Pond Evaporation Calculation 1/31/22
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 2021 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 28.9 18.32 40.2 46.02 56.74 72.16 75.61 72.96 65.54 50.09 40.32 31.75 49.88
Ref date as of 12/31/2021 Total Precip " 0.17 0.41 2.88 1.46 3.68 1.3 0.28 3.83 2.13 0.66 0.34 0.22 17.36
Site Type: Alfalfa Total Alfalfa ETr " 1.95 1.69 4.27 5.98 5.8 8.87 9.13 7.78 6.02 4.51 3.05 2.48 61.53
Total Growing Degee Days from March 1 0 0 129 209 305 604 705 664 505 290 165 84 3660
Gross Pond Evap Total " 1.64 1.42 3.59 5.02 4.87 7.45 7.67 6.54 5.06 3.79 2.56 2.08 51.69
Net Pond Evap Total " 1.52 1.13 1.57 4 2.3 6.54 7.47 3.85 3.57 3.33 2.32 1.93 39.53
Crook Avg. Temp F 29.97 19.51 40.01 45.89 56.96 71.52 75.09 71.96 64.94 50.4 40.94 31.2 49.87
Ref date as of 12/31/2021 Total Precip " 0.1 0.42 2.64 1.91 5.13 2.5 1.97 3.92 0.38 0.99 0.17 0.09 20.22
Site Type: Alfalfa Total Alfalfa ETr " 2.06 1.83 4.19 5.9 5.71 8.48 8.44 7.39 6.22 4.62 3.25 2.51 60.6
Total Growing Degee Days from March 1 0 0 128 212 310 585 694 640 498 301 179 86 3633
Gross Pond Evap Inch 1.73 1.54 3.52 4.96 4.8 7.12 7.09 6.21 5.22 3.88 2.73 2.11 50.91
Net Pond Evap Inch 1.66 1.24 1.67 3.62 1.21 5.37 5.71 3.46 4.96 3.19 2.61 2.05 36.75
 
Sterling Avg. Temp F 29.56 20.74 38.85 45.11 56.36 71.34 75.65 73.66 65.74 50.77 41.78 31.86 50.12
Ref date as of 12/31/2021 Total Precip " 0.15 0.33 2.35 2.83 4.46 2.58 0.71 0.68 0.39 0.45 0.1 0.09 15.12
Site Type: Alfalfa Total Alfalfa ETr " 1.87 1.94 3.96 5.46 5.5 8.75 8.17 8.15 6.32 4.44 2.98 2.26 59.8
Total Growing Degee Days from March 1 0 0 115 199 297 571 698 655 497 313 184 101 3630
Gross Pond Evap Inch 1.57 1.63 3.33 4.59 4.62 7.35 6.86 6.85 5.31 3.73 2.5 1.9 50.24
Net Pond Evap Inch 1.47 1.4 1.68 2.61 1.5 5.54 6.37 6.37 5.04 3.41 2.43 1.84 39.66
 
Brush Avg. Temp F 29.16 22.58 38.11 44.87 56.31 69.76 73.85 71.39 63.31 49.05 39.7 29.63 48.98
Ref date as of 12/31/2021 Total Precip " 0.28 0.47 2.27 2.63 3.33 0.6 2.51 0.75 0.49 0.34 0.09 0.13 13.89
Site Type: Alfalfa Total Alfalfa ETr " 1.83 1.92 3.96 5.53 5.65 8.09 8.28 7.25 5.89 4.56 2.75 2.31 58.02
Total Growing Degee Days from March 1 0 0 112 212 317 555 677 622 484 309 183 116 3587
Gross Pond Evap Inch 1.54 1.61 3.33 4.65 4.75 6.8 6.96 6.09 4.95 3.83 2.31 1.94 48.76
Net Pond Evap Inch 1.34 1.28 1.74 2.8 2.42 6.38 5.2 5.57 4.6 3.59 2.25 1.85 39.02
 
Fort Morgan Avg. Temp F 29.27 22.24 38.57 45.49 56.91 71.42 74.93 72.62 64.99 50.3 40.75 30.91 49.87
Ref date as of 12/31/2021 Total Precip " 0.17 0.35 1.86 2.25 3.33 1.29 3.81 0.65 0.32 0.38 0.08 0.03 14.52
Site Type: Turf Total Alfalfa ETr " 1.75 1.84 3.72 5.32 5.66 8.3 8.54 7.77 6.15 4.3 2.59 2.07 58.01
Total Growing Degee Days from March 1 0 0 112 205 320 572 698 637 498 309 171 83 3605
Gross Pond Evap Inch 1.47 1.55 3.12 4.47 4.75 6.97 7.17 6.53 5.17 3.61 2.18 1.74 48.73
Net Pond Evap Inch 1.35 1.3 1.82 2.89 2.42 6.07 4.51 6.07 4.94 3.35 2.12 1.72 38.56
 
Wiggins Avg. Temp F 28.85 22.05 37.68 44.73 55.72 71.31 73.75 71.15 63.81 49.04 39.28 29.57 48.91
Ref date as of 12/31/2021 Total Precip " 0.15 0.34 1.39 1.48 2.52 0.85 2.12 1.37 0.24 0.18 0.04 0.05 10.73
Site Type: Alfalfa Total Alfalfa ETr " 1.82 1.96 3.9 5.54 5.9 9.66 8.73 7.59 6.31 4.63 2.66 2.23 60.93
Total Growing Degee Days from March 1 0 0 108 197 299 568 678 608 488 317 167 83 3513
Gross Pond Evap Inch 1.53 1.65 3.28 4.65 4.96 8.11 7.33 6.38 5.3 3.89 2.23 1.87 51.18
Net Pond Evap Inch 1.42 1.41 2.3 3.62 3.19 7.52 5.85 5.42 5.13 3.76 2.21 1.84 43.67
 
Fort Collins East Avg. Temp F 29.21 23.2 37.05 44.62 54.78 70.12 72.07 69.18 62.59 49.94 42.27 33.34 49.03
Ref date as of 12/31/2021 Total Precip " 0.28 0.54 16.81 1.25 3.48 0.35 0.84 0.55 0.27 0.16 0.38 0.34 25.25
Site Type: Alfalfa Total Alfalfa ETr " 1.86 2.13 3.47 5.27 5.37 8.22 7.73 7.71 6.46 4.63 3.15 2.69 58.69
Total Growing Degee Days from March 1 0 0 80 191 286 539 631 566 470 274 158 75 3270
Gross Pond Evap Inch 1.56 1.79 2.91 4.43 4.51 6.9 6.49 6.48 5.43 3.89 2.65 2.26 49.3
Net Pond Evap Inch 1.37 1.41 0 3.55 2.07 6.66 5.91 6.09 5.24 3.78 2.38 2.02 40.48
 
Eaton Avg. Temp F 29.22 22.31 36.69 44.64 54.81 70.24 71.94 69.32 62.8 49.34 41.68 32.57 48.8
Ref date as of 12/31/2021 Total Precip " 0.21 0.41 1.35 1.83 2.37 1.54 0.6 0.36 0.36 0.25 0.38 0.42 10.08
Site Type: Alfalfa Total Alfalfa ETr " 1.86 2.04 3.55 5.44 5.74 8.73 7.39 7.06 6.28 4.43 2.83 2.55 57.9
Total Growing Degee Days from March 1 0 0 85 193 295 534 638 585 473 282 154 71 3310
Gross Pond Evap Inch 1.56 1.71 2.98 4.57 4.82 7.33 6.21 5.93 5.28 3.72 2.38 2.14 48.63
Net Pond Evap Inch 1.42 1.43 2.04 3.29 3.16 6.26 5.79 5.68 5.02 3.55 2.11 1.85 41.6
 
Johnsons Corner Avg. Temp F 30.98 24.12 38.46 46.08 54.6 70.51 74.42 72.66 66.66 51.99 44.82 36.95 51.02
Ref date as of 12/31/2021 Total Precip " 0.48 0.62 1.41 1.38 4.32 0.57 0.6 0.54 0.48 0.2 0.15 0.58 11.33
Site Type: Alfalfa Total Alfalfa ETr " 1.86 2.07 3.53 5.25 4.86 8.11 8.45 8.21 6.77 4.45 3.04 2.84 59.44
Total Growing Degee Days from March 1 0 0 77 178 262 563 702 651 500 263 161 81 3438
Gross Pond Evap Inch 1.56 1.74 2.97 4.41 4.08 6.81 7.1 6.9 5.69 3.74 2.55 2.39 49.94
Net Pond Evap Inch 1.23 1.3 1.98 3.44 1.06 6.41 6.68 6.52 5.35 3.6 2.45 1.98 42
 
Gilcrest Avg. Temp F 27.39 22.9 36.66 44.91 54.7 70.57 73.38 70.68 62.96 49.12 40.59 32.75 48.88
Ref date as of 12/31/2021 Total Precip " 0.34 0.4 1.51 1.02 3.29 0.94 1.38 0.68 1.42 0.67 0.13 0.33 12.11
Site Type: Alfalfa Total Alfalfa ETr " 1.62 1.92 3.52 5.28 5.26 8.96 8.52 7.86 5.94 4.36 2.68 2.6 58.52
Total Growing Degee Days from March 1 0 0 84 198 281 554 666 599 469 273 162 83 3369
Gross Pond Evap Inch 1.36 1.61 2.96 4.44 4.42 7.53 7.16 6.6 4.99 3.66 2.25 2.18 49.16
Net Pond Evap Inch 1.12 1.33 1.9 3.72 2.12 6.87 6.19 6.13 4 3.19 2.16 1.95 40.68
 
Longmont South Avg. Temp F 30.59 24.39 38.1 45.07 53.82 69.26 73.45 71.85 64.8 50.67 45.53 37.47 50.42
Ref date as of 12/31/2021 Total Precip " 0.44 0.66 1.63 1.95 4.51 0.71 0.94 1.05 0.31 0.16 0.2 0.45 13.01
Site Type: Alfalfa Total Alfalfa ETr " 2.04 2.29 3.48 5.03 4.98 8.22 8.16 6.72 6.03 4.16 3.38 3.02 57.51
Total Growing Degee Days from March 1 0 0 80 179 253 520 658 616 478 268 184 102 3338
Gross Pond Evap Inch 1.71 1.92 2.92 4.23 4.18 6.9 6.85 5.64 5.07 3.49 2.84 2.54 48.29
Net Pond Evap Inch 1.41 1.46 1.78 2.86 1.03 6.41 6.2 4.91 4.85 3.38 2.7 2.22 39.21
 
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 29.74 24.12 37.71 45.2 54.79 69.93 73.22 70.19 63.2 48.76 42.25 33.71 49.4
Ref date as of 12/31/2021 Total Precip " 0.27 0.5 1.39 1.85 4.91 0.44 0.68 0.66 0.61 0.24 0.14 0.06 11.75
Site Type: Turf Total Alfalfa ETr " 1.81 2.07 3.37 4.88 5.15 7.47 7.21 6.83 5.65 3.58 2.57 2.2 52.79
Total Growing Degee Days from March 1 0 0 85 179 282 528 644 576 471 254 153 68 3240
Gross Pond Evap Inch 1.52 1.74 2.83 4.1 4.33 6.27 6.06 5.74 4.75 3.01 2.16 1.85 44.36
Net Pond Evap Inch 1.33 1.39 1.86 2.8 0.89 5.97 5.58 5.28 4.32 2.84 2.06 1.81 36.13
 
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 30.78 24.87 39.41 46.83 56.82 72.84 75.98 73.27 65.78 51.15 42.76 34.23 51.23
Ref date as of 12/31/2021 Total Precip " 0.53 0.51 1.38 1.56 3.64 0.81 1.98 0.41 8.21 0.21 0.12 0.43 19.79
Site Type: Turf Total Alfalfa ETr " 1.76 1.87 3.45 5.13 5.43 8.09 7.76 7.06 5.71 3.79 2.42 2.06 54.53
Total Growing Degee Days from March 1 0 0 102 203 316 593 721 659 501 270 155 71 3591
Gross Pond Evap Inch 1.48 1.57 2.9 4.31 4.56 6.8 6.52 5.93 4.8 3.18 2.03 1.73 45.81
Net Pond Evap Inch 1.11 1.21 1.93 3.22 2.01 6.23 5.13 5.64 0 3.04 1.95 1.43 32.9
 
Loveland Avg. Temp F 29.89 24.18 38.39 45.73 55.5 70.65 74.49 72.09 65.63 51.19 44.4 36.23 50.7
Ref date as of 12/31/2021 Total Precip " 0.34 0.87 1.95 1.94 4.29 1.07 0.74 0.66 0.42 0.15 0.13 0.66 13.22
Site Type: Turf Total Alfalfa ETr " 1.69 1.86 3.3 4.79 5.03 7.26 7.19 6.61 5.36 3.71 2.89 2.42 52.11
Total Growing Degee Days from March 1 0 0 104 207 313 575 698 640 516 307 197 93 3650
Gross Pond Evap Inch 1.42 1.56 2.77 4.02 4.23 6.1 6.04 5.55 4.5 3.12 2.43 2.03 43.77
Net Pond Evap Inch 1.18 0.95 1.41 2.67 1.22 5.35 5.52 5.09 4.21 3.01 2.34 1.57 34.52
 
Berthoud Avg. Temp F 30.78 24.09 38.25 45.82 54.84 71 74.71 72.78 66.53 51.71 44.63 37.46 51.05
Ref date as of 12/31/2021 Total Precip " 0.39 0.51 1.82 1.59 4.07 0.53 1 0.58 0.15 0.06 0.05 0.45 11.2
Site Type: Turf Total Alfalfa ETr " 1.86 2.08 3.43 5.03 5.06 8.1 8.13 7.76 6.17 3.95 2.7 2.52 56.79
Total Growing Degee Days from March 1 0 0 80 185 277 579 712 664 505 268 159 95 3524
Gross Pond Evap Inch 1.56 1.75 2.88 4.23 4.25 6.8 6.83 6.52 5.18 3.32 2.27 2.12 47.71
Net Pond Evap Inch 1.29 1.39 1.61 3.11 1.4 6.43 6.13 6.11 5.08 3.28 2.23 1.8 39.86
 
Longmont West Avg. Temp F 30.83 24.56 38.39 45.56 54.95 70.77 74.37 72.14 65.19 50.85 45.6 37.63 50.9
Ref date as of 12/31/2021 Total Precip " 0.26 0.4 1.3 0.1 1.42 0.98 2.86 1.67 0.63 0.48 0.15 0 10.25
Site Type: Turf Total Alfalfa ETr " 1.82 1.95 3.29 4.62 4.87 7.62 7.31 6.89 5.25 3.66 2.77 2.47 52.52
Total Growing Degee Days from March 1 0 0 0 0 239 555 693 631 484 287 184 96 3169
Gross Pond Evap Inch 1.53 1.64 2.76 3.88 4.09 6.4 6.14 5.79 4.41 3.07 2.33 2.07 44.11
Net Pond Evap Inch 1.35 1.36 1.85 3.81 3.1 5.71 4.14 4.62 3.97 2.74 2.22 2.07 36.94
 
Fort Lupton Avg. Temp F 30.76 24.61 38.59 46.03 56.14 71.71 75.7 73.95 66.88 52.36 45.58 37.1 51.62
Ref date as of 12/31/2021 Total Precip " 0.33 0.67 1.49 1.48 3.21 0.43 0.37 1.26 0.32 0.32 0.19 0.37 10.44
Site Type: Turf Total Alfalfa ETr " 1.99 2.23 3.77 5.32 5.03 9.03 9.2 8.53 7.06 4.88 3.45 2.9 63.39
Total Growing Degee Days from March 1 0 0 83 186 259 582 717 678 516 288 184 99 3592
Gross Pond Evap Inch 1.67 1.87 3.17 4.47 4.23 7.59 7.73 7.17 5.93 4.1 2.9 2.44 53.27
Net Pond Evap Inch 1.44 1.4 2.12 3.43 1.98 7.28 7.47 6.28 5.71 3.88 2.77 2.18 45.94
 
Boulder NW Avg. Temp F 32.92 26.06 39.23 45.76 54.83 70.36 73.91 72.23 66.46 51.53 46.59 39.19 51.59
Ref date as of 12/31/2021 Total Precip " 0.28 0.69 1.83 2.77 4.93 2.59 1.78 1.77 0.34 0.32 0.18 0.15 17.63
Site Type: Turf Total Alfalfa ETr " 1.61 1.86 1.56 2.51 4.51 7.2 6.94 7.02 5.75 3.83 3.34 2.92 49.05
Total Growing Degee Days from March 1 0 0 93 180 273 542 670 637 500 245 165 93 3398
Gross Pond Evap Inch 1.35 1.56 1.31 2.11 3.79 6.05 5.83 5.9 4.83 3.22 2.81 2.45 41.21
Net Pond Evap Inch 1.16 1.08 0.03 0.17 0.34 4.24 4.58 4.66 4.59 2.99 2.68 2.35 28.87
 
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 34.28 26.65 39.75 45.94 54.66 70.05 73.31 72.4 66.63 53.29 49.04 41.75 52.31
Ref date as of 12/31/2021 Total Precip " 0.27 0.63 1.62 2.72 6.54 2.35 2.62 1.11 0.67 0.19 0.05 0.16 18.93
Site Type: Turf Total Alfalfa ETr " 2.29 2.44 3.47 4.84 5.07 7.71 7.58 7.48 5.96 4.28 3.95 3.51 58.58
Total Growing Degee Days from March 1 0 0 74 163 247 523 653 621 469 252 175 96 3273
Gross Pond Evap Inch 1.92 2.05 2.91 4.07 4.26 6.48 6.37 6.28 5.01 3.6 3.32 2.95 49.22
Net Pond Evap Inch 1.73 1.61 1.78 2.16 0 4.83 4.53 5.51 4.54 3.46 3.28 2.84 36.27
Greeley04 Avg. Temp F 29.29 22.65 37.76 52.8 60.1 71.67 74.04 70.42 63.98 50.24 41.02 31.87 50.49
Ref date as of 12/31/2021 Total Precip " 0.09 0.12 0.68 0.96 2.34 0.23 3.15 0.31 0.54 0.15 0.12 0.02 8.71
Site Type: Fully irrigated Total Alfalfa ETr " 2.27 2.48 3.9 1.31 2.33 10.64 8.58 7.9 6.74 5.28 3.28 3.28 57.99
Total Growing Degee Days from March 1 0 0 94 72 89 575 689 596 482 287 164 80 3128
Gross Pond Evap Inch 1.91 2.08 3.28 1.1 1.96 8.94 7.21 6.64 5.66 4.44 2.76 2.76 48.74
Net Pond Evap Inch 1.84 2 2.8 0.43 0.32 8.78 5 6.42 5.28 4.33 2.67 2.74 42.61