Pond Evaporation Calculation 12/28/20
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 2020 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 30.15 30.43 40.88 46.44 57.85 73.43 75.01 74.49 61.51 44.6 39.8 31.53 50.51
Ref date as of 122820//2020 Total Precip " 0.35 0.28 1.27 0.54 2.97 1.52 1.5 0.51 0.76 0.19 0.29 0.2 10.38
Site Type: Alfalfa Total Alfalfa ETr " 2.35 2.96 4.15 7.13 7.59 11.48 10.08 9.25 6.45 4.41 3.18 1.94 70.97
Total Growing Degee Days from March 1 0 0 129 242 340 609 707 665 427 251 169 60 3599
Gross Pond Evap Total " 1.97 2.49 3.49 5.99 6.38 9.64 8.47 7.77 5.42 3.7 2.67 1.63 59.62
Net Pond Evap Total " 1.73 2.29 2.6 5.61 4.3 8.58 7.42 7.41 4.89 3.57 2.47 1.49 52.36
Crook Avg. Temp F 30.71 29.8 40 45.96 57.35 71.98 74.31 74.37 60.64 44.25 39.28 31.48 50.01
Ref date as of 122820//2020 Total Precip " 0.11 0.23 1.1 0.4 1.82 2.01 1.72 0.44 0.89 0.34 0.26 0.25 9.57
Site Type: Alfalfa Total Alfalfa ETr " 2.4 2.76 3.79 6.49 7.29 10.61 8.75 8.06 5.65 4.05 2.92 1.97 64.74
Total Growing Degee Days from March 1 0 0 124 235 337 580 685 658 425 260 166 64 3534
Gross Pond Evap Inch 2.02 2.32 3.18 5.45 6.12 8.91 7.35 6.77 4.75 3.4 2.45 1.65 54.37
Net Pond Evap Inch 1.94 2.16 2.41 5.17 4.85 7.51 6.15 6.46 4.12 3.16 2.27 1.48 47.68
 
Sterling Avg. Temp F 31.77 29.68 40.89 46.59 58.57 72.21 74.53 74.87 60.41 44.52 38.92 28.94 50.16
Ref date as of 122820//2020 Total Precip " 0.09 0.15 0.79 0.35 2.59 1.69 2.6 0.46 1.03 0.17 0.25 0.36 10.53
Site Type: Alfalfa Total Alfalfa ETr " 2.37 2.54 3.8 6.33 7.54 10.26 9.25 8.63 5.75 4.26 2.9 1.59 65.22
Total Growing Degee Days from March 1 0 0 134 234 361 582 691 673 416 261 153 49 3554
Gross Pond Evap Inch 1.99 2.13 3.19 5.32 6.33 8.62 7.77 7.25 4.83 3.58 2.44 1.34 54.79
Net Pond Evap Inch 1.93 2.03 2.64 5.07 4.52 7.44 5.95 6.93 4.11 3.46 2.26 1.08 47.42
 
Brush Avg. Temp F 31.07 28.82 40.45 46.1 58.43 70.56 73.39 72.93 59.12 44.25 37.1 27.13 49.11
Ref date as of 122820//2020 Total Precip " 0.14 0.24 1.06 0.43 1.68 2.09 1.09 2.22 1.04 0.3 0.55 0.45 11.29
Site Type: Alfalfa Total Alfalfa ETr " 2.27 2.35 3.85 6.02 7.56 9.71 8.81 7.69 5.35 4.22 2.8 1.42 62.05
Total Growing Degee Days from March 1 0 0 140 241 381 546 647 634 423 273 154 40 3479
Gross Pond Evap Inch 1.91 1.97 3.23 5.06 6.35 8.16 7.4 6.46 4.49 3.54 2.35 1.19 52.11
Net Pond Evap Inch 1.81 1.81 2.49 4.76 5.17 6.69 6.64 4.91 3.77 3.33 1.97 0.88 44.23
 
Fort Morgan Avg. Temp F 32.04 29.36 40.7 46.48 59.45 71.33 74.14 74.03 60.63 44.52 38.04 28.31 49.92
Ref date as of 122820//2020 Total Precip " 0.25 0.36 1.44 1.32 1.83 2.28 0.73 1.82 1.04 0.17 0.44 0.29 11.97
Site Type: Turf Total Alfalfa ETr " 2.17 2.28 3.69 5.73 7.61 9.47 8.71 7.85 5.37 3.67 2.56 1.51 60.62
Total Growing Degee Days from March 1 0 0 131 231 401 571 685 672 425 269 146 41 3572
Gross Pond Evap Inch 1.82 1.92 3.1 4.81 6.39 7.95 7.32 6.59 4.51 3.08 2.15 1.27 50.91
Net Pond Evap Inch 1.65 1.66 2.09 3.89 5.11 6.36 6.81 5.32 3.78 2.96 1.84 1.07 42.54
 
Wiggins Avg. Temp F 31.87 29.27 39.9 45.96 59.02 71.02 74.05 73.25 59.72 43.63 36.83 27.48 49.33
Ref date as of 122820//2020 Total Precip " 0.08 0.13 1.5 0.61 1.6 0.98 0.55 0.53 0.76 0.19 0.39 0.4 7.72
Site Type: Alfalfa Total Alfalfa ETr " 2.22 2.46 3.87 6.15 7.91 10.11 9.65 8.48 5.62 3.94 2.68 1.5 64.59
Total Growing Degee Days from March 1 0 0 137 230 384 565 664 647 418 268 139 41 3493
Gross Pond Evap Inch 1.86 2.07 3.25 5.17 6.64 8.49 8.11 7.12 4.72 3.31 2.25 1.26 54.25
Net Pond Evap Inch 1.81 1.98 2.2 4.74 5.52 7.81 7.72 6.75 4.19 3.18 1.98 0.98 48.86
 
Fort Collins East Avg. Temp F 32.81 28.01 39.55 44.35 57.43 68.63 72.25 70.94 58.85 44.21 39.49 31.26 48.98
Ref date as of 122820//2020 Total Precip " 0.02 0.47 0.97 1.19 2.11 1.23 0.16 0.21 0.75 6.64 0.51 12.27 26.53
Site Type: Alfalfa Total Alfalfa ETr " 2.48 2.44 4.07 5.86 6.91 8.69 8.77 7.52 5.22 3.99 2.73 1.88 60.56
Total Growing Degee Days from March 1 0 0 119 198 348 531 628 596 397 233 133 53 3236
Gross Pond Evap Inch 2.08 2.05 3.42 4.92 5.8 7.3 7.37 6.32 4.38 3.35 2.29 1.58 50.86
Net Pond Evap Inch 2.07 1.72 2.74 4.09 4.33 6.44 7.25 6.17 3.86 0 1.94 0 40.61
 
Eaton Avg. Temp F 31.36 27.63 38.9 44.4 57.94 68.79 71.7 70.82 59.1 43.55 38.53 30.35 48.59
Ref date as of 122820//2020 Total Precip " 0.01 0.36 1.16 0.83 1.02 1.24 0.33 1.04 0.59 0.6 0.27 0.23 7.68
Site Type: Alfalfa Total Alfalfa ETr " 2 2.23 3.93 6.07 8.12 9.2 8.69 7.17 5.22 3.94 2.59 1.71 60.87
Total Growing Degee Days from March 1 0 0 112 207 370 531 624 610 413 252 126 50 3295
Gross Pond Evap Inch 1.68 1.87 3.3 5.1 6.82 7.73 7.3 6.02 4.38 3.31 2.18 1.44 51.13
Net Pond Evap Inch 1.67 1.62 2.49 4.52 6.11 6.86 7.07 5.29 3.97 2.89 1.99 1.28 45.76
 
Johnsons Corner Avg. Temp F 33.56 28.03 40.67 45.35 57.79 69.2 72.99 73.05 62.5 47.41 42.05 33.11 50.48
Ref date as of 122820//2020 Total Precip " 0.05 0.93 1.4 1.67 2.19 1.74 0.24 0.16 0.93 0.62 0.33 0.35 10.61
Site Type: Alfalfa Total Alfalfa ETr " 2.23 2.02 3.86 5.45 6.83 8.73 9.08 7.94 5.51 4.16 2.73 1.76 60.3
Total Growing Degee Days from March 1 0 0 100 192 350 542 668 651 421 248 142 52 3366
Gross Pond Evap Inch 1.87 1.7 3.24 4.58 5.74 7.33 7.63 6.67 4.63 3.49 2.29 1.48 50.65
Net Pond Evap Inch 1.84 1.05 2.26 3.41 4.2 6.12 7.46 6.56 3.98 3.06 2.06 1.23 43.23
 
Gilcrest Avg. Temp F 31.96 25.6 40.16 45.27 59.26 70.27 72.97 72.22 60.01 44.19 37.94 27.3 48.93
Ref date as of 122820//2020 Total Precip " 0.05 0.78 1.92 1.18 1.13 2.17 1.01 1.23 0.8 1.36 0.24 0.36 12.23
Site Type: Alfalfa Total Alfalfa ETr " 2.03 1.89 3.82 5.64 7.76 9.26 9.13 8.18 5.34 3.8 2.49 1.44 60.78
Total Growing Degee Days from March 1 0 0 115 214 385 554 650 625 416 258 144 44 3405
Gross Pond Evap Inch 1.71 1.59 3.21 4.74 6.52 7.78 7.67 6.87 4.49 3.19 2.09 1.21 51.07
Net Pond Evap Inch 1.67 1.04 1.86 3.91 5.73 6.26 6.96 6.01 3.93 2.24 1.92 0.96 42.49
 
Longmont South Avg. Temp F 34.49 28.16 41.69 45.8 58.28 68.92 71.89 71.3 60.67 46.27 40.96 32.02 50.04
Ref date as of 122820//2020 Total Precip " 0.12 0.97 1.6 1.43 1.84 2.03 0.48 0.22 0.95 0.68 0.36 0.28 10.96
Site Type: Alfalfa Total Alfalfa ETr " 2.6 2.22 4.1 5.78 7.11 8.68 8.06 7 5.06 3.75 2.77 1.76 58.89
Total Growing Degee Days from March 1 0 0 117 198 353 526 621 599 417 246 141 60 3278
Gross Pond Evap Inch 2.18 1.86 3.44 4.86 5.97 7.29 6.77 5.88 4.25 3.15 2.33 1.48 49.46
Net Pond Evap Inch 2.1 1.19 2.32 3.85 4.68 5.87 6.43 5.73 3.59 2.67 2.07 1.28 41.78
 
Fort Collins NW Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Ref date as of 12/31/2010 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
 
Fort Collins Central Avg. Temp F 33.69 29.06 40.35 46.07 58.57 68.78 72.85 71.74 59.15 44.33 39.12 30.99 49.56
Ref date as of 122820//2020 Total Precip " 0.01 0.36 1.18 1.2 2.21 1.44 0.35 0.18 1.14 0.46 0.58 0.18 9.29
Site Type: Turf Total Alfalfa ETr " 2.14 2.16 3.63 5.21 6.49 7.5 7.7 6.48 4.53 3.28 2.52 1.62 53.26
Total Growing Degee Days from March 1 0 0 117 207 358 524 622 601 409 247 135 57 3277
Gross Pond Evap Inch 1.8 1.81 3.05 4.38 5.45 6.3 6.47 5.44 3.81 2.76 2.12 1.36 44.75
Net Pond Evap Inch 1.79 1.56 2.22 3.54 3.9 5.29 6.22 5.32 3.01 2.43 1.71 1.23 38.22
 
Windsor Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Ref date as of 7/1/2012 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Site Type: Dryland Pasture Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
 
Greeley West Avg. Temp F 33.48 29.28 41.55 46.88 60.16 71.49 75.5 75.05 62.43 46.17 40.53 31.73 51.19
Ref date as of 122820//2020 Total Precip " 0.05 0.59 1.64 1.61 1.06 1.07 0.18 6.61 0.8 0.51 0.29 2.54 16.95
Site Type: Turf Total Alfalfa ETr " 1.99 2.1 3.74 5.45 7.38 8.19 8.48 7.08 4.86 3.25 2.29 1.49 56.3
Total Growing Degee Days from March 1 0 0 133 233 396 581 698 676 444 263 143 60 3627
Gross Pond Evap Inch 1.67 1.76 3.14 4.58 6.2 6.88 7.12 5.95 4.08 2.73 1.92 1.25 47.28
Net Pond Evap Inch 1.64 1.35 1.99 3.45 5.46 6.13 7 1.32 3.52 2.37 1.72 0 35.95
 
Loveland Avg. Temp F 34.04 29.53 41.75 46.69 59.74 70.41 74.1 73.59 60.88 45.62 40.26 31.43 50.67
Ref date as of 122820//2020 Total Precip " 0 1.15 1.62 2.07 2.54 2.25 0.39 0.37 1.04 0.82 0.46 0.29 13
Site Type: Turf Total Alfalfa ETr " 2.1 2.11 3.68 5.17 6.74 7.81 7.76 6.71 4.66 3.35 1.54 1.46 53.09
Total Growing Degee Days from March 1 0 0 141 225 397 575 684 663 438 267 163 75 3628
Gross Pond Evap Inch 1.76 1.77 3.09 4.34 5.66 6.56 6.52 5.64 3.91 2.81 1.29 1.23 44.58
Net Pond Evap Inch 1.76 0.97 1.96 2.89 3.88 4.99 6.25 5.38 3.19 2.24 0.97 1.02 35.5
 
Berthoud Avg. Temp F 33.68 28.3 40.9 45.83 58.54 69.59 73.47 74.12 62.58 47.25 41.75 32.37 50.7
Ref date as of 122820//2020 Total Precip " 0 0.85 1.47 1.85 2.11 5.04 0.33 0.12 0.9 0.54 0.3 0.29 13.8
Site Type: Turf Total Alfalfa ETr " 2.25 2.03 3.75 5.4 7.02 8.52 8.54 7.96 5.34 3.85 2.58 1.66 58.9
Total Growing Degee Days from March 1 0 0 106 201 367 555 678 679 439 253 139 51 3468
Gross Pond Evap Inch 1.89 1.71 3.15 4.54 5.9 7.16 7.17 6.69 4.49 3.23 2.17 1.39 49.49
Net Pond Evap Inch 1.89 1.11 2.12 3.24 4.42 3.63 6.94 6.6 3.86 2.86 1.96 1.19 39.82
 
Longmont West Avg. Temp F 34.91 29.52 42.15 46.84 59.8 70.51 74.34 74.02 62.27 47.07 41.36 31.66 51.2
Ref date as of 122820//2020 Total Precip " 0 0.74 1.41 1.01 2.14 1.85 1.67 0.52 1.15 0.22 0.16 0.24 11.11
Site Type: Turf Total Alfalfa ETr " 2.17 2.05 3.57 5.11 6.85 7.69 7.68 6.69 4.77 3.31 2.5 1.49 53.88
Total Growing Degee Days from March 1 0 0 0 0 0 0 0 0 0 0 0 0 0
Gross Pond Evap Inch 1.82 1.72 3 4.29 5.75 6.46 6.45 5.62 4.01 2.78 2.1 1.25 45.25
Net Pond Evap Inch 1.82 1.2 2.01 3.59 4.26 5.16 5.28 5.26 3.2 2.63 1.99 1.08 37.48
 
Fort Lupton Avg. Temp F 33.88 28.32 41.41 46.31 59.16 70.83 74.68 74.84 63.15 47.71 41.9 32.41 51.22
Ref date as of 122820//2020 Total Precip " 0.3 0.97 1.87 0.69 1.24 0.93 0.31 0.19 0.72 0.52 0.4 0.39 8.53
Site Type: Turf Total Alfalfa ETr " 2.35 2.21 4.08 5.74 7.94 10.01 9.9 9.1 6.11 4.3 3.05 1.77 66.56
Total Growing Degee Days from March 1 0 0 113 207 381 577 694 681 460 268 157 55 3593
Gross Pond Evap Inch 1.97 1.86 3.43 4.82 6.67 8.41 8.32 7.64 5.13 3.61 2.56 1.49 55.91
Net Pond Evap Inch 1.76 1.18 2.12 4.34 5.8 7.76 8.1 7.51 4.63 3.25 2.28 1.21 49.94
 
Boulder NW Avg. Temp F 35.72 30.41 42.12 46.5 58.55 70.01 74.12 74.24 63.43 48.28 42.99 35.75 51.84
Ref date as of 122820//2020 Total Precip " 0.03 1.7 2.34 1.63 1.63 2.04 0.62 0.49 1.22 0.49 0.74 0.33 13.26
Site Type: Turf Total Alfalfa ETr " 2.49 2.37 3.9 5.48 6.92 8.22 8.11 7.44 5.55 3.59 1.66 1.11 56.84
Total Growing Degee Days from March 1 0 0 111 201 353 540 660 661 444 262 144 65 3441
Gross Pond Evap Inch 2.09 1.99 3.28 4.6 5.81 6.9 6.81 6.25 4.66 3.02 1.39 0.93 47.73
Net Pond Evap Inch 2.07 0.8 1.64 3.46 4.67 5.48 6.38 5.91 3.81 2.67 0.88 0.7 38.47
 
Boulder East Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Ref date as of 5/2/2010 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
 
Boulder Flatiron Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Ref date as of 5/2/2010 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A #N/A 0
 
Boulder SW Avg. Temp F 37.82 32.34 43.13 47.56 59.03 70.27 74.65 74.8 64.83 50.38 45.34 37.53 53.14
Ref date as of 122820//2020 Total Precip " 0 0 0 0 0.19 2.19 0.7 0.46 1.36 0.41 0.67 0.32 6.3
Site Type: Turf Total Alfalfa ETr " 2.78 2.58 3.88 5.35 6.4 8.03 7.86 7.14 5.44 3.99 3.1 2.17 58.72
Total Growing Degee Days from March 1 0 0 101 186 344 533 678 644 443 280 139 53 3401
Gross Pond Evap Inch 2.34 2.17 3.26 4.49 5.38 6.75 6.6 6 4.57 3.35 2.6 1.82 49.33
Net Pond Evap Inch 2.34 2.17 3.26 4.49 5.24 5.21 6.11 5.68 3.62 3.06 2.14 1.6 44.92
Greeley04 Avg. Temp F 31.69 28.86 39.6 45.79 59.15 70.29 73.2 72.13 60.18 43.75 38.13 27.76 49.21
Ref date as of 12/31/2020 Total Precip " 0 0.11 1.3 0.34 1.18 1.1 0.21 0.77 0.43 0.04 0.06 0.18 5.72
Site Type: Fully irrigated Total Alfalfa ETr " 2.45 2.49 4.2 6.35 9.28 9.8 9.57 7.9 5.93 4.16 2.86 2.18 67.17
Total Growing Degee Days from March 1 0 0 122 222 392 577 658 633 421 245 130 52 3452
Gross Pond Evap Inch 2.06 2.09 3.53 5.33 7.8 8.23 8.04 6.64 4.98 3.49 2.4 1.83 56.42
Net Pond Evap Inch 2.06 2.01 2.62 5.1 6.97 7.46 7.89 6.1 4.68 3.47 2.36 1.71 52.43