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 2004 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 25.75 28.73 42.95 48.26 58.98 63.82 69.92 66.01 63.44 50.01 34.37 29.22 48.46
Ref date as of 12/31/2004 Total Precip " 0.17 0.82 0.26 2.6 2.32 1.86 3.42 3.96 1.64 0.98 0.47 0.1 18.6
Site Type: Alfalfa Total Alfalfa ETr " 2.65 2.63 5.96 6.15 8.3 8.2 8.12 6.9 7.23 3.77 2.43 2.58 64.92
Total Growing Degee Days from March 1 0 0 177 204 370 433 582 501 443 217 79 23 3029
Gross Pond Evap Total " 2.23 2.21 5.01 5.17 6.97 6.89 6.82 5.8 6.07 3.17 2.04 2.17 54.55
Net Pond Evap Total " 2.11 1.64 4.82 3.35 5.35 5.59 4.43 3.02 4.93 2.48 1.71 2.1 41.53
Crook Avg. Temp F 26.75 29.07 43.7 48.43 58.82 63.72 69.42 66.32 62.38 50.68 34.69 29.05 48.59
Ref date as of 12/31/2004 Total Precip " 0.12 0.63 0.09 2.26 1.58 1.88 5.1 0.98 1.92 0.68 0.48 0.1 15.82
Site Type: Alfalfa Total Alfalfa ETr " 2.68 2.53 5.99 5.91 7.6 7.46 7.94 7.3 6.38 4.12 2.47 2.29 62.67
Total Growing Degee Days from March 1 0 0 199 213 368 433 567 517 434 251 84 27 3093
Gross Pond Evap Inch 2.25 2.13 5.03 4.96 6.38 6.27 6.67 6.13 5.36 3.46 2.07 1.92 52.63
Net Pond Evap Inch 2.17 1.68 4.97 3.38 5.28 4.95 3.1 5.45 4.02 2.98 1.74 1.85 41.57
 
Sterling Avg. Temp F 26.53 29.46 44.27 48.53 58.93 63.4 70.73 66.36 62.49 50.15 33.81 28.36 48.59
Ref date as of 12/31/2004 Total Precip " 0.12 0.24 0.09 1.32 1.9 4.29 1.57 2.23 2.09 0.66 0.84 0.23 15.58
Site Type: Alfalfa Total Alfalfa ETr " 2.53 2.74 6.6 6.28 8.06 7.55 8.75 7.3 6.81 4.26 2.41 2.37 65.66
Total Growing Degee Days from March 1 0 0 209 212 374 438 579 523 437 251 75 27 3125
Gross Pond Evap Inch 2.13 2.3 5.54 5.28 6.77 6.34 7.35 6.13 5.72 3.58 2.02 1.99 55.15
Net Pond Evap Inch 2.04 2.13 5.48 4.35 5.44 3.34 6.25 4.57 4.26 3.12 1.44 1.83 44.25
 
Brush Avg. Temp F 27.45 29.88 45.49 49.14 59.83 63.67 70.48 66.95 62.51 50.29 33.48 27.73 48.91
Ref date as of 12/31/2004 Total Precip " 0.18 0.62 0.1 1.8 0.66 3.26 0.74 2.54 0.51 0.64 0.43 0.04 11.52
Site Type: Alfalfa Total Alfalfa ETr " 2.16 2.38 6.23 5.9 8.35 7.55 8.53 7.74 6.81 4.54 2.08 2.19 64.46
Total Growing Degee Days from March 1 0 0 226 225 400 439 589 536 446 262 74 28 3225
Gross Pond Evap Inch 1.81 2 5.23 4.96 7.01 6.34 7.17 6.5 5.72 3.81 1.75 1.84 54.14
Net Pond Evap Inch 1.69 1.57 5.16 3.7 6.55 4.06 6.65 4.72 5.36 3.37 1.45 1.81 46.09
 
Fort Morgan Avg. Temp F 26.71 29.47 45.26 49.45 60.29 63.96 70.77 67.34 62.84 50.66 34.13 28.09 49.08
Ref date as of 12/31/2004 Total Precip " 0.09 0.77 0.08 1.68 1.08 3.4 0.59 1.81 0.84 0.86 0.44 0.61 12.25
Site Type: Turf Total Alfalfa ETr " 1.94 2.19 5.87 5.95 8.32 7.31 8.39 7.68 6.46 4.38 2.09 2.09 62.67
Total Growing Degee Days from March 1 0 0 217 214 402 448 597 544 445 262 76 27 3232
Gross Pond Evap Inch 1.63 1.84 4.93 5 6.99 6.14 7.05 6.45 5.43 3.68 1.76 1.76 52.66
Net Pond Evap Inch 1.57 1.3 4.87 3.82 6.23 3.76 6.63 5.18 4.84 3.08 1.45 1.33 44.06
 
Wiggins Avg. Temp F 25.91 28.85 45.3 49.41 60.65 64.5 70.51 66.76 62.03 49.57 33.67 27.54 48.73
Ref date as of 12/31/2004 Total Precip " 0.38 0.56 0.02 1.44 1.18 1.91 1.82 1.05 1.02 0.69 0.63 0.11 10.81
Site Type: Alfalfa Total Alfalfa ETr " 1.74 2.12 6.45 6.13 8.77 7.93 8.22 7.38 6.13 4.15 1.99 2.02 63.03
Total Growing Degee Days from March 1 0 0 224 226 414 450 591 544 447 280 84 43 3303
Gross Pond Evap Inch 1.46 1.78 5.42 5.15 7.37 6.66 6.9 6.2 5.15 3.49 1.67 1.7 52.95
Net Pond Evap Inch 1.2 1.39 5.4 4.14 6.54 5.32 5.63 5.46 4.44 3 1.23 1.62 45.37
 
Fort Collins East Avg. Temp F 27.84 27.59 44.6 47.07 58.29 61.13 68.05 63.79 58.1 47.3 33.44 29.11 47.19
Ref date as of 12/31/2004 Total Precip " 0.55 0.27 0.2 1.19 1.19 1.97 1.3 2.07 2.15 0.9 0.35 0.08 12.22
Site Type: Alfalfa Total Alfalfa ETr " 2.47 2.34 6.38 5.62 7.63 5.61 7.78 6.63 5.72 3.77 2.4 2.47 58.82
Total Growing Degee Days from March 1 0 0 195 183 354 362 529 470 373 200 75 27 2768
Gross Pond Evap Inch 2.07 1.97 5.36 4.72 6.41 4.71 6.54 5.57 4.8 3.17 2.02 2.07 49.41
Net Pond Evap Inch 1.69 1.78 5.22 3.89 5.58 3.33 5.63 4.12 3.3 2.54 1.77 2.02 40.87
 
Eaton Avg. Temp F 27.22 28.06 44.9 47.56 58.42 62.14 68.15 64.05 59.25 48 33.77 29.2 47.56
Ref date as of 12/31/2004 Total Precip " 0.28 0.31 0.03 1.05 1.76 2.4 0.91 1.43 2.02 1.06 0.37 0.04 11.66
Site Type: Alfalfa Total Alfalfa ETr " 2.18 2.29 6.6 5.85 7.57 6.69 7.42 6.45 5.85 3.76 2.44 2.42 59.52
Total Growing Degee Days from March 1 0 0 206 191 360 384 547 481 392 207 77 29 2874
Gross Pond Evap Inch 1.83 1.92 5.54 4.91 6.36 5.62 6.23 5.42 4.91 3.16 2.05 2.03 49.98
Net Pond Evap Inch 1.64 1.71 5.52 4.18 5.13 3.94 5.6 4.42 3.5 2.42 1.79 2 41.85
 
Johnsons Corner Avg. Temp F 29.81 29.87 46.04 47.67 58.47 62.15 68.05 65 59.99 48.82 35.36 30.79 48.5
Ref date as of 12/31/2004 Total Precip " 0.19 0.21 0.27 1.5 1.21 2.53 1.79 1.54 2.79 0.72 0.99 0.1 13.84
Site Type: Alfalfa Total Alfalfa ETr " 2.24 2.14 6.18 5.48 7.43 6.85 7.36 6.82 5.85 3.64 2.14 2.14 58.27
Total Growing Degee Days from March 1 0 0 199 184 360 384 541 499 389 202 68 24 2850
Gross Pond Evap Inch 1.88 1.8 5.19 4.6 6.24 5.75 6.18 5.73 4.91 3.06 1.8 1.8 48.94
Net Pond Evap Inch 1.75 1.65 5 3.55 5.39 3.98 4.93 4.65 2.96 2.55 1.1 1.73 39.24
 
Gilcrest Avg. Temp F 27.25 29.17 45.55 48.2 60.43 62.85 68.98 65.16 60.02 48.23 33.96 27.56 48.11
Ref date as of 12/31/2004 Total Precip " 0.17 0.28 0.12 2.11 1.64 1.94 0.78 3.11 2.43 0.77 0.31 0.06 13.72
Site Type: Alfalfa Total Alfalfa ETr " 1.72 1.99 5.82 5.28 8.36 6.17 7.48 6.3 5.45 3.34 1.79 1.74 55.44
Total Growing Degee Days from March 1 0 0 212 195 402 405 579 520 409 230 77 28 3057
Gross Pond Evap Inch 1.44 1.67 4.89 4.44 7.02 5.18 6.28 5.29 4.58 2.81 1.5 1.46 46.56
Net Pond Evap Inch 1.33 1.48 4.8 2.96 5.87 3.82 5.74 3.12 2.88 2.27 1.29 1.42 36.98
 
Longmont South Avg. Temp F 31.07 31.53 47.12 47.4 59.06 61.86 69.04 65.44 60.8 49.8 37.29 33.46 49.49
Ref date as of 12/31/2004 Total Precip " 0.64 0.45 0.33 3.03 1.12 2.54 2.23 2.19 2.29 0.96 1.13 0.18 17.09
Site Type: Alfalfa Total Alfalfa ETr " 2.14 2.19 5.7 4.86 7.32 6.31 7.64 6.58 5.72 3.87 2.1 2.72 57.15
Total Growing Degee Days from March 1 0 0 209 171 368 379 553 501 395 215 81 40 2912
Gross Pond Evap Inch 1.8 1.84 4.79 4.08 6.15 5.3 6.42 5.53 4.8 3.25 1.76 2.28 48
Net Pond Evap Inch 1.35 1.52 4.56 1.96 5.36 3.52 4.86 3.99 3.2 2.58 0.97 2.16 36.03
 
Fort Collins NW Avg. Temp F 25.05 26.76 40.4 43.41 54.91 58.78 63.35 59.7 53.86 43.78 29.49 27.07 43.88
Ref date as of 12/31/2004 Total Precip " 0.15 0.21 0.42 1.57 1.23 2.34 2.65 2.64 2.58 0.56 0.47 0.24 15.06
Site Type: Turf Total Alfalfa ETr " 1.96 2.05 5.27 3.67 0.11 0 0 0 0 0.06 -0.6 0.76 13.88
Total Growing Degee Days from March 1 0 0 183 177 364 380 541 485 374 203 68 28 2803
Gross Pond Evap Inch 1.65 1.72 4.43 3.08 0.09 0 0 0 0 0.05 0 0.64 11.66
Net Pond Evap Inch 1.54 1.58 4.13 1.98 0 0 0 0 0 0 0 0.47 9.7
 
Fort Collins Central Avg. Temp F 30.67 31.49 46.51 48.45 60.01 62.83 69.42 65.63 59.88 49.36 35.66 31.77 49.31
Ref date as of 12/31/2004 Total Precip " 0.18 0.31 0.37 1.7 1.58 2.64 1.93 3.49 2.84 0.92 0.8 0.25 17.01
Site Type: Turf Total Alfalfa ETr " 2.15 2.19 5.37 5.01 6.92 5.83 6.69 5.71 4.84 3.3 1.94 2.11 52.06
Total Growing Degee Days from March 1 0 0 202 187 377 392 554 509 391 227 90 40 2969
Gross Pond Evap Inch 1.81 1.84 4.51 4.21 5.81 4.9 5.62 4.8 4.07 2.77 1.63 1.77 43.74
Net Pond Evap Inch 1.68 1.62 4.25 3.02 4.71 3.05 4.27 2.35 2.08 2.13 1.07 1.6 31.83
 
Windsor Avg. Temp F 26.2 27 41.72 45.42 57.1 60.1 65.98 61.99 56.26 45.71 31.81 28.05 45.61
Ref date as of 12/31/2004 Total Precip " 0.35 0.75 0.11 1.64 1.65 2.3 1.3 2.7 2.09 0.92 0.63 0.12 14.56
Site Type: Dryland Pasture Total Alfalfa ETr " 2.31 2.3 6.58 6.05 8.39 7.23 8.38 7.34 6.13 3.99 2.36 2.31 63.37
Total Growing Degee Days from March 1 0 0 232 220 420 441 617 571 437 251 86 33 3308
Gross Pond Evap Inch 1.94 1.93 5.53 5.08 7.05 6.07 7.04 6.17 5.15 3.35 1.98 1.94 53.23
Net Pond Evap Inch 1.7 1.41 5.45 3.93 5.89 4.46 6.13 4.28 3.69 2.71 1.54 1.86 43.05
 
Greeley West Avg. Temp F 28.52 29.67 46.26 48.73 60.43 63.62 70.61 67.12 61.56 49.3 35.05 30.03 49.24
Ref date as of 12/31/2004 Total Precip " 0.11 0.49 0.07 1.57 1.41 2.3 0.75 2.9 1.63 1.03 0.35 0.1 12.71
Site Type: Turf Total Alfalfa ETr " 1.67 1.95 5.62 5.45 7.93 6.89 7.83 7.09 5.79 3.45 1.72 1.79 57.18
Total Growing Degee Days from March 1 0 0 205 204 392 413 592 544 417 224 72 31 3094
Gross Pond Evap Inch 1.4 1.64 4.72 4.58 6.66 5.79 6.58 5.96 4.86 2.9 1.44 1.5 48.03
Net Pond Evap Inch 1.33 1.3 4.67 3.48 5.67 4.18 6.05 3.93 3.72 2.18 1.2 1.43 39.14
 
Loveland Avg. Temp F 30.42 30.51 46.5 48.5 60.07 62.8 69.74 66.47 60.99 50.07 35.73 31.38 49.43
Ref date as of 12/31/2004 Total Precip " 0.37 0.23 0.39 1.28 1.85 2.42 3.03 2.2 2.87 0.59 0.77 0.18 16.18
Site Type: Turf Total Alfalfa ETr " 1.62 1.83 5.07 4.85 7.12 6.02 6.51 5.9 4.68 3.2 1.54 1.54 49.88
Total Growing Degee Days from March 1 0 0 199 180 381 401 581 535 405 215 76 22 2995
Gross Pond Evap Inch 1.36 1.54 4.26 4.07 5.98 5.06 5.47 4.96 3.93 2.69 1.29 1.29 41.9
Net Pond Evap Inch 1.1 1.38 3.99 3.18 4.69 3.36 3.35 3.42 1.92 2.28 0.75 1.17 30.59
 
Berthoud Avg. Temp F 30.55 30.66 46.55 48.1 59.98 62.86 69.81 66.25 61.29 49.55 36.18 31.75 49.46
Ref date as of 12/31/2004 Total Precip " 0.21 0.26 0.34 1.77 1.24 2.75 3.51 1.91 2.08 0.22 0.64 0.04 14.97
Site Type: Turf Total Alfalfa ETr " 2.14 2.21 5.94 5.6 8.41 7.37 8.41 7.28 6.23 3.78 2.15 2.21 61.73
Total Growing Degee Days from March 1 0 0 195 180 382 404 588 527 392 199 65 25 2957
Gross Pond Evap Inch 1.8 1.86 4.99 4.7 7.06 6.19 7.06 6.12 5.23 3.18 1.81 1.86 51.86
Net Pond Evap Inch 1.65 1.67 4.75 3.47 6.2 4.27 4.61 4.78 3.78 3.02 1.36 1.83 41.39
 
Longmont West Avg. Temp F 31.3 32.13 47.72 48.69 60.45 63.3 70.23 66.8 61.74 50.31 36.67 33.31 50.22
Ref date as of 12/31/2004 Total Precip " 0.27 0.55 0.38 2.39 1.08 3.18 2.39 1.42 2.17 0.95 0.92 0.16 15.86
Site Type: Turf Total Alfalfa ETr " 1.56 1.87 4.62 4.58 6.59 5.92 6.69 5.85 4.76 2.94 1.51 1.78 48.67
Total Growing Degee Days from March 1 0 0 207 179 389 406 594 535 409 212 80 39 3050
Gross Pond Evap Inch 1.31 1.57 3.88 3.85 5.54 4.97 5.62 4.91 4 2.47 1.27 1.5 40.89
Net Pond Evap Inch 1.12 1.19 3.61 2.17 4.78 2.75 3.95 3.92 2.48 1.8 0.62 1.38 29.77
 
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 33.75 31.67 47.31 47.5 60.22 63.11 70.01 65.91 62.17 49.84 37.21 35.52 50.35
Ref date as of 12/31/2004 Total Precip " 0.4 1.06 0.71 4.57 1.16 4.39 3.16 3.28 1.51 2.38 1.21 0.38 24.21
Site Type: Turf Total Alfalfa ETr " 2.58 2.17 5.59 4.86 7.81 7.01 8.01 6.8 6.09 3.96 1.98 2.83 59.69
Total Growing Degee Days from March 1 0 0 209 180 397 423 581 528 424 223 80 40 3085
Gross Pond Evap Inch 2.17 1.82 4.7 4.08 6.56 5.89 6.73 5.71 5.12 3.33 1.66 2.38 50.15
Net Pond Evap Inch 1.89 1.08 4.2 0.88 5.75 2.82 4.52 3.42 4.06 1.66 0.82 2.11 33.21
 
Boulder East Avg. Temp F 33.85 33.71 49.13 49.03 61.68 64.61 71.53 67.8 63.65 51.4 38.18 35.23 51.65
Ref date as of 12/31/2004 Total Precip " 0.33 0.84 0.59 3.86 1.5 3.32 2.84 2.77 1.79 1.62 0.99 0.14 20.59
Site Type: Turf Total Alfalfa ETr " 2.3 2.3 5.64 4.98 7.76 7 7.56 6.51 5.69 3.71 1.81 2.55 57.81
Total Growing Degee Days from March 1 0 0 214 175 398 433 609 544 418 213 80 41 3125
Gross Pond Evap Inch 1.93 1.93 4.74 4.18 6.52 5.88 6.35 5.47 4.78 3.12 1.52 2.14 48.56
Net Pond Evap Inch 1.7 1.34 4.32 1.48 5.47 3.56 4.36 3.53 3.53 1.98 0.83 2.04 34.14
 
Boulder Flatiron Avg. Temp F 31.8 31.79 46.74 47.24 59.07 61.91 68.36 64.63 59.67 48.93 36.28 33.5 49.16
Ref date as of 12/31/2004 Total Precip " 0.28 0.62 0.43 4.28 1.12 3.8 2.83 2.5 2.22 1.42 0.79 0.24 20.53
Site Type: Turf Total Alfalfa ETr " 2.01 1.97 4.72 4.06 6.04 5.27 5.61 4.71 3.79 2.57 1.44 1.96 44.15
Total Growing Degee Days from March 1 0 0 206 165 370 390 539 491 392 206 77 38 2874
Gross Pond Evap Inch 1.69 1.65 3.96 3.41 5.07 4.43 4.71 3.96 3.18 2.16 1.21 1.65 37.08
Net Pond Evap Inch 1.49 1.22 3.66 0.41 4.29 1.77 2.73 2.21 1.63 1.16 0.66 1.48 22.71
 
Boulder SW Avg. Temp F 35.95 33.87 48.84 48.11 60.55 62.51 69.82 66.59 63 51.51 39.2 37.93 51.49
Ref date as of 12/31/2004 Total Precip " 0.3 0.88 0.46 4.34 1.25 3.78 3.66 2.42 1.84 2.12 0.99 0.29 22.33
Site Type: Turf Total Alfalfa ETr " 3.21 2.52 6.05 4.88 7.67 6.5 7.07 6.41 5.84 4.32 2.33 3.46 60.26
Total Growing Degee Days from March 1 0 0 192 151 368 391 578 515 415 196 67 40 2913
Gross Pond Evap Inch 2.7 2.12 5.08 4.1 6.44 5.46 5.94 5.38 4.91 3.63 1.96 2.91 50.63
Net Pond Evap Inch 2.49 1.5 4.76 1.06 5.57 2.81 3.38 3.69 3.62 2.14 1.26 2.7 34.98