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 2008 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 23.45 30.6 38.7 46.39 55.78 66.6 75.32 70.15 60.46 49.08 39.21 23.48 48.27
Ref date as of 12/31/2008 Total Precip " 0.03 0.12 0.59 2.15 3.12 2.97 3.77 3.3 1.75 1.92 0.47 0.34 20.53
Site Type: Alfalfa Total Alfalfa ETr " 2 3.14 5.41 6.98 7.56 9.43 10.15 7.63 5.86 4.6 3.52 2.45 68.73
Total Growing Degee Days from March 1 0 0 99 195 310 497 694 609 408 266 118 33 3229
Gross Pond Evap Total " 1.68 2.64 4.54 5.86 6.35 7.92 8.53 6.41 4.92 3.86 2.96 2.06 57.73
Net Pond Evap Total " 1.66 2.55 4.13 4.36 4.17 5.84 5.89 4.1 3.7 2.52 2.63 1.82 43.37
Crook Avg. Temp F 22.06 30.62 38.77 46.81 55.63 66.13 73.64 69.79 59.51 48.63 38.9 21.99 47.71
Ref date as of 12/31/2008 Total Precip " 0.05 0.18 0.56 1.18 2.23 1.09 4.71 2.4 1.24 1.05 0.63 0.22 15.54
Site Type: Alfalfa Total Alfalfa ETr " 1.77 2.98 5.36 7.18 7.04 8.88 8.97 7.73 5.58 5.04 3.86 2.34 66.73
Total Growing Degee Days from March 1 0 0 105 200 309 477 667 607 387 257 110 27 3146
Gross Pond Evap Inch 1.49 2.5 4.5 6.03 5.91 7.46 7.53 6.49 4.69 4.23 3.24 1.97 56.04
Net Pond Evap Inch 1.45 2.38 4.11 5.21 4.35 6.7 4.24 4.81 3.82 3.5 2.8 1.81 45.18
 
Sterling Avg. Temp F 19.85 30.16 38.96 46.5 56.1 66.56 74.59 69.29 60.34 48.74 38.89 21.8 47.65
Ref date as of 12/31/2008 Total Precip " 0.13 0.26 0.44 0.82 0.61 1.3 2.09 3.72 0.96 0.72 0.63 0.3 11.98
Site Type: Alfalfa Total Alfalfa ETr " 1.46 2.53 5.33 7.28 8.06 9.53 10.33 7.71 6.43 5.04 3.61 2.09 69.4
Total Growing Degee Days from March 1 0 0 107 203 335 484 662 582 410 271 123 30 3207
Gross Pond Evap Inch 1.23 2.13 4.48 6.12 6.77 8.01 8.68 6.48 5.4 4.23 3.03 1.76 58.32
Net Pond Evap Inch 1.14 1.94 4.17 5.54 6.34 7.1 7.21 3.87 4.73 3.73 2.59 1.55 49.91
 
Brush Avg. Temp F 18.8 30.36 39.89 46.97 56.59 66.52 74.73 69.32 59.96 49.25 39.04 21.23 47.72
Ref date as of 12/31/2008 Total Precip " 0.1 0.13 0.17 0.4 1.32 2.93 2.02 3.06 1.04 0.3 0.27 0.27 12.01
Site Type: Alfalfa Total Alfalfa ETr " 1.51 2.47 5.38 7.18 7.81 8.9 10.29 7.51 5.7 5.22 3.71 1.85 67.53
Total Growing Degee Days from March 1 0 0 113 200 350 484 685 592 399 279 134 22 3258
Gross Pond Evap Inch 1.27 2.07 4.52 6.03 6.56 7.48 8.64 6.31 4.79 4.38 3.12 1.55 56.72
Net Pond Evap Inch 1.2 1.98 4.4 5.75 5.64 5.43 7.23 4.17 4.06 4.17 2.93 1.37 48.33
 
Fort Morgan Avg. Temp F 19.45 30.48 39.58 47.2 57.08 66.83 75.22 69.54 60.26 49.16 39.21 21.51 47.96
Ref date as of 12/31/2008 Total Precip " 0.21 0.23 0.31 0.92 1.5 1.59 2.67 6.02 1.43 0.52 0.47 0.48 16.35
Site Type: Turf Total Alfalfa ETr " 1.42 2.37 4.93 6.88 7.74 8.82 10 7.34 5.59 4.69 3.5 1.7 64.98
Total Growing Degee Days from March 1 0 0 107 203 349 491 684 598 400 265 126 21 3244
Gross Pond Evap Inch 1.19 1.99 4.14 5.78 6.5 7.41 8.4 6.17 4.7 3.94 2.94 1.43 54.59
Net Pond Evap Inch 1.05 1.83 3.92 5.14 5.45 6.3 6.53 1.95 3.69 3.58 2.61 1.09 43.14
 
Wiggins Avg. Temp F 18.18 30.51 39.34 46.69 56.47 67.25 75.07 69.13 59.77 48.79 38.68 19.98 47.49
Ref date as of 12/31/2008 Total Precip " 0.14 0.15 0.33 0.69 0.99 0.58 2.03 2.41 1.56 0.6 0.21 0.25 9.94
Site Type: Alfalfa Total Alfalfa ETr " 1.46 2.57 5.4 7.47 8.16 10.19 11.11 7.92 5.79 4.27 3.62 1.65 69.61
Total Growing Degee Days from March 1 0 0 109 198 336 501 680 578 386 258 133 19 3198
Gross Pond Evap Inch 1.23 2.16 4.54 6.27 6.85 8.56 9.33 6.65 4.86 3.59 3.04 1.39 58.47
Net Pond Evap Inch 1.13 2.05 4.31 5.79 6.16 8.15 7.91 4.97 3.77 3.17 2.89 1.21 51.51
 
Fort Collins East Avg. Temp F 24.34 32.31 38.39 45.65 54.86 64.76 71.84 66.68 57.35 47.65 40.09 23.86 47.32
Ref date as of 12/31/2008 Total Precip " 0 0.06 0.71 1.73 1.96 1.97 0.43 4.06 1.09 0.5 0.05 0.26 12.82
Site Type: Alfalfa Total Alfalfa ETr " 2.19 3.57 5.26 7.07 7.53 8.87 8.9 6.66 4.96 4.48 3.89 2.22 65.6
Total Growing Degee Days from March 1 0 0 87 175 302 452 616 511 336 234 123 29 2865
Gross Pond Evap Inch 1.84 3 4.42 5.94 6.33 7.45 7.48 5.59 4.17 3.76 3.27 1.86 55.11
Net Pond Evap Inch 1.84 2.96 3.92 4.73 4.95 6.07 7.18 2.75 3.4 3.41 3.23 1.68 46.12
 
Eaton Avg. Temp F 22.36 31.59 38.36 45.93 55.51 65.09 71.65 65.99 57.46 47.01 38.61 22.4 46.83
Ref date as of 12/31/2008 Total Precip " 0.04 0.13 0.59 0.53 1.13 1.78 0.56 4.09 1.98 0.8 0.17 0.26 12.06
Site Type: Alfalfa Total Alfalfa ETr " 1.88 3.31 5.42 7.36 7.75 8.51 8.57 6.23 5.03 4.09 3.47 1.86 63.48
Total Growing Degee Days from March 1 0 0 93 184 313 459 620 510 349 233 124 23 2908
Gross Pond Evap Inch 1.58 2.78 4.55 6.18 6.51 7.15 7.2 5.23 4.23 3.44 2.91 1.56 53.32
Net Pond Evap Inch 1.55 2.69 4.14 5.81 5.72 5.9 6.81 2.37 2.84 2.88 2.8 1.38 44.89
 
Johnsons Corner Avg. Temp F 24.29 33.53 39.29 46.54 55.78 65.76 74.24 67.77 58.94 49.29 41.26 24.45 48.43
Ref date as of 12/31/2008 Total Precip " 0.11 0.29 0.79 0.7 1.95 1.3 1.15 2.72 1.47 0.54 0.24 0.48 11.74
Site Type: Alfalfa Total Alfalfa ETr " 1.82 3.15 4.95 6.69 7.34 8.77 9.75 7.01 5.06 4.06 3.17 2.16 63.93
Total Growing Degee Days from March 1 0 0 93 184 315 476 653 544 358 230 127 30 3010
Gross Pond Evap Inch 1.53 2.65 4.16 5.62 6.17 7.37 8.19 5.89 4.25 3.41 2.66 1.81 53.71
Net Pond Evap Inch 1.45 2.44 3.61 5.13 4.8 6.46 7.39 3.98 3.22 3.03 2.49 1.48 45.48
 
Gilcrest Avg. Temp F 19.53 32.07 38.93 46.33 55.98 65.84 73.53 67.36 58.6 47.19 38.17 20.69 47.02
Ref date as of 12/31/2008 Total Precip " 0.05 0.26 0.57 0.6 2.17 1.28 0.36 4.8 1.66 2.16 0.17 0.34 14.42
Site Type: Alfalfa Total Alfalfa ETr " 1.46 2.86 4.93 7.05 7.03 8.83 9.57 6.86 5.14 3.84 3 1.73 62.3
Total Growing Degee Days from March 1 0 0 100 202 323 477 644 532 386 247 139 25 3075
Gross Pond Evap Inch 1.23 2.4 4.14 5.92 5.91 7.42 8.04 5.76 4.32 3.23 2.52 1.45 52.34
Net Pond Evap Inch 1.19 2.22 3.74 5.5 4.39 6.52 7.79 2.4 3.16 1.71 2.4 1.22 42.24
 
Longmont South Avg. Temp F 27.16 34.1 40.02 47.17 56.25 66.27 73.93 67.82 59.32 49.57 42.36 26.87 49.24
Ref date as of 12/31/2008 Total Precip " 0.13 0.32 0.79 0.52 2.14 1.25 0.04 2.36 1.54 0.35 0.35 0.59 10.38
Site Type: Alfalfa Total Alfalfa ETr " 2.59 3.37 5.28 6.86 7.14 9.25 9.7 7.12 5.41 4.41 3.7 2.52 67.35
Total Growing Degee Days from March 1 0 0 96 192 324 478 638 536 359 242 140 42 3047
Gross Pond Evap Inch 2.18 2.83 4.44 5.76 6 7.77 8.15 5.98 4.54 3.7 3.11 2.12 56.58
Net Pond Evap Inch 2.08 2.61 3.88 5.4 4.5 6.9 8.12 4.33 3.47 3.46 2.86 1.7 49.31
 
Fort Collins NW Avg. Temp F 25.18 32.98 38.56 46.17 56.02 65.92 74.14 67.73 58.88 48.57 40.98 24.96 48.34
Ref date as of 12/31/2008 Total Precip " 0.03 0.14 0.76 0.6 1.38 1.66 1.25 3.2 1.01 0.59 0.03 0.31 10.96
Site Type: Turf Total Alfalfa ETr " 1.81 2.79 3.4 4.88 5.73 6.77 6.77 4.81 3.64 2.69 2.76 1.75 47.8
Total Growing Degee Days from March 1 0 0 96 198 332 486 642 541 394 252 118 25 3084
Gross Pond Evap Inch 1.52 2.34 2.86 4.1 4.81 5.69 5.69 4.04 3.06 2.26 2.32 1.47 40.16
Net Pond Evap Inch 1.5 2.25 2.32 3.68 3.85 4.52 4.81 1.8 2.35 1.85 2.3 1.25 32.48
 
Fort Collins Central Avg. Temp F 26.18 33.83 39.32 47.05 56.07 66.25 73.68 67.74 58.8 48.97 41.87 26.15 48.83
Ref date as of 12/31/2008 Total Precip " 0.01 0.17 0.77 0.73 1.54 1.96 0.63 4.17 1.27 0.68 0.05 0.29 12.27
Site Type: Turf Total Alfalfa ETr " 2.18 3.12 4.53 6.49 6.79 8.13 8.38 5.72 4.28 3.3 2.85 1.87 57.64
Total Growing Degee Days from March 1 0 0 92 189 319 477 640 539 367 253 150 39 3065
Gross Pond Evap Inch 1.83 2.62 3.81 5.45 5.7 6.83 7.04 4.8 3.6 2.77 2.39 1.57 48.41
Net Pond Evap Inch 1.82 2.5 3.27 4.94 4.63 5.46 6.6 1.89 2.71 2.3 2.36 1.37 39.85
 
Windsor Avg. Temp F 24.39 33.47 39.63 47.41 57.03 67.19 75.63 68.87 59.98 49.78 41.47 24.08 49.08
Ref date as of 12/31/2008 Total Precip " 0.09 0.26 0.56 0.84 2.04 1.25 0.43 0.93 1.23 0.93 0.08 0.28 8.92
Site Type: Dryland Pasture Total Alfalfa ETr " 1.7 2.8 4.54 6.46 7.07 8.23 8.95 6.53 4.76 3.63 2.84 1.52 59.03
Total Growing Degee Days from March 1 0 0 105 211 356 511 676 576 389 258 137 26 3245
Gross Pond Evap Inch 1.43 2.35 3.81 5.43 5.94 6.91 7.52 5.49 4 3.05 2.39 1.28 49.6
Net Pond Evap Inch 1.37 2.17 3.42 4.84 4.51 6.04 7.22 4.83 3.14 2.4 2.33 1.08 43.35
 
Greeley West Avg. Temp F 22.45 32.4 39.26 46.54 56.17 66.17 74.32 67.76 58.88 48.31 39.35 22.23 47.82
Ref date as of 12/31/2008 Total Precip " 0.05 0.16 0.61 0.52 1.22 1.91 1.72 6.3 1.9 0.57 0.18 0.22 15.36
Site Type: Turf Total Alfalfa ETr " 1.46 2.79 4.66 6.67 7.48 8.58 9.28 6.74 5.08 3.74 2.8 1.45 60.73
Total Growing Degee Days from March 1 0 0 95 188 329 485 669 555 368 231 113 17 3050
Gross Pond Evap Inch 1.23 2.34 3.91 5.6 6.28 7.21 7.8 5.66 4.27 3.14 2.35 1.22 51.01
Net Pond Evap Inch 1.19 2.23 3.49 5.24 5.43 5.87 6.59 1.25 2.94 2.74 2.23 1.06 40.26
 
Loveland Avg. Temp F 26.15 33.55 39.2 47.23 56.32 66.19 74.33 68.76 59.91 49.44 41.5 25.77 49.03
Ref date as of 12/31/2008 Total Precip " 0.01 0.2 0.82 0.52 1.86 1.02 0.35 2.4 1.4 0.66 0.04 0.39 9.67
Site Type: Turf Total Alfalfa ETr " 2.02 2.87 4.55 6.43 6.89 8.14 8.17 5.97 4.51 3.17 2.28 1.6 56.6
Total Growing Degee Days from March 1 0 0 84 186 314 486 679 579 381 240 137 36 3122
Gross Pond Evap Inch 1.7 2.41 3.82 5.4 5.79 6.84 6.86 5.01 3.79 2.66 1.92 1.34 47.54
Net Pond Evap Inch 1.69 2.27 3.25 5.04 4.49 6.12 6.62 3.33 2.81 2.2 1.89 1.07 40.78
 
Berthoud Avg. Temp F 24.58 32.85 38.58 46.11 55.3 65.56 73.9 67.64 59.13 49.1 41.49 25.13 48.28
Ref date as of 12/31/2008 Total Precip " 0.06 0.3 1.06 0.62 2.98 1.5 1.07 4.11 1.86 0.52 0.24 0.37 14.69
Site Type: Turf Total Alfalfa ETr " 1.89 3.11 4.82 6.58 7.29 9.09 9.84 7.28 5.46 4.09 3.33 1.98 64.76
Total Growing Degee Days from March 1 0 0 81 174 298 468 667 538 340 214 134 27 2941
Gross Pond Evap Inch 1.59 2.61 4.05 5.53 6.12 7.64 8.27 6.12 4.59 3.44 2.8 1.66 54.42
Net Pond Evap Inch 1.55 2.4 3.31 5.09 4.04 6.59 7.52 3.24 3.28 3.07 2.63 1.4 44.12
 
Longmont West Avg. Temp F 27.31 34.49 40.32 47.77 56.82 67.28 75.31 68.84 59.63 48.87 41.59 26.56 49.57
Ref date as of 12/31/2008 Total Precip " 0 0.26 0.6 0.67 2.5 1.33 0.18 3.23 1.61 0.46 0.15 0.22 11.21
Site Type: Turf Total Alfalfa ETr " 1.74 2.41 3.91 5.67 6.48 7.84 8.18 6.61 4.8 3.29 2.6 1.98 55.51
Total Growing Degee Days from March 1 0 0 92 190 322 507 696 564 368 250 139 40 3168
Gross Pond Evap Inch 1.46 2.02 3.28 4.76 5.44 6.59 6.87 5.55 4.03 2.76 2.18 1.66 46.6
Net Pond Evap Inch 1.46 1.84 2.86 4.29 3.69 5.65 6.75 3.29 2.91 2.44 2.08 1.51 38.77
 
Fort Lupton Avg. Temp F 26.39 34.13 40.39 47.64 56.86 67.39 75.95 69.7 60.7 50.24 41.78 25.52 49.72
Ref date as of 12/31/2008 Total Precip " 0.02 0.21 0.39 0.32 1.94 1.34 0.51 5.23 1.6 0.86 0.18 0.1 12.7
Site Type: Turf Total Alfalfa ETr " 2.39 3.39 5.22 7.24 7.8 9.96 11.02 8.43 6.32 4.98 3.92 2.19 72.86
Total Growing Degee Days from March 1 0 0 106 202 331 509 698 598 396 273 147 43 3303
Gross Pond Evap Inch 2.01 2.85 4.38 6.08 6.55 8.37 9.26 7.08 5.31 4.18 3.29 1.84 61.2
Net Pond Evap Inch 1.99 2.7 4.11 5.86 5.19 7.43 8.9 3.42 4.19 3.58 3.17 1.77 52.31
 
Boulder NW Avg. Temp F 30.28 34.99 40.01 47.62 56.67 67.21 75.73 69.26 60.26 51.14 44.5 30.82 50.71
Ref date as of 12/31/2008 Total Precip " 0.08 0.43 0.63 0.72 2.05 1.46 0.21 2.29 1.33 1.04 0.15 0.75 11.14
Site Type: Turf Total Alfalfa ETr " 2.59 3.08 4.72 6.49 7.16 8.88 9.34 7.15 5.22 4.06 3.44 2.68 64.81
Total Growing Degee Days from March 1 0 0 94 198 336 509 683 588 394 261 150 51 3264
Gross Pond Evap Inch 2.18 2.59 3.96 5.45 6.01 7.46 7.85 6.01 4.38 3.41 2.89 2.25 54.44
Net Pond Evap Inch 2.12 2.29 3.52 4.95 4.58 6.44 7.7 4.4 3.45 2.68 2.78 1.73 46.64
 
Boulder East Avg. Temp F 29.76 35.32 41.29 48.77 57.89 68.91 77.91 70.97 61.53 51.35 26.63 30.25 50.05
Ref date as of 12/31/2008 Total Precip " 0.07 0.56 1.94 3.8 2.66 1.35 0.01 3.41 1.6 0.73 0.09 0.44 16.66
Site Type: Turf Total Alfalfa ETr " 2.7 3.08 4.91 6.6 7.18 8.62 9.03 6.73 4.78 3.49 1.43 2.54 61.09
Total Growing Degee Days from March 1 0 0 90 192 331 523 721 606 383 259 104 52 3261
Gross Pond Evap Inch 2.27 2.59 4.12 5.54 6.03 7.24 7.59 5.65 4.02 2.93 1.2 2.13 51.31
Net Pond Evap Inch 2.22 2.2 2.77 2.88 4.17 6.3 7.58 3.27 2.9 2.42 1.14 1.83 39.68
 
Boulder Flatiron Avg. Temp F 28.62 33.74 39.79 46.56 55.87 65.29 72.32 66.99 58.21 37.32 38.28 29.31 47.69
Ref date as of 12/31/2008 Total Precip " 0.1 0.31 0.64 0.77 3.26 1.36 0.06 3 2.12 0.8 0.09 0.37 12.88
Site Type: Turf Total Alfalfa ETr " 2.38 2.69 4.2 5.54 5.87 6.61 6.41 4.96 3.6 1.92 1.94 2.12 48.24
Total Growing Degee Days from March 1 0 0 86 186 304 457 616 520 352 164 111 48 2844
Gross Pond Evap Inch 2 2.26 3.53 4.65 4.93 5.55 5.38 4.17 3.02 1.61 1.63 1.78 40.51
Net Pond Evap Inch 1.93 2.04 3.08 4.11 2.65 4.6 5.34 2.07 1.54 1.05 1.57 1.52 31.5
 
Boulder SW Avg. Temp F 32.18 36.7 41.3 48.54 56.96 67.95 76.33 69.61 60.87 52.45 45.97 32.04 51.74
Ref date as of 12/31/2008 Total Precip " 0.07 0.42 0.88 0.87 3.35 1.17 0.03 2.78 1.87 1.01 0.15 0.57 13.17
Site Type: Turf Total Alfalfa ETr " 3.57 3.49 5.23 6.83 7.29 9.31 9.66 6.76 4.87 4.01 3.83 3.36 68.21
Total Growing Degee Days from March 1 0 0 78 169 307 511 737 583 357 230 138 49 3159
Gross Pond Evap Inch 3 2.93 4.39 5.74 6.12 7.82 8.11 5.68 4.09 3.37 3.22 2.82 57.29
Net Pond Evap Inch 2.95 2.64 3.78 5.13 3.78 7 8.09 3.73 2.78 2.66 3.11 2.42 48.07