Pond Evaporation Calculation 1/28/09
Weather Station Data provided by Northern Colorado Water Conservancy District
See Weather Station Location Map at:
http://www.ncwcd.org/ims/ims_weather_form.asp
Notes:
Current month reflects values through "Reference Date".
Pond Evap. calculated per recent Division 1 Water Court decree language:
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 2002 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 28.15 31.23 30.87 50.03 57.27 74.7 77.3 70.75 62.86 42.67 36.49 29.71 49.34
Ref date as of 12/31/2002 Total Precip " 0.08 0.06 0.12 0.5 0.41 2.97 1.06 1.55 0.93 1.65 0.17 0.07 9.57
Site Type: Alfalfa Total Alfalfa ETr " 3.17 4.53 3.95 7.56 9.54 12.64 11.03 8.48 7.14 3.97 3.29 2.94 78.24
Total Growing Degee Days from March 1 0 0 72 246 346 634 720 629 447 178 82 44 3398
Gross Pond Evap Total " 2.66 3.81 3.32 6.35 8.01 10.62 9.27 7.12 6 3.33 2.76 2.47 65.72
Net Pond Evap Total " 2.61 3.76 3.23 6 7.73 8.54 8.52 6.04 5.35 2.18 2.64 2.42 59.02
Crook Avg. Temp F 26.81 29.67 30.78 49.72 55.57 72.6 76.51 70.33 61.59 41.94 36.3 29.41 48.44
Ref date as of 12/31/2002 Total Precip " 0.02 0.14 0.32 0.34 0.79 2 0.89 3.87 0.58 2.5 0.27 0.01 11.73
Site Type: Alfalfa Total Alfalfa ETr " 3.25 4.11 3.96 7.15 7.45 10.74 10.6 8.85 6.47 3.98 3.35 3.01 72.92
Total Growing Degee Days from March 1 0 0 86 256 319 567 680 615 427 175 82 43 3250
Gross Pond Evap Inch 2.73 3.45 3.33 6.01 6.26 9.02 8.9 7.43 5.43 3.34 2.81 2.53 61.24
Net Pond Evap Inch 2.72 3.35 3.1 5.77 5.71 7.62 8.28 4.73 5.03 1.59 2.63 2.52 53.05
 
Sterling Avg. Temp F 26.52 29.23 31.32 50.07 56.14 72.6 76.65 70.24 61.67 42 35.55 29.25 48.44
Ref date as of 12/31/2002 Total Precip " 0 0.04 0.17 0.16 0.66 0.52 1.08 2.03 0.74 0.92 0.37 0 6.69
Site Type: Alfalfa Total Alfalfa ETr " 3 3.78 4.09 7.36 7.43 10.58 10.79 8.99 6.41 3.66 2.92 2.77 71.78
Total Growing Degee Days from March 1 0 0 95 266 330 568 698 612 423 174 82 47 3295
Gross Pond Evap Inch 2.52 3.18 3.44 6.18 6.24 8.89 9.06 7.55 5.38 3.07 2.45 2.33 60.29
Net Pond Evap Inch 2.52 3.15 3.32 6.07 5.78 8.52 8.31 6.13 4.87 2.43 2.19 2.33 55.62
 
Brush Avg. Temp F 26.91 29.85 32.21 50.67 56.6 72.32 77.03 70.66 62.85 43.04 35.41 29.68 48.94
Ref date as of 12/31/2002 Total Precip " 0.22 0 0.03 0.44 0.52 1.22 0.03 0.12 0.11 0.79 0.18 0.08 3.74
Site Type: Alfalfa Total Alfalfa ETr " 2.87 3.86 4.33 7.46 7.66 10.67 11.4 9.75 7.23 4.15 2.83 2.6 74.81
Total Growing Degee Days from March 1 0 0 100 275 339 573 690 621 435 192 71 42 3338
Gross Pond Evap Inch 2.41 3.24 3.64 6.27 6.43 8.96 9.58 8.19 6.07 3.49 2.38 2.18 62.84
Net Pond Evap Inch 2.26 3.24 3.62 5.96 6.07 8.11 9.56 8.11 6 2.93 2.25 2.13 60.24
 
Fort Morgan Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A 79.3 71.09 62.96 43.63 35.52 29.86 53.73
Ref date as of 12/31/2002 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A 0 1.43 0.66 0.96 0.27 0.1 3.42
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A 1.07 9.41 6.51 3.98 2.87 2.31 26.15
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A 64 644 447 200 79 41 1475
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A 0.9 7.9 5.47 3.34 2.41 1.94 21.96
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A 0.9 6.9 5.01 2.67 2.22 1.87 19.57
 
Wiggins Avg. Temp F 25.33 29.23 31.63 50.26 56.68 71.7 74.52 68.72 61.2 42.14 34.73 28.91 47.92
Ref date as of 12/31/2002 Total Precip " 0.28 0 0.1 0.4 0.44 1.05 0.03 0.66 0.7 0.97 0.22 0.11 4.96
Site Type: Alfalfa Total Alfalfa ETr " 2.44 3.71 4.16 7.63 7.99 10.38 9.96 8.49 6.14 3.67 2.54 2.28 69.39
Total Growing Degee Days from March 1 0 0 103 273 336 567 673 599 410 178 72 38 3249
Gross Pond Evap Inch 2.05 3.12 3.49 6.41 6.71 8.72 8.37 7.13 5.16 3.08 2.13 1.92 58.29
Net Pond Evap Inch 1.85 3.12 3.42 6.13 6.4 7.98 8.35 6.67 4.67 2.4 1.98 1.84 54.81
 
Fort Collins East Avg. Temp F 25.61 29.1 31.2 48.41 53.38 68.26 72.26 65.36 58.5 40.23 33.58 29.46 46.28
Ref date as of 12/31/2002 Total Precip " 0.33 0.03 0.26 0.1 1.11 0.94 0.73 1.13 0.94 0.44 0.37 0.02 6.4
Site Type: Alfalfa Total Alfalfa ETr " 2.22 3.31 3.6 6.17 5.35 8.76 9.35 7.47 5.48 3.74 2.75 2.53 60.73
Total Growing Degee Days from March 1 0 0 75 230 277 513 608 509 363 148 60 30 2813
Gross Pond Evap Inch 1.86 2.78 3.02 5.18 4.49 7.36 7.85 6.27 4.6 3.14 2.31 2.13 50.99
Net Pond Evap Inch 1.63 2.76 2.84 5.11 3.72 6.7 7.34 5.48 3.95 2.83 2.05 2.11 46.52
 
Eaton Avg. Temp F 25.57 29.55 31.69 49.13 54.85 69.78 72.88 66.29 60.08 40.98 33.88 29.88 47.05
Ref date as of 12/31/2002 Total Precip " 0.21 0 0.2 0.12 1.39 1.27 1.13 0.41 0.6 0.73 0.37 0.02 6.45
Site Type: Alfalfa Total Alfalfa ETr " 2.33 3.86 4.25 7.48 7.05 9.28 8.27 6.45 6 3.73 2.67 2.51 63.88
Total Growing Degee Days from March 1 0 0 97 246 305 547 649 539 383 155 64 35 3020
Gross Pond Evap Inch 1.96 3.24 3.57 6.28 5.92 7.8 6.95 5.42 5.04 3.13 2.24 2.11 53.66
Net Pond Evap Inch 1.81 3.24 3.43 6.2 4.95 6.91 6.16 5.13 4.62 2.62 1.98 2.09 49.14
 
Johnsons Corner Avg. Temp F 26.72 31.28 32.66 50.11 55.08 70.51 74.94 67.99 61.48 42.4 34.58 31.11 48.24
Ref date as of 12/31/2002 Total Precip " 0.61 0 0.25 0.29 2.54 0.54 0.26 0.41 1.44 0.87 0.53 0 7.74
Site Type: Alfalfa Total Alfalfa ETr " 1.98 3.17 3.62 6.76 6.6 9.55 9.46 7.46 5.67 3.39 2.19 2.03 61.88
Total Growing Degee Days from March 1 0 0 77 245 302 547 683 565 400 164 64 37 3084
Gross Pond Evap Inch 1.66 2.66 3.04 5.68 5.54 8.02 7.95 6.27 4.76 2.85 1.84 1.71 51.98
Net Pond Evap Inch 1.24 2.66 2.87 5.48 3.77 7.64 7.76 5.98 3.75 2.24 1.47 1.71 46.57
 
Gilcrest Avg. Temp F 24.9 30.24 32.17 50.35 55.24 69.8 72.72 66.89 60.04 41.79 33.77 29.69 47.3
Ref date as of 12/31/2002 Total Precip " 0.5 0.02 0.22 0.14 1.86 0.7 0.8 0.52 0.69 0.37 0.58 0 6.4
Site Type: Alfalfa Total Alfalfa ETr " 1.78 3.17 3.69 7 6.34 8.55 7.97 6.81 5.02 3.21 2.08 2.14 57.76
Total Growing Degee Days from March 1 0 0 83 262 309 540 644 562 406 172 73 41 3092
Gross Pond Evap Inch 1.5 2.66 3.1 5.88 5.33 7.18 6.69 5.72 4.22 2.7 1.75 1.8 48.53
Net Pond Evap Inch 1.15 2.65 2.95 5.78 4.02 6.69 6.13 5.36 3.73 2.44 1.34 1.8 44.04
 
Longmont South Avg. Temp F 30.17 33.48 34.87 51.4 55.64 70.46 76.54 69.19 62.6 43.49 37.01 33.37 49.85
Ref date as of 12/31/2002 Total Precip " 0.64 0.42 0.58 0.21 2.18 0.94 0.04 0.63 0.97 1.04 0.51 0.02 8.18
Site Type: Alfalfa Total Alfalfa ETr " 2.63 3.73 4.09 7.09 6.56 8.87 10.26 8.51 6.31 3.59 2.97 2.72 67.33
Total Growing Degee Days from March 1 0 0 96 266 309 539 689 579 425 172 83 53 3211
Gross Pond Evap Inch 2.21 3.13 3.44 5.96 5.51 7.45 8.62 7.15 5.3 3.02 2.49 2.28 56.56
Net Pond Evap Inch 1.76 2.84 3.03 5.81 3.98 6.79 8.59 6.71 4.62 2.29 2.14 2.27 50.83
 
Fort Collins NW Avg. Temp F 23.91 26.9 28.51 46.21 51.15 65.61 69.92 63.82 55.58 37.21 31.08 27.73 43.97
Ref date as of 12/30/2002 Total Precip " 0.44 0.07 0.34 0.29 1.88 0.5 0.01 0.77 1.64 0.46 0.48 0 6.88
Site Type: Turf Total Alfalfa ETr " 1.86 2.94 3.35 5.93 6.31 8.66 8.9 7.4 4.98 2.75 2.25 1.75 57.08
Total Growing Degee Days from March 1 0 0 73 230 288 545 674 562 386 146 61 30 2995
Gross Pond Evap Inch 1.56 2.47 2.81 4.98 5.3 7.27 7.48 6.22 4.18 2.31 1.89 1.47 47.94
Net Pond Evap Inch 1.25 2.42 2.58 4.78 3.98 6.92 7.47 5.68 3.04 1.99 1.55 1.47 43.13
 
Fort Collins Central Avg. Temp F #N/A #N/A #N/A 49.21 55.27 70.37 74.72 67.96 60.64 42 35.68 31.88 54.19
Ref date as of 12/31/2002 Total Precip " #N/A #N/A #N/A 0 1.87 0.72 0.19 0.4 1.47 0.72 0.38 0 5.75
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A 2.82 6.25 8.82 8.63 7.4 5.15 3.15 2.41 2.13 46.76
Total Growing Degee Days from March 1 0 0 #N/A 102 297 541 652 555 391 157 75 40 2810
Gross Pond Evap Inch #N/A #N/A #N/A 2.37 5.25 7.41 7.25 6.22 4.33 2.65 2.02 1.79 39.29
Net Pond Evap Inch #N/A #N/A #N/A 2.37 3.94 6.9 7.12 5.94 3.3 2.14 1.76 1.79 35.26
 
Windsor Avg. Temp F 23.97 27.19 28.06 45.78 51.55 65.78 71.21 64.37 57.36 38.57 31.75 27.39 44.42
Ref date as of 12/31/2002 Total Precip " 0.68 0.06 0.55 0.19 2.39 0.67 0.11 0.42 1.27 0.72 0.82 0 7.88
Site Type: Dryland Pasture Total Alfalfa ETr " 2.08 3.34 3.62 7.02 6.89 9.77 10.69 8.49 5.89 3.6 2.22 2.08 65.69
Total Growing Degee Days from March 1 0 0 86 262 321 562 692 583 416 172 66 30 3190
Gross Pond Evap Inch 1.75 2.81 3.04 5.9 5.79 8.21 8.98 7.13 4.95 3.02 1.86 1.75 55.19
Net Pond Evap Inch 1.27 2.76 2.66 5.76 4.11 7.74 8.9 6.84 4.06 2.52 1.29 1.75 49.66
 
Greeley West Avg. Temp F 25.51 31.12 32.56 50.65 56.63 71.73 75.96 69.18 62.35 42.88 35.32 31.24 48.76
Ref date as of 12/31/2002 Total Precip " 0.64 0.02 0.26 0.1 1.86 1.15 0.93 0.36 0.45 0.45 0.61 0.08 6.91
Site Type: Turf Total Alfalfa ETr " 1.62 2.94 3.58 6.93 7.11 9.7 9.63 8.06 5.92 3.43 2.21 1.91 63.04
Total Growing Degee Days from March 1 0 0 83 265 333 568 691 594 425 172 73 36 3240
Gross Pond Evap Inch 1.36 2.47 3.01 5.82 5.97 8.15 8.09 6.77 4.97 2.88 1.86 1.6 52.95
Net Pond Evap Inch 0.91 2.46 2.83 5.75 4.67 7.34 7.44 6.52 4.66 2.57 1.43 1.55 48.13
 
Loveland Avg. Temp F 28.85 32.49 33.64 50.77 55.54 71.36 76.76 69.55 62.24 43.03 35.79 32.47 49.37
Ref date as of 12/31/2002 Total Precip " 1.22 0.73 1.31 0.24 2.65 0.58 0.12 0.39 2.05 1.54 0.68 0.05 11.56
Site Type: Turf Total Alfalfa ETr " 2.14 3.15 3.49 6.2 6.5 8.66 8.94 7.48 5.21 3.01 2.23 1.97 58.98
Total Growing Degee Days from March 1 0 0 83 255 309 571 713 594 421 169 79 42 3236
Gross Pond Evap Inch 1.8 2.65 2.93 5.21 5.46 7.27 7.51 6.28 4.38 2.53 1.87 1.65 49.54
Net Pond Evap Inch 0.94 2.14 2.01 5.04 3.61 6.87 7.43 6.01 2.94 1.45 1.4 1.62 41.46
 
Berthoud 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 12/31/2004 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
 
Longmont West Avg. Temp F 30.38 33.35 34.71 51.61 55.88 71.23 76.88 69.4 62.8 43.59 37 33.43 50.02
Ref date as of 12/31/2002 Total Precip " 0.72 0.1 0.28 0.22 2.8 0.79 0.61 0.43 0.85 0.6 0.79 0 8.19
Site Type: Turf Total Alfalfa ETr " 1.86 2.71 3.36 5.83 5.94 8.05 8.41 6.89 4.88 2.73 1.89 1.57 54.12
Total Growing Degee Days from March 1 0 0 94 266 311 574 730 594 430 166 83 50 3298
Gross Pond Evap Inch 1.56 2.28 2.82 4.9 4.99 6.76 7.06 5.79 4.1 2.29 1.59 1.32 45.46
Net Pond Evap Inch 1.06 2.21 2.63 4.74 3.03 6.21 6.64 5.49 3.5 1.87 1.03 1.32 39.73
 
Fort Lupton 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 12/31/2006 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 NW Avg. Temp F #N/A #N/A #N/A 51.74 54.32 71.95 77.72 70.14 62.93 43.58 38.31 34.87 56.17
Ref date as of 12/31/2002 Total Precip " #N/A #N/A #N/A 0.17 2.87 1.28 0.03 0.96 1.82 1.07 1.01 0 9.21
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A 4.37 6.15 9.64 10.27 8.15 6.1 3.26 2.83 2.57 53.34
Total Growing Degee Days from March 1 0 0 #N/A 172 291 577 704 605 440 178 83 55 3105
Gross Pond Evap Inch #N/A #N/A #N/A 3.67 5.17 8.1 8.63 6.85 5.12 2.74 2.38 2.16 44.82
Net Pond Evap Inch #N/A #N/A #N/A 3.55 3.16 7.2 8.61 6.17 3.85 1.99 1.67 2.16 38.36
 
Boulder East Avg. Temp F 32.71 34.89 36.3 52.77 56.95 72.67 78.37 70.91 64.26 44.44 38.88 35.1 51.52
Ref date as of 12/31/2002 Total Precip " 0.63 0.18 0.52 0.16 3.18 1.15 0.24 0.37 1.38 1.1 0.79 0 9.7
Site Type: Turf Total Alfalfa ETr " 2.65 3.3 4.06 6.9 6.63 8.88 9.67 7.95 5.99 3.02 2.67 2.2 63.92
Total Growing Degee Days from March 1 0 0 86 266 311 588 744 619 440 160 80 50 3344
Gross Pond Evap Inch 2.23 2.77 3.41 5.8 5.57 7.46 8.12 6.68 5.03 2.54 2.24 1.85 53.7
Net Pond Evap Inch 1.79 2.65 3.05 5.68 3.34 6.65 7.95 6.42 4.07 1.77 1.69 1.85 46.91
 
Boulder Flatiron Avg. Temp F #N/A #N/A 39.85 50.03 53.92 67.57 71.67 65.89 60.29 41.59 36.71 32.61 52.01
Ref date as of 12/31/2002 Total Precip " #N/A #N/A 0.04 0.15 2.52 1.73 0.98 1.04 1.79 0.99 0.59 0 9.83
Site Type: Turf Total Alfalfa ETr " #N/A #N/A 1.53 5.48 5.22 6.64 6.89 5.57 4.12 2.22 2.05 1.74 41.46
Total Growing Degee Days from March 1 0 0 54 244 286 499 596 527 389 147 78 46 2866
Gross Pond Evap Inch #N/A #N/A 1.29 4.6 4.38 5.58 5.79 4.68 3.46 1.86 1.72 1.46 34.82
Net Pond Evap Inch #N/A #N/A 1.26 4.5 2.62 4.37 5.1 3.95 2.21 1.17 1.31 1.46 27.95
 
Boulder SW Avg. Temp F #N/A #N/A #N/A #N/A #N/A #N/A 77.81 70.06 63.73 44.48 40.51 37.23 55.64
Ref date as of 12/31/2002 Total Precip " #N/A #N/A #N/A #N/A #N/A #N/A 0.16 0.81 1.54 1.23 0.97 0.01 4.72
Site Type: Turf Total Alfalfa ETr " #N/A #N/A #N/A #N/A #N/A #N/A 9.7 8.09 6.51 3.27 3.48 3.28 34.33
Total Growing Degee Days from March 1 0 0 #N/A #N/A #N/A #N/A 761 598 446 144 70 44 2063
Gross Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A 8.15 6.8 5.47 2.75 2.92 2.76 28.85
Net Pond Evap Inch #N/A #N/A #N/A #N/A #N/A #N/A 8.04 6.23 4.39 1.89 2.24 2.75 25.54