Pond Evaporation Calculation 12/31/11
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 2010 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 25.69 25.91 39.3 48.91 55.67 69.93 74.56 73.58 63.18 51.23 33.93 28.51 49.2
Ref date as of 12/31/2010 Total Precip " 0.12 0.72 1.35 2.38 2.12 4.14 2.63 2.24 0.13 0.64 0.53 0.41 17.41
Site Type: Alfalfa Total Alfalfa ETr " 1.98 1.9 4.13 5.87 6.93 8.49 9.35 8.85 7.26 5.25 3.11 2.38 65.5
Total Growing Degee Days from March 1 0 0 105 201 303 566 702 658 472 287 87 31 3412
Gross Pond Evap Total " 1.66 1.6 3.47 4.93 5.82 7.13 7.85 7.43 6.1 4.41 2.61 2 55.01
Net Pond Evap Total " 1.58 1.09 2.52 3.26 4.34 4.23 6.01 5.87 6.01 3.96 2.24 1.71 42.82
Crook Avg. Temp F 25.44 26.24 39.21 48.21 54.48 68.52 72.54 72.03 62.28 51.11 34.4 29.67 48.68
Ref date as of 12/31/2010 Total Precip " 0.04 0.59 1.11 2.23 2.24 3.08 1.83 1.97 0.19 0.62 0.54 0.7 15.14
Site Type: Alfalfa Total Alfalfa ETr " 2.09 1.92 4.27 6.1 7.13 8.12 8.89 8.54 7.79 5.04 3.1 2.41 65.4
Total Growing Degee Days from March 1 0 0 107 199 285 523 654 622 479 298 93 39 3299
Gross Pond Evap Inch 1.76 1.61 3.59 5.12 5.99 6.82 7.47 7.17 6.54 4.23 2.6 2.02 54.92
Net Pond Evap Inch 1.73 1.2 2.81 3.56 4.42 4.66 6.19 5.79 6.41 3.8 2.23 1.53 44.33
 
Sterling Avg. Temp F 26.12 27.34 40.23 49.09 55.73 69.86 73.27 72.91 63.67 51.13 34.21 29.52 49.42
Ref date as of 12/31/2010 Total Precip " 0.08 0.62 1.16 2.68 2.26 2.42 2.66 3.46 0.07 1.1 0.71 0.33 17.55
Site Type: Alfalfa Total Alfalfa ETr " 1.95 2.08 4.43 6.45 7.62 8.98 9.53 9.14 7.83 4.77 2.82 2.28 67.88
Total Growing Degee Days from March 1 0 0 118 216 309 564 666 647 492 302 92 38 3444
Gross Pond Evap Inch 1.64 1.75 3.72 5.42 6.4 7.54 8.01 7.68 6.58 4.01 2.37 1.92 57.04
Net Pond Evap Inch 1.58 1.31 2.91 3.54 4.82 5.85 6.14 5.26 6.53 3.24 1.87 1.68 44.73
 
Brush Avg. Temp F 26.7 27.74 40.2 49.05 56.22 69.67 73.4 73.28 63.62 51.74 34.95 30.07 49.72
Ref date as of 12/31/2010 Total Precip " 0.03 0.27 0.64 3.05 2.25 5.75 1.05 1.79 0.09 0.91 0.39 0.2 16.42
Site Type: Alfalfa Total Alfalfa ETr " 2 2.06 4.56 6.69 8.43 8.9 8.44 8.98 7.03 5.06 3.05 2.48 67.68
Total Growing Degee Days from March 1 0 0 124 213 325 566 675 672 476 309 96 43 3499
Gross Pond Evap Inch 1.68 1.73 3.83 5.62 7.08 7.48 7.09 7.54 5.91 4.25 2.56 2.08 56.85
Net Pond Evap Inch 1.66 1.54 3.38 3.48 5.51 3.45 6.35 6.29 5.84 3.61 2.29 1.94 45.34
 
Fort Morgan Avg. Temp F 26.78 28.11 40.32 48.94 55.93 69.07 73.41 72.98 64.73 52.78 35.63 31.05 49.98
Ref date as of 12/31/2010 Total Precip " 0.05 0.36 0.85 3.84 2.01 4.87 1.43 3.97 0.12 0.54 0.45 0.42 18.91
Site Type: Turf Total Alfalfa ETr " 1.87 1.94 4.09 5.84 7.46 8.14 8.74 8.25 7.02 4.71 2.57 2.23 62.86
Total Growing Degee Days from March 1 0 0 121 204 314 550 672 666 498 320 99 46 3490
Gross Pond Evap Inch 1.57 1.63 3.44 4.91 6.27 6.84 7.34 6.93 5.9 3.96 2.16 1.87 52.82
Net Pond Evap Inch 1.54 1.38 2.84 2.22 4.86 3.43 6.34 4.15 5.81 3.58 1.84 1.58 39.57
 
Wiggins Avg. Temp F 26.35 27.6 39.85 48.09 55.35 68.94 73.18 73.11 64.36 52.38 34.66 29.88 49.48
Ref date as of 12/31/2010 Total Precip " 0.04 0.37 0.44 2.6 1.75 2.68 1.43 0.72 0.06 0.78 1.87 0.2 12.94
Site Type: Alfalfa Total Alfalfa ETr " 1.95 2.05 4.51 6.44 8.18 8.93 9.66 9.79 8.07 5.46 3.03 2.67 70.74
Total Growing Degee Days from March 1 0 0 116 200 310 541 663 659 492 321 93 43 3438
Gross Pond Evap Inch 1.64 1.72 3.79 5.41 6.87 7.5 8.11 8.22 6.78 4.59 2.55 2.24 59.42
Net Pond Evap Inch 1.61 1.46 3.48 3.59 5.65 5.63 7.11 7.72 6.74 4.04 1.24 2.1 50.37
 
Fort Collins East Avg. Temp F 26.38 27.14 39.35 46.26 53.09 66.68 70.24 68.49 61.34 51.18 34.15 30.77 47.92
Ref date as of 12/31/2010 Total Precip " 0.01 0.23 0.7 4 1.87 1.37 1.28 0.79 0.11 0.8 0.89 0.17 12.22
Site Type: Alfalfa Total Alfalfa ETr " 1.67 1.8 4.47 5.62 6.85 8.08 8.45 7.11 6.97 4.64 2.54 2.45 60.65
Total Growing Degee Days from March 1 0 0 108 152 260 490 592 574 444 268 72 37 2997
Gross Pond Evap Inch 1.4 1.51 3.75 4.72 5.75 6.79 7.1 5.97 5.85 3.9 2.13 2.06 50.93
Net Pond Evap Inch 1.4 1.35 3.26 1.92 4.45 5.83 6.2 5.42 5.78 3.34 1.51 1.94 42.4
 
Eaton Avg. Temp F 24.93 25.95 39.22 46.93 54.15 67.21 70.59 69.87 62.31 51.88 34.09 30.43 48.13
Ref date as of 12/31/2010 Total Precip " 0.09 0.59 0.68 3.15 2.25 2.04 3.72 1.44 0.07 0.65 0.93 0.25 15.86
Site Type: Alfalfa Total Alfalfa ETr " 1.56 1.85 4.34 5.93 7.77 8.26 8.5 7.82 7.12 4.76 2.54 2.49 62.94
Total Growing Degee Days from March 1 0 0 102 172 290 504 607 609 459 288 73 39 3143
Gross Pond Evap Inch 1.31 1.55 3.65 4.98 6.53 6.94 7.14 6.57 5.98 4 2.13 2.09 52.87
Net Pond Evap Inch 1.25 1.14 3.17 2.78 4.95 5.51 4.54 5.56 5.93 3.54 1.48 1.92 41.77
 
Johnsons Corner Avg. Temp F 26.1 27.23 39.74 46.53 52.62 66.97 70.89 70.4 63.66 53.56 36.64 32.95 48.94
Ref date as of 12/31/2010 Total Precip " 0.23 0.53 1.02 3.53 2.12 1.73 2.34 0.44 0.13 0.57 0.83 0.26 13.73
Site Type: Alfalfa Total Alfalfa ETr " 1.69 1.61 4.27 5.21 6.16 7.88 8.31 8.11 7.07 4.62 2.54 2.5 59.97
Total Growing Degee Days from March 1 0 0 102 150 254 499 608 614 459 291 87 44 3108
Gross Pond Evap Inch 1.42 1.35 3.59 4.38 5.17 6.62 6.98 6.81 5.94 3.88 2.13 2.1 50.37
Net Pond Evap Inch 1.26 0.98 2.87 1.91 3.69 5.41 5.34 6.5 5.85 3.48 1.55 1.92 40.76
 
Gilcrest Avg. Temp F 23.42 27.09 39.46 47.08 53.75 67.78 71.54 70.51 62.2 51.02 34.12 29.68 48.14
Ref date as of 12/31/2010 Total Precip " 0.07 0.45 0.79 3.08 2.02 2.1 0.41 1.39 0.11 0.49 0.8 0.1 11.81
Site Type: Alfalfa Total Alfalfa ETr " 1.34 1.57 4.18 5.55 7.14 8.17 8.43 7.78 6.76 4.21 2.4 2.29 59.82
Total Growing Degee Days from March 1 0 0 104 169 286 515 614 619 464 294 82 34 3181
Gross Pond Evap Inch 1.13 1.32 3.51 4.66 6 6.86 7.08 6.54 5.68 3.54 2.02 1.92 50.26
Net Pond Evap Inch 1.08 1 2.96 2.51 4.58 5.39 6.79 5.56 5.6 3.19 1.46 1.85 41.97
 
Longmont South Avg. Temp F 27.64 28.08 40.84 47.69 53.65 67.71 71.44 71.43 63.88 53.68 37.25 34.07 49.78
Ref date as of 12/31/2010 Total Precip " 0.37 0.8 1.22 2.99 1.68 1.8 1.1 0.67 0.13 0.89 0.6 0.37 12.62
Site Type: Alfalfa Total Alfalfa ETr " 1.78 1.66 4.22 5.55 6.74 7.77 8.14 8.12 6.98 4.76 2.71 2.79 61.22
Total Growing Degee Days from March 1 0 0 105 155 259 501 619 625 452 287 90 56 3149
Gross Pond Evap Inch 1.5 1.39 3.54 4.66 5.66 6.53 6.84 6.82 5.86 4 2.28 2.34 51.42
Net Pond Evap Inch 1.24 0.83 2.69 2.57 4.49 5.27 6.07 6.35 5.77 3.38 1.86 2.08 42.6
 
Fort Collins NW Avg. Temp F 26.75 27.07 39.75 46.19 52.76 66.22 70.68 69.97 62.22 51.28 35.03 32 48.33
Ref date as of 12/31/2010 Total Precip " 0.15 0.39 0.93 2.6 1.93 1.93 0.84 0.52 0.03 0.72 0.46 0.01 10.51
Site Type: Turf Total Alfalfa ETr " 1.34 1.4 3.72 4.7 2.29 1.21 0.73 -0.95 -2.02 -2.41 -2.59 -3.2 15.39
Total Growing Degee Days from March 1 0 0 97 138 247 477 594 597 442 258 67 30 2947
Gross Pond Evap Inch 1.13 1.18 3.12 3.95 1.92 1.02 0.61 0 0 0 0 0 12.93
Net Pond Evap Inch 1.02 0.9 2.47 2.13 0.57 0 0.03 0 0 0 0 0 7.12
 
Fort Collins Central Avg. Temp F 26.72 27.74 40.18 46.92 53.98 67.38 71.73 70.82 62.54 51.35 35.2 32.04 48.88
Ref date as of 12/31/2010 Total Precip " 0.16 0.38 1.1 2.8 1.89 2.02 1.27 1.13 0.04 1.01 0.7 0.02 12.52
Site Type: Turf Total Alfalfa ETr " 1.37 1.49 3.72 4.76 6.07 6.71 7.26 6.68 5.41 3.47 2 1.78 50.72
Total Growing Degee Days from March 1 0 0 102 146 268 504 618 621 459 279 80 39 3116
Gross Pond Evap Inch 1.15 1.25 3.12 4 5.1 5.64 6.1 5.61 4.54 2.91 1.68 1.5 42.6
Net Pond Evap Inch 1.04 0.99 2.35 2.04 3.78 4.22 5.21 4.82 4.52 2.21 1.19 1.48 33.85
 
Windsor Avg. Temp F 27.36 28.47 40.76 47.54 54.3 68.11 72.94 72.42 65.29 53.66 36.32 21.85 49.09
Ref date as of 12/31/2010 Total Precip " 0.21 0.51 1.06 3.43 2.32 1.33 1.05 0.33 0.04 0.51 1.03 0.17 11.99
Site Type: Dryland Pasture Total Alfalfa ETr " 1.16 1.39 3.5 4.69 6.07 6.81 7.87 6.81 5.55 3.2 1.76 1.22 50.03
Total Growing Degee Days from March 1 0 0 115 182 297 532 643 649 490 314 91 35 3348
Gross Pond Evap Inch 0.97 1.17 2.94 3.94 5.1 5.72 6.61 5.72 4.66 2.69 1.48 1.02 42.02
Net Pond Evap Inch 0.83 0.81 2.2 1.54 3.47 4.79 5.88 5.49 4.63 2.33 0.76 0.91 33.64
 
Greeley West Avg. Temp F 25.41 27.3 39.68 47.04 53.98 67.97 72.18 71.55 63.53 52.24 34.7 30.48 48.84
Ref date as of 12/31/2010 Total Precip " 0.05 0.32 0.46 3.88 2.12 2.24 1.86 1.15 0.07 0.38 0.82 0 13.35
Site Type: Turf Total Alfalfa ETr " 1.13 1.5 3.78 5.45 7.03 7.81 8.31 7.86 6.26 4.02 1.98 1.86 56.99
Total Growing Degee Days from March 1 0 0 97 162 277 521 639 639 467 293 75 32 3202
Gross Pond Evap Inch 0.95 1.26 3.18 4.58 5.91 6.56 6.98 6.6 5.26 3.38 1.66 1.56 47.88
Net Pond Evap Inch 0.91 1.04 2.85 1.86 4.42 4.99 5.68 5.8 5.21 3.11 1.09 1.56 38.52
 
Loveland Avg. Temp F 27.31 28.1 41.11 47.96 54.41 68.33 72.92 72.03 64.06 53.26 36.64 32.76 49.91
Ref date as of 12/31/2010 Total Precip " 0.17 0.24 0.68 2.99 1.79 1.89 2.51 0.72 0.05 0.49 0.53 0 12.06
Site Type: Turf Total Alfalfa ETr " 1.3 1.46 3.8 4.97 6.38 7.41 8 7.28 6 3.86 2.02 1.85 54.33
Total Growing Degee Days from March 1 0 0 115 166 286 537 662 657 482 302 91 40 3338
Gross Pond Evap Inch 1.09 1.23 3.19 4.17 5.36 6.22 6.72 6.12 5.04 3.24 1.7 1.55 45.63
Net Pond Evap Inch 0.97 1.06 2.72 2.08 4.11 4.9 4.96 5.61 5.01 2.9 1.33 1.55 37.2
 
Berthoud Avg. Temp F 26.02 26.48 38.91 45.89 52.23 66.43 70.84 70.38 63.58 52.5 36.03 32.81 48.51
Ref date as of 12/31/2010 Total Precip " 0.23 0.61 1.37 3.27 2.01 1.54 1.83 0.29 0.08 0.52 0.6 0.28 12.63
Site Type: Turf Total Alfalfa ETr " 1.45 1.5 3.82 5.03 6.39 7.45 7.72 7.5 6.57 4.08 2.24 2.22 55.97
Total Growing Degee Days from March 1 0 0 90 135 244 497 611 611 449 256 75 33 3001
Gross Pond Evap Inch 1.22 1.26 3.21 4.23 5.37 6.26 6.48 6.3 5.52 3.43 1.88 1.86 47.02
Net Pond Evap Inch 1.06 0.83 2.25 1.94 3.96 5.18 5.2 6.1 5.46 3.06 1.46 1.67 38.17
 
Longmont West Avg. Temp F 28.9 29.55 42.29 49.73 55.97 70.16 74.66 73.79 65.73 54.5 38.07 35.09 51.54
Ref date as of 12/31/2010 Total Precip " 0.16 0.47 1.19 3.08 1.76 1.7 1.18 0.74 0.1 0.64 0.7 0 11.72
Site Type: Turf Total Alfalfa ETr " 1.34 1.44 3.67 5.08 6.32 6.94 7.42 6.77 5.55 3.49 2 1.96 51.98
Total Growing Degee Days from March 1 0 0 116 180 295 562 688 685 479 299 95 55 3454
Gross Pond Evap Inch 1.13 1.21 3.08 4.27 5.31 5.83 6.23 5.69 4.66 2.93 1.68 1.65 43.67
Net Pond Evap Inch 1.01 0.88 2.25 2.11 4.08 4.64 5.41 5.17 4.59 2.48 1.19 1.65 35.46
 
Fort Lupton Avg. Temp F 27.49 28.47 40.48 47.5 54.17 68.1 72.55 72.19 64.95 54.01 37.44 33.56 50.08
Ref date as of 12/31/2010 Total Precip " 0.05 0.21 0.47 2.56 2.33 2.81 0.91 1.24 0.38 0.8 0.55 0.01 12.32
Site Type: Turf Total Alfalfa ETr " 1.95 1.97 4.54 6.07 7.7 8.79 9.46 8.93 7.79 4.94 2.66 2.52 67.32
Total Growing Degee Days from March 1 0 0 100 168 277 523 654 653 470 298 86 50 3279
Gross Pond Evap Inch 1.64 1.65 3.81 5.1 6.47 7.38 7.95 7.5 6.54 4.15 2.23 2.12 56.54
Net Pond Evap Inch 1.6 1.51 3.48 3.31 4.84 5.42 7.31 6.63 6.28 3.59 1.85 2.11 47.93
 
Boulder NW Avg. Temp F 30.64 28.4 40.4 46.97 53.3 67.83 72.55 72.28 65.27 53.67 38.71 35.41 50.45
Ref date as of 12/31/2010 Total Precip " 0.26 0.8 1.79 4.35 2.8 2.45 2.13 0.61 0.2 0.82 0.52 0.09 16.82
Site Type: Turf Total Alfalfa ETr " 1.97 1.74 3.96 5.06 6.41 7.28 8.23 8.26 6.78 4.33 2.47 2.24 58.73
Total Growing Degee Days from March 1 0 0 107 159 265 515 646 650 489 292 99 61 3283
Gross Pond Evap Inch 1.65 1.46 3.33 4.25 5.38 6.12 6.91 6.94 5.7 3.64 2.07 1.88 49.33
Net Pond Evap Inch 1.47 0.9 2.07 1.21 3.42 4.4 5.42 6.51 5.56 3.06 1.71 1.82 37.55
 
Boulder East Avg. Temp F 29.67 29 42.01 48.78 44.85 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 38.86
Ref date as of 5/2/2010 Total Precip " 0.17 0.95 1.39 2.94 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 5.45
Site Type: Turf Total Alfalfa ETr " 1.42 1.55 3.91 5.26 0.34 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 12.48
Total Growing Degee Days from March 1 0 0 106 157 5 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 268
Gross Pond Evap Inch 1.19 1.3 3.28 4.42 0.29 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 10.48
Net Pond Evap Inch 1.07 0.64 2.31 2.36 0.29 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 6.67
 
Boulder Flatiron Avg. Temp F 27.35 27.1 39.63 46.87 42.6 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 36.71
Ref date as of 5/2/2010 Total Precip " 0.12 0.41 1.57 3.08 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 5.18
Site Type: Turf Total Alfalfa ETr " 1.34 1.32 3.2 4.41 0.28 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 10.55
Total Growing Degee Days from March 1 0 0 95 144 4 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 243
Gross Pond Evap Inch 1.13 1.11 2.69 3.7 0.24 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 8.87
Net Pond Evap Inch 1.04 0.82 1.59 1.55 0.24 #N/A #N/A #N/A #N/A #N/A #N/A #N/A 5.24
 
Boulder SW Avg. Temp F 33.83 30.62 42.54 48.53 54.28 68.3 73.38 72.96 66.93 54.79 39.86 36.82 51.9
Ref date as of 12/31/2010 Total Precip " 0.22 0.83 1.78 3.36 2.81 2.45 2.27 1.1 0.28 0.94 0.48 0.25 16.77
Site Type: Turf Total Alfalfa ETr " 2.07 1.73 4.05 5.13 6.35 6.88 7.22 7.68 6.64 4.37 2.72 2.59 57.43
Total Growing Degee Days from March 1 0 0 92 140 249 516 665 672 476 253 79 52 3194
Gross Pond Evap Inch 1.74 1.45 3.4 4.31 5.33 5.78 6.06 6.45 5.58 3.67 2.28 2.18 48.23
Net Pond Evap Inch 1.58 0.87 2.16 1.96 3.37 4.06 4.48 5.68 5.38 3.01 1.95 2 36.5
Greeley04 Avg. Temp F 25.04 26.96 39.13 47 54.31 67.84 71.44 70.47 62.94 51.73 33.57 30.28 48.39
Ref date as of 123110/0/2010 Total Precip " 0.03 0.26 0.28 3.32 1.97 3.17 1.64 1.63 0.01 0.55 0.34 0.01 13.21
Site Type: Fully irrigated Total Alfalfa ETr " 1.46 1.94 4.54 6.57 8.6 9.1 8.23 7.4 6.78 4.42 2.41 2.31 63.76
Total Growing Degee Days from March 1 0 0 106 182 297 525 608 623 474 298 77 36 3226
Gross Pond Evap Inch 1.23 1.63 3.81 5.52 7.22 7.64 6.91 6.22 5.7 3.71 2.02 1.94 53.55
Net Pond Evap Inch 1.21 1.45 3.62 3.19 5.85 5.43 5.77 5.08 5.69 3.33 1.79 1.93 44.34