Days from March 1 0 0 174 174 344 482 625 583 394 127 127 11 3041
Gross Pond Evap Inch 3.18 3.08 4.92 4.88 6.12 5.77 7.13 6.85 4.61 2.79 2.81 1.31 53.45
Net Pond Evap Inch 2.88 2.47 4.52 3.62 4.75 3.31 6.15 4.75 2.81 1.24 2.61 1.07 40.18
 
Brush Avg. Temp F 29.91 34.65 39.09 46.5 58.72 64.89 70.44 68.75 60.76 41.73 37.48 20.37 47.77
Ref date as of 12/31/2009 Total Precip " 0.05 0.12 0.11 1.77 1.61 3.98 4.54 0.92 1.56 1.78 0.51 0.47 17.42
Site Type: Alfalfa Total Alfalfa ETr " 3.29 3.7 5.76 5.85 7.12 6.94 8.36 7.9 6.01 3.53 2.93 1.58 62.97
Total Growing Degee Days from March 1 0 0 168 184 351 484 639 588 414 130 121 14 3093
Gross Pond Evap Inch 2.76 3.11 4.84 4.91 5.98 5.83 7.02 6.64 5.05 2.97 2.46 1.33 52.9
Net Pond Evap Inch 2.73 3.02 4.76 3.68 4.85 3.04 3.84 5.99 3.96 1.72 2.1 1 40.69
 
Fort Morgan Avg. Temp F 29.79 34.83 39.46 46.6 59.31 64.94 70.29 68.85 61.3 41.88 37.52 20.66 47.95
Ref date as of 12/31/2009 Total Precip " 0.15 0.25 0.47 3.11 2.51 5.58 6.48 0.75 1.6 1.74 0.5 0.58 23.72
Site Type: Turf Total Alfalfa ETr " 3.08 3.46 5.35 5.64 7.33 6.68 7.79 7.4 5.7 3.16 2.65 1.48 59.72
Total Growing Degee Days from March 1 0 0 160 178 356 485 633 580 418 131 117 14 3072
Gross Pond Evap Inch 2.59 2.91 4.49 4.74 6.16 5.61 6.54 6.22 4.79 2.65 2.23 1.24 50.17
Net Pond Evap Inch 2.48 2.73 4.17 2.56 4.4 1.71 2.01 5.69 3.67 1.44 1.88 0.84 33.58
 
Wiggins Avg. Temp F 29.08 34.24 38.75 46.02 58.48 64.31 69.76 68.37 60.76 41.33 36.61 19.94 47.3
Ref date as of 12/31/2009 Total Precip " 0.08 0.11 0.17 2.38 1.36 4.9 2.06 1.06 1.27 1.48 0.6 0.46 15.93
Site Type: Alfalfa Total Alfalfa ETr " 3.15 3.87 6.12 6.1 7.86 7.03 8.23 7.95 6.4 3.43 2.68 1.46 64.28
Total Growing Degee Days from March 1 0 0 161 182 351 470 607 565 412 128 116 7 2999
Gross Pond Evap Inch 2.65 3.25 5.14 5.12 6.6 5.91 6.91 6.68 5.38 2.88 2.25 1.23 54
Net Pond Evap Inch 2.59 3.17 5.02 3.46 5.65 2.48 5.47 5.94 4.49 1.85 1.83 0.9 42.85
 
Fort Collins East Avg. Temp F 31.68 34.53 39.46 44.95 57.66 62.34 67.88 66.54 59.09 40.39 36.78 20.07 46.78
Ref date as of 12/31/2009 Total Precip " 0.15 0.09 0.45 3.34 1.77 4.25 1.71 0.21 0.6 1.41 0.53 0.76 15.27
Site Type: Alfalfa Total Alfalfa ETr " 3.68 3.63 5.77 5.44 7.09 6.31 7.38 7.13 5.52 3.53 2.81 1.36 59.65
Total Growing Degee Days from March 1 0 0 140 164 320 408 548 516 381 117 112 4 2710
Gross Pond Evap Inch 3.09 3.05 4.85 4.57 5.96 5.3 6.2 5.99 4.64 2.97 2.36 1.14 50.12
Net Pond Evap Inch 2.99 2.99 4.53 2.23 4.72 2.33 5 5.84 4.22 1.98 1.99 0.61 39.43
 
Eaton Avg. Temp F 29.98 34.16 38.84 45.41 57.9 62.25 66.4 64.42 58.05 39.09 34.77 18.84 45.84
Ref date as of 12/31/2009 Total Precip " 0.14 0.07 0.31 2.86 1.98 3.61 1.57 1.56 0.67 1.04 0.45 0.7 14.96
Site Type: Alfalfa Total Alfalfa ETr " 3.54 3.82 6.01 5.84 7.17 6.41 7.02 6.53 5.55 3.29 2.53 1.3 59.01
Total Growing Degee Days from March 1 0 0 143 171 331 415 520 496 371 106 98 4 2655
Gross Pond Evap Inch 2.97 3.21 5.05 4.91 6.02 5.38 5.9 5.49 4.66 2.76 2.13 1.09 49.57
Net Pond Evap Inch 2.88 3.16 4.83 2.9 4.64 2.86 4.8 4.39 4.19 2.04 1.81 0.6 39.1
 
Johnsons Corner Avg. Temp F 33.05 36.48 41.11 45.6 57.67 62.66 68.89 67.09 60.54 40.36 38.22 20.91 47.72
Ref date as of 12/31/2009 Total Precip " 0.31 0.34 0.63 3.09 1.84 2.78 3.34 0.49 1.03 1.37 0.55 0.84 16.61
Site Type: Alfalfa Total Alfalfa ETr " 3.36 3.54 5.58 5.01 6.58 6.1 7.69 7.05 5.61 3.13 2.56 1.35 57.56
Total Growing Degee Days from March 1 0 0 148 163 329 421 580 531 393 111 105 3 2784
Gross Pond Evap Inch 2.82 2.97 4.69 4.21 5.53 5.12 6.46 5.92 4.71 2.63 2.15 1.13 48.34
Net Pond Evap Inch 2.61 2.74 4.25 2.05 4.24 3.18 4.12 5.58 3.99 1.67 1.77 0.55 36.75
 
Gilcrest Avg. Temp F 30.07 34.66 39.83 45.74 58.5 63.47 68.53 67.08 60.01 40.42 36.09 19.24 46.97
Ref date as of 12/31/2009 Total Precip " 0.1 0.06 0.48 3.54 1.37 4.18 3.85 2.25 1.01 1.43 0.62 0.63 19.52
Site Type: Alfalfa Total Alfalfa ETr " 3.16 3.66 5.98 5.19 6.87 6.54 7.44 7.19 5.41 2.94 2.25 1.17 57.8
Total Growing Degee Days from March 1 0 0 164 176 362 448 588 547 408 123 101 4 2921
Gross Pond Evap Inch 2.65 3.07 5.02 4.36 5.77 5.49 6.25 6.04 4.54 2.47 1.89 0.98 48.53
Net Pond Evap Inch 2.58 3.03 4.69 1.88 4.81 2.57 3.55 4.46 3.84 1.47 1.46 0.54 34.88
 
Longmont South Avg. Temp F 35.06 37.32 42.06 46.14 58.32 62.97 68.68 68.25 61.05 41.78 39.88 22.6 48.68
Ref date as of 12/31/2009 Total Precip " 0.22 0.16 0.84 2.84 1.92 1.97 1.32 0.12 0.43 1.81 0.72 0.99 13.34
Site Type: Alfalfa Total Alfalfa ETr " 4.21 4.02 6.1 5.3 7.13 6.5 7.59 7.47 5.56 3.31 2.86 1.56 61.61
Total Growing Degee Days from March 1 0 0 149 164 333 422 569 547 390 120 122 8 2824
Gross Pond Evap Inch 3.54 3.38 5.12 4.45 5.99 5.46 6.38 6.27 4.67 2.78 2.4 1.31 51.75
Net Pond Evap Inch 3.38 3.26 4.54 2.46 4.65 4.08 5.45 6.19 4.37 1.51 1.9 0.62 42.41
 
Fort Collins NW Avg. Temp F 33.15 35.39 40.04 44.81 57.41 61.62 67.95 66.68 59.58 40.31 38.21 21.38 47.21
Ref date as of 12/31/2009 Total Precip " 0.09 0.1 0.34 2.45 1.9 4.45 3.17 0.12 0.53 0.72 0.54 0.24 14.65
Site Type: Turf Total Alfalfa ETr " 2.82 2.54 4.26 4.27 6.13 5.7 6.78 6.21 4.75 2.62 2.09 0.99 49.16
Total Growing Degee Days from March 1 0 0 130 156 322 389 552 515 383 106 106 4 2663
Gross Pond Evap Inch 2.37 2.13 3.58 3.59 5.15 4.79 5.7 5.22 3.99 2.2 1.76 0.83 41.31
Net Pond Evap Inch 2.31 2.06 3.34 1.87 3.82 1.67 3.48 5.13 3.62 1.7 1.38 0.66 31.04
 
Fort Collins Central Avg. Temp F 34.05 36.77 41.52 46.3 58.75 62.58 68.61 67.04 59.81 40.72 38.41 21.6 48.01
Ref date as of 12/31/2009 Total Precip " 0.04 0.13 0.37 2.46 1.81 4.87 3.17 0.22 0.67 1.05 0.53 0.36 15.68
Site Type: Turf Total Alfalfa ETr " 2.92 2.99 4.76 4.54 6.36 5.95 6.66 6.13 4.71 2.67 2.2 1.11 51
Total Growing Degee Days from March 1 0 0 150 175 338 415 559 527 397 122 131 9 2823
Gross Pond Evap Inch 2.45 2.51 4 3.81 5.34 5 5.59 5.15 3.96 2.24 1.85 0.93 42.83
Net Pond Evap Inch 2.42 2.42 3.74 2.09 4.08 1.59 3.38 5 3.49 1.51 1.48 0.68 31.88
 
Windsor Avg. Temp F 32.5 36.39 41.22 46.16 58.85 63.58 69.73 14.96 38.96 41.48 38.87 21.75 42.04
Ref date as of 12/27/2009 Total Precip " 0.17 0.18 0.72 4.03 2.42 2.48 3.16 0.1 1.05 1.41 0.67 0.38 16.77
Site Type: Dryland Pasture Total Alfalfa ETr " 2.63 3.08 5.02 4.66 6.32 6.04 7.18 1.13 3.06 2.68 2.02 0.83 44.65
Total Growing Degee Days from March 1 0 0 158 187 362 446 603 174 243 131 109 3 2416
Gross Pond Evap Inch 2.21 2.59 4.22 3.91 5.31 5.07 6.03 0.95 2.57 2.25 1.7 0.7 37.51
Net Pond Evap Inch 2.09 2.46 3.71 1.09 3.61 3.34 3.82 0.88 1.84 1.26 1.23 0.43 25.76
 
Greeley West Avg. Temp F 30.36 35.06 40.05 45.45 58.27 63.24 69.05 67.89 60.55 40.5 36.7 19.91 47.25
Ref date as of 12/31/2009 Total Precip " 0.04 0.05 0.24 3.16 2.19 3.17 3.64 1.32 0.87 0.69 0.26 0.08 15.71
Site Type: Turf Total Alfalfa ETr " 2.61 3.07 5.09 4.94 6.77 6.56 7.61 6.97 5.28 2.74 1.87 0.91 54.42
Total Growing Degee Days from March 1 0 0 145 171 339 441 595 553 407 111 97 3 2862
Gross Pond Evap Inch 2.19 2.58 4.28 4.15 5.69 5.51 6.39 5.85 4.44 2.3 1.57 0.76 45.71
Net Pond Evap Inch 2.16 2.54 4.11 1.94 4.15 3.29 3.84 4.93 3.83 1.82 1.39 0.71 34.71
 
Loveland Avg. Temp F 33.26 36.44 41.73 46.28 58.75 63.68 69.71 69.07 62.02 41.75 39.84 22.75 48.77
Ref date as of 12/31/2009 Total Precip " 0.04 0.17 0.32 3.27 2.29 1.99 2.1 0.99 1.18 0.8 0.45 0.41 14.01
Site Type: Turf Total Alfalfa ETr " 2.56 2.74 4.87 4.65 6.57 6.22 7.05 6.41 5.07 2.75 2.05 1.09 52.03
Total Growing Degee Days from March 1 0 0 150 177 345 435 607 586 435 128 127 7 2997
Gross Pond Evap Inch 2.15 2.3 4.09 3.91 5.52 5.22 5.92 5.38 4.26 2.31 1.72 0.92 43.7
Net Pond Evap Inch 2.12 2.18 3.87 1.62 3.92 3.83 4.45 4.69 3.43 1.75 1.41 0.63 33.9
 
Berthoud Avg. Temp F 33.64 36.58 41.02 45.48 58.02 62.85 68.78 67.5 60.31 39.76 37.87 20.68 47.71
Ref date as of 12/31/2009 Total Precip " 0.17 0.39 0.66 4.16 1.94 1.86 3.85 0.11 1.04 1.46 0.52 0.94 17.1
Site Type: Turf Total Alfalfa ETr " 3.23 3.27 5.34 4.87 6.9 6.59 7.62 7.07 5.41 2.87 2.18 1.18 56.53
Total Growing Degee Days from March 1 0 0 139 161 320 413 580 536 384 99 86 2 2720
Gross Pond Evap Inch 2.71 2.75 4.49 4.09 5.8 5.54 6.4 5.94 4.54 2.41 1.83 0.99 47.49
Net Pond Evap Inch 2.59 2.47 4.02 1.18 4.44 4.23 3.71 5.86 3.82 1.39 1.47 0.33 35.51
 
Longmont West Avg. Temp F 33.45 36.99 42.19 46.05 57.95 62.21 68.1 68.67 63.52 43.29 41.34 24.39 49.01
Ref date as of 12/31/2009 Total Precip " 0.05 0.24 0.22 3.39 1.14 2.2 2.3 0.2 0.84 1.1 0.43 0.42 12.53
Site Type: Turf Total Alfalfa ETr " 2.98 3.2 5.04 4.72 6.61 6.22 7.01 6.56 5.07 2.72 2.16 1.14 53.43
Total Growing Degee Days from March 1 0 0 139 162 319 394 552 559 449 140 143 12 2869
Gross Pond Evap Inch 2.5 2.69 4.23 3.96 5.55 5.22 5.89 5.51 4.26 2.28 1.81 0.96 44.86
Net Pond Evap Inch 2.47 2.52 4.08 1.59 4.75 3.68 4.28 5.37 3.67 1.51 1.51 0.66 36.09
 
Fort Lupton Avg. Temp F 33.95 37.3 41.75 46.25 58.91 63.4 69.18 68.74 61.46 41.75 39.7 22.44 48.74
Ref date as of 12/31/2009 Total Precip " 0.02 0 0.3 1.96 2.12 2.81 3.21 0.17 0.85 0.89 0.18 0.22 12.73
Site Type: Turf Total Alfalfa ETr " 3.75 3.99 6.02 5.39 7.68 7.22 8.43 8.51 6.33 3.53 3.3 1.64 65.79
Total Growing Degee Days from March 1 0 0 162 179 360 440 601 574 413 124 135 14 3002
Gross Pond Evap Inch 3.15 3.35 5.06 4.53 6.45 6.06 7.08 7.15 5.32 2.97 2.77 1.38 55.27
Net Pond Evap Inch 3.14 3.35 4.85 3.16 4.97 4.1 4.83 7.03 4.72 2.34 2.65 1.22 46.36
 
Boulder NW Avg. Temp F 37.23 38.77 42.65 46.67 59.03 63.89 69.81 70.05 57.07 41.96 41.67 25.26 49.51
Ref date as of 12/31/2009 Total Precip " 0.39 0.28 0.58 4.17 2.03 1.61 2.34 0.22 0.4 1.94 0.54 0.59 15.09
Site Type: Turf Total Alfalfa ETr " 3.64 3.52 5.32 4.9 6.85 6.64 7.53 7.49 5.45 3.08 2.72 1.75 58.89
Total Growing Degee Days from March 1 0 0 151 173 350 450 594 596 384 138 143 13 2992
Gross Pond Evap Inch 3.06 2.96 4.47 4.12 5.75 5.58 6.33 6.29 4.58 2.59 2.28 1.47 49.48
Net Pond Evap Inch 2.78 2.76 4.06 1.2 4.33 4.45 4.69 6.14 4.3 1.23 1.91 1.06 38.91
 
Boulder East Avg. Temp F 37.71 39.1 43.65 47.3 59.93 64.29 70.42 70.76 63.21 43.01 41.67 25.18 50.52
Ref date as of 12/31/2009 Total Precip " 0.64 0.12 0.37 4.11 2.34 1.53 2.39 0.13 0.24 1.38 0.44 0.4 14.09
Site Type: Turf Total Alfalfa ETr " 3.58 3.34 5.39 4.77 6.68 6.17 7.32 7.26 5.32 2.89 2.15 1.45 56.32
Total Growing Degee Days from March 1 0 0 153 163 342 432 599 599 424 133 125 15 2985
Gross Pond Evap Inch 3.01 2.81 4.53 4.01 5.61 5.18 6.15 6.1 4.47 2.43 1.81 1.22 47.33
Net Pond Evap Inch 2.56 2.72 4.27 1.13 3.97 4.11 4.48 6.01 4.3 1.46 1.5 0.94 37.45
 
Boulder Flatiron Avg. Temp F 35.61 37.13 41.3 45.29 57.76 62.06 67.32 66.54 59.28 41.18 38.69 23.32 47.96
Ref date as of 12/31/2009 Total Precip " 0.17 0.1 0.34 4.59 3.84 2.2 2.81 0.43 0.39 1.75 0.47 0.25 17.34
Site Type: Turf Total Alfalfa ETr " 2.83 2.82 4.46 3.88 5.22 4.58 4.99 5.04 3.67 2.14 1.78 1.28 42.69
Total Growing Degee Days from March 1 0 0 142 148 313 391 534 516 381 118 116 11 2670
Gross Pond Evap Inch 2.38 2.37 3.75 3.26 4.38 3.85 4.19 4.23 3.08 1.8 1.5 1.08 35.87
Net Pond Evap Inch 2.26 2.3 3.51 0.05 1.7 2.31 2.22 3.93 2.81 0.57 1.17 0.9 23.73
 
Boulder SW Avg. Temp F 38.68 40.18 43.86 46.73 59.4 63.65 69.84 70.25 63.32 44.04 45.06 28.19 51.1
Ref date as of 12/31/2009 Total Precip " 0.33 0.22 0.67 5.34 2.46 3.27 1.5 0.34 0.43 2.01 0.51 0.3 17.38
Site Type: Turf Total Alfalfa ETr " 4.41 3.77 5.69 4.71 6.44 5.88 6.8 6.87 5.57 3.27 2.91 2.12 58.44
Total Growing Degee Days from March 1 0 0 138 139 334 422 601 598 428 118 122 16 2916
Gross Pond Evap Inch 3.7 3.17 4.78 3.96 5.41 4.94 5.71 5.77 4.68 2.75 2.44 1.78 49.09
Net Pond Evap Inch 3.47 3.01 4.31 0.22 3.69 2.65 4.66 5.53 4.38 1.34 2.09 1.57 36.92
Greeley04 Avg. Temp F #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0! 62.77 68.83 66.8 59.48 40.16 34.97 17.61 50.09
Ref date as of 123109/0/2009 Total Precip " 0 0 0 0 0 3.44 1.89 2.65 0.75 0.63 0.2 0.01 9.57
Site Type: Fully irrigated Total Alfalfa ETr " 0 0 0 0 0 6.73 8.4 7.95 6.26 3.38 2.4 0.86 35.98
Total Growing Degee Days from March 1 0 0 0 0 0 432 582 544 409 121 98 2 2188
Gross Pond Evap Inch 0 0 0 0 0 5.65 7.06 6.68 5.26 2.84 2.02 0.72 30.23
Net Pond Evap Inch 0 0 0 0 0 3.25 5.73 4.82 4.73 2.4 1.88 0.72 23.53