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 2003 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 29.95 25.55 39.48 49.69 57.63 64.07 77.51 73.64 58.84 51.38 33.06 28.46 49.11
Ref date as of 12/31/2003 Total Precip " 0.25 0.45 1.33 2.33 2.01 1.88 2.49 1.05 1.51 0.17 0.33 0.2 14
Site Type: Alfalfa Total Alfalfa ETr " 3.14 2.28 4.81 6.11 6.66 7.89 11.4 9.5 6.69 6.61 3.09 2.51 70.69
Total Growing Degee Days from March 1 0 0 147 230 331 472 709 659 385 341 65 19 3358
Gross Pond Evap Total " 2.64 1.92 4.04 5.13 5.59 6.63 9.58 7.98 5.62 5.55 2.6 2.11 59.39
Net Pond Evap Total " 2.46 1.6 3.11 3.5 4.19 5.31 7.83 7.25 4.56 5.43 2.36 1.97 49.57
Crook Avg. Temp F 30.8 25.03 39.46 49.47 57.3 63.8 75.74 72.62 57.9 51.12 33.31 28.33 48.74
Ref date as of 12/31/2003 Total Precip " 0.16 0.32 1.83 1.99 1.74 3.79 1.54 1.05 0.7 0.07 0.21 0.12 13.52
Site Type: Alfalfa Total Alfalfa ETr " 3.56 2.41 4.95 6.06 6.43 7.32 10.03 8.78 6.24 6.71 3.02 2.46 67.97
Total Growing Degee Days from March 1 0 0 152 234 326 464 679 640 386 350 69 20 3320
Gross Pond Evap Inch 2.99 2.02 4.16 5.09 5.4 6.15 8.43 7.38 5.24 5.64 2.54 2.07 57.11
Net Pond Evap Inch 2.88 1.8 2.88 3.7 4.18 3.5 7.35 6.64 4.75 5.59 2.39 1.98 47.64
 
Sterling Avg. Temp F 30.89 26.04 40.06 49.93 57.6 63.66 75.86 72.5 57.3 50.59 32.96 27.27 48.72
Ref date as of 12/31/2003 Total Precip " 0.06 0.1 2.56 2.82 2.05 1.88 0.4 1.23 0.07 0.06 0.08 0.05 11.36
Site Type: Alfalfa Total Alfalfa ETr " 3.35 2.29 4.95 6.29 6.57 7.31 10.75 9.06 6.22 6.39 2.99 2.42 68.59
Total Growing Degee Days from March 1 0 0 155 235 325 458 676 640 382 345 69 25 3310
Gross Pond Evap Inch 2.81 1.92 4.16 5.28 5.52 6.14 9.03 7.61 5.22 5.37 2.51 2.03 57.6
Net Pond Evap Inch 2.77 1.85 2.37 3.31 4.08 4.82 8.75 6.75 5.18 5.33 2.46 2 49.67
 
Brush Avg. Temp F 32.05 26.9 40.4 50.76 57.72 63.01 76.75 73.73 59.66 51.89 33.6 28.15 49.55
Ref date as of 12/31/2003 Total Precip " 0.1 0.34 2.79 1.29 2.64 3.17 1.69 1.08 0.29 0.02 0.09 0.26 13.76
Site Type: Alfalfa Total Alfalfa ETr " 3.15 2.27 4.77 6.85 6.57 6.99 10.6 9.3 6.76 6.11 2.75 2.44 68.56
Total Growing Degee Days from March 1 0 0 150 246 338 445 688 662 413 350 73 34 3399
Gross Pond Evap Inch 2.65 1.91 4.01 5.75 5.52 5.87 8.9 7.81 5.68 5.13 2.31 2.05 57.59
Net Pond Evap Inch 2.58 1.67 2.05 4.85 3.67 3.65 7.72 7.06 5.48 5.12 2.25 1.87 47.97
 
Fort Morgan Avg. Temp F 32.3 27.49 40.88 51.3 58.99 63.95 76.85 73.4 59.21 51.78 33.24 27.58 49.75
Ref date as of 12/31/2003 Total Precip " 0.03 0.07 2.26 1.6 2.92 2.5 1.84 0.91 0.31 0.03 0.08 0.05 12.6
Site Type: Turf Total Alfalfa ETr " 3.04 2.3 4.61 6.67 7.15 7.29 10.36 8.69 6.1 5.78 2.53 2.36 66.88
Total Growing Degee Days from March 1 0 0 152 254 368 463 706 672 409 358 68 29 3479
Gross Pond Evap Inch 2.55 1.93 3.87 5.6 6.01 6.12 8.7 7.3 5.12 4.86 2.13 1.98 56.17
Net Pond Evap Inch 2.53 1.88 2.29 4.48 3.96 4.37 7.41 6.66 4.91 4.83 2.07 1.95 47.34
 
Wiggins Avg. Temp F 31.25 26.51 40.19 50.56 57.78 63.19 75.55 71.64 58.51 51.63 32.48 26.51 48.82
Ref date as of 12/31/2003 Total Precip " 0.03 0.43 1.48 1.87 1.62 1.97 1.88 0.36 0.07 0.01 0.2 0.26 10.18
Site Type: Alfalfa Total Alfalfa ETr " 2.94 2.38 4.55 6.96 6.47 6.97 9.86 8.12 5.98 5.89 2.5 2.2 64.82
Total Growing Degee Days from March 1 0 0 143 249 342 438 686 638 391 361 68 19 3335
Gross Pond Evap Inch 2.47 2 3.82 5.85 5.43 5.85 8.28 6.82 5.02 4.95 2.1 1.85 54.44
Net Pond Evap Inch 2.45 1.7 2.79 4.54 4.3 4.48 6.97 6.57 4.97 4.94 1.96 1.67 47.34
 
Fort Collins East Avg. Temp F 31.92 26.33 38.63 47.66 55.4 60.9 73.64 70.05 56.76 51.56 33.44 28.14 47.87
Ref date as of 12/31/2003 Total Precip " 0.04 0.31 0.96 2.32 1.94 1 0.02 1.28 0.19 0.1 0.35 0.2 8.71
Site Type: Alfalfa Total Alfalfa ETr " 3.29 2.37 4.72 5.82 6.44 6.6 9.51 8 6.13 6.53 2.7 2.57 64.68
Total Growing Degee Days from March 1 0 0 114 202 304 385 635 590 361 339 56 28 3014
Gross Pond Evap Inch 2.76 1.99 3.96 4.89 5.41 5.54 7.99 6.72 5.15 5.49 2.27 2.16 54.33
Net Pond Evap Inch 2.74 1.77 3.29 3.26 4.05 4.84 7.97 5.82 5.02 5.42 2.02 2.02 48.22
 
Eaton Avg. Temp F 32.16 26.88 39.52 48.77 56.34 61.67 73.34 69.35 56.74 50.54 33.23 27 47.96
Ref date as of 12/31/2003 Total Precip " 0.04 0.15 0.82 2.46 2.57 2.19 0.1 1.5 0.23 0.02 0.23 0.08 10.39
Site Type: Alfalfa Total Alfalfa ETr " 3.24 2.46 4.98 6.15 6.38 6.53 8.79 7.22 5.89 5.78 2.68 2.35 62.45
Total Growing Degee Days from March 1 0 0 134 222 325 402 647 592 367 329 62 19 3099
Gross Pond Evap Inch 2.72 2.07 4.18 5.17 5.36 5.49 7.38 6.06 4.95 4.86 2.25 1.97 52.46
Net Pond Evap Inch 2.69 1.96 3.61 3.44 3.56 3.95 7.31 5.01 4.79 4.84 2.09 1.92 45.17
 
Johnsons Corner Avg. Temp F 33.36 28.04 40.04 49 55.92 61.71 74.34 70.84 58.24 53.13 35.04 30 49.14
Ref date as of 12/31/2003 Total Precip " 0 0.23 2.05 0.2 2.3 1.01 0.37 1.74 0.18 0.02 0.29 0.13 8.52
Site Type: Alfalfa Total Alfalfa ETr " 2.85 2.12 4.58 5.82 5.66 6.45 9 7.82 5.81 5.64 2.68 2.32 60.75
Total Growing Degee Days from March 1 0 0 122 217 314 406 662 623 365 336 57 22 3124
Gross Pond Evap Inch 2.39 1.78 3.85 4.89 4.75 5.42 7.56 6.57 4.88 4.74 2.25 1.95 51.03
Net Pond Evap Inch 2.39 1.62 2.41 4.75 3.14 4.71 7.3 5.35 4.75 4.72 2.05 1.86 45.05
 
Gilcrest Avg. Temp F 31.83 27.66 40.06 49.42 57.74 63.18 74.31 70.51 57.92 51.3 33.49 27.1 48.71
Ref date as of 12/31/2003 Total Precip " 0 0.31 1.81 2.93 2.38 1.35 0.16 1.55 0.3 0.04 0.38 0.09 11.3
Site Type: Alfalfa Total Alfalfa ETr " 2.9 2.14 4.41 5.82 6.55 7.07 8.49 7.02 5.2 4.95 2.24 2.07 58.86
Total Growing Degee Days from March 1 0 0 129 229 351 435 663 614 388 353 64 32 3258
Gross Pond Evap Inch 2.44 1.8 3.7 4.89 5.5 5.94 7.13 5.9 4.37 4.16 1.88 1.74 49.45
Net Pond Evap Inch 2.44 1.58 2.44 2.84 3.84 4.99 7.02 4.81 4.16 4.13 1.62 1.68 41.55
 
Longmont South Avg. Temp F 36.83 29.3 42.37 50.08 56.75 62.31 74.81 71.28 58.37 54 36.46 31.42 50.33
Ref date as of 12/31/2003 Total Precip " 0.02 0.55 1.67 1.75 1.95 2.29 0.32 2.73 0.32 0.04 0.65 0.37 12.66
Site Type: Alfalfa Total Alfalfa ETr " 3.69 2.39 5.12 5.85 6.22 6.6 8.98 7.66 5.08 4.98 2.75 2.33 61.65
Total Growing Degee Days from March 1 0 0 136 219 327 411 658 615 374 350 62 41 3193
Gross Pond Evap Inch 3.1 2.01 4.3 4.91 5.22 5.54 7.54 6.43 4.27 4.18 2.31 1.96 51.77
Net Pond Evap Inch 3.09 1.62 3.13 3.69 3.86 3.94 7.32 4.52 4.04 4.16 1.86 1.7 42.93
 
Fort Collins NW Avg. Temp F 29.32 23.93 34.61 45.16 52.59 56.82 69.79 65.41 51.36 46.25 30.04 26.05 44.28
Ref date as of 12/31/2003 Total Precip " 0.02 0.34 2.02 2.23 2.22 1.36 0.37 2.85 0.16 0.03 0.45 0.24 12.29
Site Type: Turf Total Alfalfa ETr " 2.66 1.97 3.86 5.13 6.08 6.05 8.62 6.89 4.97 4.48 0.69 -4.53 51.4
Total Growing Degee Days from March 1 0 0 108 200 317 397 673 618 358 336 53 35 3095
Gross Pond Evap Inch 2.23 1.65 3.24 4.31 5.11 5.08 7.24 5.79 4.17 3.76 0.58 0 43.16
Net Pond Evap Inch 2.22 1.42 1.83 2.75 3.55 4.13 6.98 3.79 4.06 3.74 0.26 0 34.73
 
Fort Collins Central Avg. Temp F 34.62 28.61 40.26 49.51 57.17 62.51 76.17 71.64 58.4 52.71 35.54 31.12 49.86
Ref date as of 12/31/2003 Total Precip " 0.04 0.31 1.96 2.36 2.43 1.34 0.35 3.02 0.22 0.06 0.4 0.26 12.75
Site Type: Turf Total Alfalfa ETr " 2.89 2.22 4.14 5.32 6.31 6.19 8.67 7.07 5.15 4.78 2.29 2.12 57.15
Total Growing Degee Days from March 1 0 0 116 205 328 414 678 628 381 357 66 39 3212
Gross Pond Evap Inch 2.43 1.86 3.48 4.47 5.3 5.2 7.28 5.94 4.33 4.02 1.92 1.78 48.01
Net Pond Evap Inch 2.4 1.65 2.11 2.82 3.6 4.26 7.04 3.82 4.17 3.97 1.64 1.6 39.08
 
Windsor Avg. Temp F 29.35 23.47 34.15 43.23 52.39 58.44 71.93 68.61 54.31 49.28 31.73 27.06 45.33
Ref date as of 12/31/2003 Total Precip " 0.01 0.5 1.24 1.57 2.11 1.44 0.49 2.25 0.15 0 0.44 0.43 10.63
Site Type: Dryland Pasture Total Alfalfa ETr " 2.75 2.09 4.8 6.08 4.38 0 5.69 8.87 6.15 6.6 2.68 2.27 52.36
Total Growing Degee Days from March 1 0 0 119 208 336 461 720 674 423 380 71 26 3418
Gross Pond Evap Inch 2.31 1.76 4.03 5.11 3.68 0 4.78 7.45 5.17 5.54 2.25 1.91 43.99
Net Pond Evap Inch 2.3 1.41 3.16 4.01 2.2 0 4.44 5.88 5.06 5.54 1.94 1.61 37.55
 
Greeley West Avg. Temp F 33.29 28.38 40.64 50.22 58.19 63.38 77.29 72.87 59.31 53.09 34.41 28.39 49.96
Ref date as of 12/31/2003 Total Precip " 0.02 0.14 1.28 3.44 2.38 2.42 0.86 1.92 0.31 0.02 0.27 0.11 13.17
Site Type: Turf Total Alfalfa ETr " 2.47 2.15 4.42 6.05 6.82 6.93 9.7 8.23 5.79 5.07 2.24 1.78 61.65
Total Growing Degee Days from March 1 0 0 127 230 357 434 707 648 399 353 62 23 3340
Gross Pond Evap Inch 2.07 1.81 3.71 5.08 5.73 5.82 8.15 6.91 4.86 4.26 1.88 1.5 51.78
Net Pond Evap Inch 2.06 1.71 2.82 2.67 4.06 4.13 7.55 5.57 4.65 4.24 1.69 1.42 42.57
 
Loveland Avg. Temp F 35.05 28.95 41.41 50.2 57.69 62.6 76.98 72.76 59.03 53.63 35.91 31.25 50.46
Ref date as of 12/31/2003 Total Precip " 0.06 1 4.11 2.46 2.27 3.55 1.08 3.18 0.29 0.03 0.5 0.19 18.72
Site Type: Turf Total Alfalfa ETr " 2.61 2.15 4.14 5.36 5.99 6.05 8.39 7.09 4.93 4.33 2.08 1.94 55.06
Total Growing Degee Days from March 1 0 0 135 230 350 424 708 659 390 356 58 35 3345
Gross Pond Evap Inch 2.19 1.81 3.48 4.5 5.03 5.08 7.05 5.96 4.14 3.64 1.75 1.63 46.26
Net Pond Evap Inch 2.15 1.11 0.6 2.78 3.44 2.6 6.29 3.73 3.94 3.62 1.4 1.5 33.16
 
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 36.47 29.56 42.37 50.66 58.04 63.24 77.19 72.77 59.68 54.49 37.18 32.73 51.2
Ref date as of 12/31/2003 Total Precip " 0.03 0.44 2.21 1.73 2.43 1.96 0.23 2.72 0.18 0.03 0.4 0.22 12.58
Site Type: Turf Total Alfalfa ETr " 2.15 1.72 3.83 5.07 5.82 6.24 8.17 6.8 4.82 3.88 1.93 1.83 52.26
Total Growing Degee Days from March 1 0 0 132 222 348 426 725 672 390 359 64 41 3379
Gross Pond Evap Inch 1.81 1.44 3.22 4.26 4.89 5.24 6.86 5.71 4.05 3.26 1.62 1.54 43.9
Net Pond Evap Inch 1.79 1.14 1.67 3.05 3.19 3.87 6.7 3.81 3.92 3.24 1.34 1.38 35.1
 
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 38.2 28.85 42.25 50.41 57.39 62.58 77.65 72.91 59.95 55.78 37.6 34.21 51.48
Ref date as of 12/31/2003 Total Precip " 0.06 0.9 2.75 1.19 2.68 1.96 0.5 1.68 0.26 0.12 0.8 0.43 13.33
Site Type: Turf Total Alfalfa ETr " 3.17 2.04 4.69 5.96 6.62 6.46 10.19 8.3 5.99 5.41 2.77 2.58 64.18
Total Growing Degee Days from March 1 0 0 128 234 351 422 716 662 403 367 62 46 3391
Gross Pond Evap Inch 2.66 1.71 3.94 5.01 5.56 5.43 8.56 6.97 5.03 4.54 2.33 2.17 53.91
Net Pond Evap Inch 2.62 1.08 2.01 4.17 3.68 4.05 8.21 5.8 4.85 4.46 1.77 1.87 44.57
 
Boulder East Avg. Temp F 38.36 30.31 43.69 51.5 58.38 63.73 78.84 73.75 60.73 56.31 38.83 33.89 52.36
Ref date as of 12/31/2003 Total Precip " 0.03 0.71 2.39 1.54 2.27 1.13 0.38 2.5 0.32 0.07 0.56 0.41 12.31
Site Type: Turf Total Alfalfa ETr " 2.87 2.07 4.68 5.58 6.45 6.54 9.58 7.53 5.53 4.55 3 2.49 60.87
Total Growing Degee Days from March 1 0 0 125 211 341 421 736 677 393 353 71 47 3375
Gross Pond Evap Inch 2.41 1.74 3.93 4.69 5.42 5.49 8.05 6.33 4.65 3.82 2.52 2.09 51.14
Net Pond Evap Inch 2.39 1.24 2.26 3.61 3.83 4.7 7.78 4.58 4.42 3.77 2.13 1.8 42.51
 
Boulder Flatiron Avg. Temp F 36.04 28.91 42.14 49.07 55.71 61.01 72.03 68.79 56.6 51.62 36.02 31.7 49.14
Ref date as of 12/31/2003 Total Precip " 0.03 0.22 2.33 1.86 2.36 1.38 0.94 2.95 0.68 0.44 0.66 0.32 14.17
Site Type: Turf Total Alfalfa ETr " 2.35 1.75 3.91 4.53 5.18 5.05 6.48 5.32 3.95 3.52 1.84 1.97 45.85
Total Growing Degee Days from March 1 0 0 118 196 316 375 612 584 361 334 50 46 2992
Gross Pond Evap Inch 1.97 1.47 3.28 3.81 4.35 4.24 5.44 4.47 3.32 2.96 1.55 1.65 38.51
Net Pond Evap Inch 1.95 1.32 1.65 2.5 2.7 3.28 4.79 2.4 2.84 2.65 1.08 1.43 28.59
 
Boulder SW Avg. Temp F 40.06 30.09 43.41 50.24 57.23 61.78 76.74 72.16 60.46 57.04 39.34 36.61 52.1
Ref date as of 12/31/2003 Total Precip " 0.1 0.99 2.85 2.08 2.26 1.42 0.72 0.02 0 0.06 0.57 0.44 11.51
Site Type: Turf Total Alfalfa ETr " 3.69 2.29 5.18 5.52 6.32 6.06 9.12 7.72 5.59 5.34 3.2 3.3 63.33
Total Growing Degee Days from March 1 0 0 108 190 310 370 694 661 376 341 52 41 3143
Gross Pond Evap Inch 3.1 1.92 4.35 4.64 5.31 5.09 7.66 6.48 4.7 4.49 2.69 2.77 53.2
Net Pond Evap Inch 3.03 1.23 2.36 3.18 3.73 4.1 7.16 6.47 4.7 4.44 2.29 2.46 45.15