Pond Evaporation Calculation 1/31/23
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 2022 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 25.22 25.51 36.55 47.06 57.95 72.71 77.72 76.53 66.9 49.23 31.34 22.28 49.08
Ref date as of 12/31/2022 Total Precip " 0.33 0.23 1.01 0.58 1.71 0.77 1.65 0.04 1.72 0.16 0.23 1 9.43
Site Type: Alfalfa Total Alfalfa ETr " 1.98 2.76 4.4 7.74 8.15 11.11 10.41 9.76 7.44 5.13 2.63 1.15 72.66
Total Growing Degee Days from March 1 0 0 138 206 355 597 738 712 501 310 83 8 3648
Gross Pond Evap Total " 1.66 2.32 3.7 6.5 6.85 9.33 8.74 8.2 6.25 4.31 2.21 0.97 61.04
Net Pond Evap Total " 1.43 2.16 2.99 6.1 5.65 8.79 7.59 8.17 5.05 4.2 2.05 0.27 54.45
Crook Avg. Temp F 24.59 25.21 37.09 46.88 56.98 71.66 76.79 75.07 65.68 48 31.11 22.55 48.47
Ref date as of 12/31/2022 Total Precip " 0.32 0.23 0.88 0.52 1.9 0.42 2.58 1.65 1.46 0.49 0.2 0.48 11.13
Site Type: Alfalfa Total Alfalfa ETr " 1.76 2.52 4.39 7.67 7.58 10.32 9.33 8.38 6.52 4.68 2.5 1.18 66.83
Total Growing Degee Days from March 1 0 0 147 206 348 568 712 687 482 299 78 8 3535
Gross Pond Evap Inch 1.48 2.12 3.69 6.44 6.37 8.67 7.84 7.04 5.48 3.93 2.1 0.99 56.15
Net Pond Evap Inch 1.25 1.96 3.07 6.08 5.04 8.37 6.03 5.88 4.45 3.59 1.96 0.66 48.34
 
Sterling Avg. Temp F 24.74 26.41 38.49 48.53 57.79 71.51 76.91 75.23 66.52 48.51 31.22 22.11 49
Ref date as of 12/31/2022 Total Precip " 0.36 0.31 1.05 0.23 2.37 0.73 0.99 1.56 1.22 0.46 0.24 0.71 10.23
Site Type: Alfalfa Total Alfalfa ETr " 1.57 2.3 4.09 7.55 7.42 9.7 9.3 8.4 6.42 4.36 2.4 1.28 64.79
Total Growing Degee Days from March 1 0 0 155 214 350 571 733 700 500 283 71 18 3595
Gross Pond Evap Inch 1.32 1.93 3.44 6.34 6.23 8.15 7.81 7.06 5.39 3.66 2.02 1.08 54.43
Net Pond Evap Inch 1.07 1.72 2.7 6.18 4.57 7.64 7.12 5.96 4.54 3.34 1.85 0.58 47.27
 
Brush Avg. Temp F 21.66 24.38 38.11 48.58 57.23 71.6 76.87 74.75 64.44 48.19 30.82 22.57 48.27
Ref date as of 12/31/2022 Total Precip " 0.62 0.42 1.2 0.12 1.88 0.94 4.11 0.3 0.75 0.34 0.29 1.01 11.98
Site Type: Alfalfa Total Alfalfa ETr " 1.52 2.01 4.27 7.79 6.95 8.75 8.49 7.91 5.38 4.24 2.44 1.54 61.29
Total Growing Degee Days from March 1 0 0 181 249 374 567 723 682 477 307 82 35 3677
Gross Pond Evap Inch 1.28 1.69 3.59 6.54 5.84 7.35 7.13 6.64 4.52 3.56 2.05 1.29 51.48
Net Pond Evap Inch 0.84 1.39 2.75 6.46 4.52 6.69 4.25 6.43 3.99 3.32 1.85 0.59 43.08
 
Fort Morgan Avg. Temp F 22.78 24.93 38.07 48.37 57.2 70.47 75.81 74.46 65.55 48.94 31.34 23.34 48.44
Ref date as of 12/31/2022 Total Precip " 0.43 0.4 1.37 0.13 2.27 1.7 4.02 0.35 1.16 0.02 0.15 0.5 12.5
Site Type: Turf Total Alfalfa ETr " 1.43 2 3.96 7.24 7.44 8.58 8.75 8.12 5.64 3.87 2.22 1.49 60.74
Total Growing Degee Days from March 1 0 0 156 221 354 556 720 693 487 284 70 23 3564
Gross Pond Evap Inch 1.2 1.68 3.33 6.08 6.25 7.21 7.35 6.82 4.74 3.25 1.86 1.25 51.02
Net Pond Evap Inch 0.9 1.4 2.37 5.99 4.66 6.02 4.54 6.58 3.93 3.24 1.76 0.9 42.29
 
Wiggins Avg. Temp F 20.66 23.66 36.74 47.1 56.08 69.84 74.85 73.22 64.58 47.5 29.84 21.7 47.15
Ref date as of 12/31/2022 Total Precip " 0.29 0.08 1 0.22 1.44 0.84 1.93 0.17 1.59 0.47 0.11 0.3 8.44
Site Type: Alfalfa Total Alfalfa ETr " 1.27 1.95 4.13 7.91 7.62 9.64 9.26 8.49 6.05 4.07 2.23 1.47 64.09
Total Growing Degee Days from March 1 0 0 155 216 345 538 678 654 471 275 65 24 3421
Gross Pond Evap Inch 1.07 1.64 3.47 6.64 6.4 8.1 7.78 7.13 5.08 3.42 1.87 1.23 53.83
Net Pond Evap Inch 0.86 1.58 2.77 6.49 5.39 7.51 6.43 7.01 3.97 3.09 1.8 1.02 47.92
 
Fort Collins East Avg. Temp F 24.32 25.19 38.19 47.53 55.97 68.4 73.24 71.16 62.93 49.37 30.62 26.47 47.78
Ref date as of 12/31/2022 Total Precip " 0.64 0.59 0.71 0.13 1.85 0.42 3.43 0.31 0.95 0.13 0.57 0.33 10.06
Site Type: Alfalfa Total Alfalfa ETr " 1.53 2.14 4.41 7.74 7.54 9.3 8.39 7.57 5.52 4.59 2.31 1.94 62.98
Total Growing Degee Days from March 1 0 0 141 219 337 519 651 624 450 284 55 15 3295
Gross Pond Evap Inch 1.29 1.8 3.7 6.5 6.33 7.81 7.05 6.36 4.64 3.86 1.94 1.63 52.91
Net Pond Evap Inch 0.84 1.38 3.21 6.41 5.04 7.52 4.65 6.14 3.97 3.76 1.54 1.4 45.86
 
Eaton Avg. Temp F 23.68 24.84 38.05 47.57 56.1 68.53 73.31 70.52 62.42 47.97 29.43 24.42 47.24
Ref date as of 12/31/2022 Total Precip " 0.67 0.58 0.8 0.07 1.99 0.26 1.76 0.85 0.99 0.17 0.67 0.44 9.25
Site Type: Alfalfa Total Alfalfa ETr " 1.32 1.89 4.29 8.13 7.61 9.05 8.19 7.32 5.31 4.21 2.14 1.65 61.11
Total Growing Degee Days from March 1 0 0 138 221 340 525 665 620 443 267 50 4 3273
Gross Pond Evap Inch 1.11 1.59 3.6 6.83 6.39 7.6 6.88 6.15 4.46 3.54 1.8 1.39 51.34
Net Pond Evap Inch 0.64 1.18 3.04 6.78 5 7.42 5.65 5.55 3.77 3.42 1.33 1.08 44.86
 
Johnsons Corner Avg. Temp F 26.45 25.88 39.39 48.85 56.38 69.31 75.01 73.39 66.13 52.37 33.15 27.5 49.48
Ref date as of 12/31/2022 Total Precip " 0.83 1.01 0.92 0.14 2.97 0.3 1.57 0.97 1.07 0.19 0.76 0.83 11.56
Site Type: Alfalfa Total Alfalfa ETr " 1.35 1.86 3.91 7.21 6.83 8.57 8.48 7.87 5.81 4.37 2.18 1.71 60.15
Total Growing Degee Days from March 1 0 0 129 210 322 544 710 698 478 276 51 18 3436
Gross Pond Evap Inch 1.13 1.56 3.28 6.06 5.74 7.2 7.12 6.61 4.88 3.67 1.83 1.44 50.52
Net Pond Evap Inch 0.55 0.86 2.64 5.96 3.66 6.99 6.02 5.93 4.13 3.54 1.3 0.86 42.44
 
Gilcrest Avg. Temp F 20.42 22.31 38.23 48.84 56.36 69.24 74.43 72.89 64.62 49.91 31.05 23.91 47.68
Ref date as of 12/31/2022 Total Precip " 0.79 0.67 1.06 0.24 3.2 1.07 2.02 0.84 0.95 0.52 0.49 0.54 12.39
Site Type: Alfalfa Total Alfalfa ETr " 1.18 1.69 3.93 7.78 7.43 8.79 8.73 8.15 5.6 4.1 2.12 1.6 61.1
Total Growing Degee Days from March 1 0 0 141 230 344 538 690 668 469 286 57 12 3435
Gross Pond Evap Inch 0.99 1.42 3.3 6.54 6.24 7.38 7.33 6.85 4.7 3.44 1.78 1.34 51.31
Net Pond Evap Inch 0.44 0.95 2.56 6.37 4 6.63 5.92 6.26 4.04 3.08 1.44 0.97 42.66
 
Longmont South Avg. Temp F 27.32 27.36 39.78 49.16 56.74 68.95 74.56 71.77 64.33 51 32 28.14 49.26
Ref date as of 12/31/2022 Total Precip " 0.59 0.85 0.76 0.16 2.79 0.39 1.42 1.48 0.89 0.54 0.77 1.2 11.84
Site Type: Alfalfa Total Alfalfa ETr " 1.54 2.14 4.05 7.36 7.13 8.1 8.29 7.23 5.34 4.09 2.01 1.95 59.23
Total Growing Degee Days from March 1 0 0 148 222 326 525 682 648 449 263 50 29 3342
Gross Pond Evap Inch 1.29 1.8 3.4 6.18 5.99 6.8 6.96 6.07 4.49 3.44 1.69 1.64 49.75
Net Pond Evap Inch 0.88 1.2 2.87 6.07 4.04 6.53 5.97 5.04 3.86 3.06 1.15 0.8 41.47
 
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 26.07 25.89 38.4 47.57 55.44 67.51 72.98 71.29 62.75 48.52 31.4 27.41 47.94
Ref date as of 12/31/2022 Total Precip " 0.65 0.57 0.67 0.16 2.67 0.8 3.33 0.45 1.33 0.08 0 0 10.71
Site Type: Turf Total Alfalfa ETr " 1.51 2.05 3.76 6.36 6.11 7.63 6.81 6.48 4.62 3.56 2 1.69 52.58
Total Growing Degee Days from March 1 0 0 130 200 319 496 641 621 437 267 58 20 3189
Gross Pond Evap Inch 1.27 1.72 3.16 5.34 5.13 6.41 5.72 5.44 3.88 2.99 1.68 1.42 44.16
Net Pond Evap Inch 0.81 1.32 2.69 5.23 3.26 5.85 3.39 5.13 2.95 2.93 1.68 1.42 36.66
 
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 24.39 25.32 38.95 49.01 56.95 69.97 75.81 74.01 65.86 50.83 31.97 25.55 49.05
Ref date as of 12/31/2022 Total Precip " 0.8 0.91 1.08 0.12 2.42 0.23 2.24 0.39 0.95 0.28 0.61 0.53 10.56
Site Type: Turf Total Alfalfa ETr " 1.18 1.73 3.75 7.04 6.58 7.84 7.73 7.08 4.97 3.59 1.95 1.45 54.89
Total Growing Degee Days from March 1 0 0 135 221 342 556 718 696 480 272 50 15 3485
Gross Pond Evap Inch 0.99 1.45 3.15 5.91 5.53 6.59 6.49 5.95 4.17 3.02 1.64 1.22 46.11
Net Pond Evap Inch 0.43 0.82 2.39 5.83 3.83 6.42 4.93 5.67 3.51 2.82 1.21 0.85 38.71
 
Loveland Avg. Temp F 26.37 25.56 39.26 48.98 56.75 69.23 75.17 72.49 64.44 50.39 31.66 27.13 48.95
Ref date as of 12/31/2022 Total Precip " 1 1.22 0.82 0.18 3.17 0.58 1.85 1.34 1.23 0.34 0.78 0.97 13.48
Site Type: Turf Total Alfalfa ETr " 1.51 1.99 3.95 6.78 6.57 7.89 7.79 7.13 4.97 3.77 1.87 1.6 55.82
Total Growing Degee Days from March 1 0 0 154 228 352 556 713 682 487 309 67 21 3569
Gross Pond Evap Inch 1.27 1.67 3.32 5.7 5.52 6.63 6.54 5.99 4.17 3.17 1.57 1.34 46.89
Net Pond Evap Inch 0.57 0.82 2.74 5.57 3.3 6.22 5.25 5.05 3.31 2.93 1.02 0.67 37.45
 
Berthoud Avg. Temp F 27.21 26.51 39.99 49.46 57.25 70.23 75.82 74.19 66.99 52.88 33.81 28.3 50.22
Ref date as of 12/31/2022 Total Precip " 0.7 0.83 0.91 0.08 2.78 0.24 2.24 1.52 0.87 0.31 0.65 1.05 12.18
Site Type: Turf Total Alfalfa ETr " 1.28 1.85 3.89 6.91 6.87 8.23 8.2 7.4 5.33 3.91 2.03 1.64 57.54
Total Growing Degee Days from March 1 0 0 129 206 333 573 736 722 502 267 49 16 3533
Gross Pond Evap Inch 1.08 1.55 3.27 5.8 5.77 6.91 6.89 6.22 4.48 3.28 1.71 1.38 48.34
Net Pond Evap Inch 0.59 0.97 2.63 5.75 3.82 6.75 5.32 5.15 3.87 3.07 1.25 0.64 39.81
 
Longmont West Avg. Temp F 27.58 27.11 40.01 49.84 57.23 69.88 75.76 73.87 66.07 51.29 33.11 29.22 50.08
Ref date as of 12/31/2022 Total Precip " 0.04 0.01 0.03 0.1 3.39 0.19 0.06 2.01 1.19 0.41 0 0 7.43
Site Type: Turf Total Alfalfa ETr " 1.55 1.99 3.81 6.52 6.39 7.39 7.34 6.68 4.78 3.4 1.81 1.67 53.33
Total Growing Degee Days from March 1 0 0 133 215 331 564 722 697 478 259 57 39 3495
Gross Pond Evap Inch 1.3 1.67 3.2 5.48 5.37 6.21 6.17 5.61 4.02 2.86 1.52 1.4 44.81
Net Pond Evap Inch 1.27 1.66 3.18 5.41 2.99 6.07 6.12 4.2 3.18 2.57 1.52 1.4 39.57
 
Fort Lupton Avg. Temp F 27.61 27.56 39.94 49.36 57.44 69.99 76.03 74.36 66.57 51.74 32.9 27.78 50.11
Ref date as of 12/31/2022 Total Precip " 1.03 1 1.09 0.17 2.69 2.55 0.71 0.92 0.9 0.61 0.47 0.91 13.05
Site Type: Turf Total Alfalfa ETr " 1.61 2.15 4.34 7.41 8.01 9.01 9.25 8.35 6.38 4.38 2.23 2.02 65.14
Total Growing Degee Days from March 1 0 0 147 215 338 566 728 712 494 266 53 24 3543
Gross Pond Evap Inch 1.35 1.81 3.65 6.22 6.73 7.57 7.77 7.01 5.36 3.68 1.87 1.7 54.72
Net Pond Evap Inch 0.63 1.11 2.88 6.11 4.85 5.78 7.27 6.37 4.73 3.25 1.54 1.06 45.58
 
Boulder NW Avg. Temp F 31.28 28.48 39.71 48.51 55.95 68.86 74.87 72.56 65.31 51.3 33.32 31.88 50.17
Ref date as of 12/31/2022 Total Precip " 1.04 1.17 1.01 0.14 3.97 0.15 1.29 2.19 1.49 0.27 0 0 12.72
Site Type: Turf Total Alfalfa ETr " 2.12 3.14 5.13 8.55 7.11 6.98 7.28 7.01 4.89 3.82 1.97 2.16 60.16
Total Growing Degee Days from March 1 0 0 135 202 309 530 687 655 467 244 44 33 3306
Gross Pond Evap Inch 1.78 2.64 4.31 7.18 5.97 5.86 6.12 5.89 4.11 3.21 1.65 1.81 50.53
Net Pond Evap Inch 1.05 1.82 3.6 7.08 3.19 5.76 5.21 4.36 3.06 3.02 1.65 1.81 41.61
 
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 34.54 30.7 41.24 49.38 56.56 69.42 74.98 73.19 67.02 53.35 35.31 34.11 51.65
Ref date as of 12/31/2022 Total Precip " 0.01 0.01 0.04 0.12 3.3 0.27 2.82 2.87 1.23 0.22 0 0 10.89
Site Type: Turf Total Alfalfa ETr " 2.4 2.66 4.16 6.62 6.65 7.8 7.9 7.04 5.3 4.28 2.21 2.7 59.72
Total Growing Degee Days from March 1 0 0 128 192 305 513 671 679 473 244 42 40 3287
Gross Pond Evap Inch 2.02 2.23 3.49 5.56 5.59 6.55 6.64 5.91 4.45 3.6 1.86 2.27 50.17
Net Pond Evap Inch 2.01 2.23 3.47 5.48 3.28 6.36 4.66 3.9 3.59 3.44 1.86 2.27 42.55
Greeley04 Avg. Temp F 20.74 23.7 38.1 48.17 56.46 68.9 73.83 71.64 63.93 49.23 30.86 23.6 47.43
Ref date as of 12/31/2022 Total Precip " 0.33 0.19 0.61 0.2 2.02 0.42 1.18 0.63 1.1 0.27 0.14 0.12 7.21
Site Type: Fully irrigated Total Alfalfa ETr " 1.31 1.89 4.84 9.03 8.27 9.96 9.47 8.24 6.34 4.54 2.69 2.17 68.75
Total Growing Degee Days from March 1 0 0 142 228 346 541 680 654 465 286 56 15 3413
Gross Pond Evap Inch 1.1 1.59 4.07 7.59 6.95 8.37 7.95 6.92 5.33 3.81 2.26 1.82 57.76
Net Pond Evap Inch 0.87 1.45 3.64 7.45 5.53 8.07 7.13 6.48 4.56 3.62 2.16 1.74 52.7