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 2006 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 35.9 28.26 37.09 52.46 60.88 72.67 77.99 72.05 57.48 46.39 36.97 28.75 50.57
Ref date as of 12/31/2006 Total Precip " 0.72 0.42 0.85 1.12 1.12 1.41 0.58 1.7 1.41 0.89 0.11 0.98 11.31
Site Type: Alfalfa Total Alfalfa ETr " 3.95 3.35 4.51 7.73 9.54 10.76 12.05 8.58 6 4.65 3.88 2.64 77.64
Total Growing Degee Days from March 1 0 0 87 278 422 606 745 652 341 193 119 35 3478
Gross Pond Evap Total " 3.32 2.81 3.79 6.49 8.01 9.04 10.12 7.21 5.04 3.91 3.26 2.22 65.22
Net Pond Evap Total " 2.81 2.52 3.19 5.71 7.23 8.05 9.72 6.02 4.05 3.28 3.18 1.53 57.29
Crook Avg. Temp F 34.96 27.78 36.82 51.66 59.17 71.94 75.59 71.06 55.91 45.62 35.29 27.61 49.45
Ref date as of 12/31/2006 Total Precip " 0.42 0.24 0.45 0.53 1.06 0.97 0.49 1.47 0.54 0.62 0.05 0.3 7.14
Site Type: Alfalfa Total Alfalfa ETr " 3.9 3.31 4.19 7.22 8.12 9.79 9.52 7.4 5.18 4.26 3.5 2.2 68.59
Total Growing Degee Days from March 1 0 0 90 281 400 567 683 614 339 210 124 36 3344
Gross Pond Evap Inch 3.28 2.78 3.52 6.06 6.82 8.22 8 6.22 4.35 3.58 2.94 1.85 57.62
Net Pond Evap Inch 2.98 2.61 3.2 5.69 6.08 7.54 7.65 5.19 3.97 3.14 2.91 1.64 52.6
 
Sterling Avg. Temp F 34.25 28.11 37.72 51.72 59.9 72.38 75.53 71.06 56.22 45.76 35.74 26.09 49.54
Ref date as of 12/31/2006 Total Precip " 0.11 0.08 0.48 0.57 0.64 0.72 2.82 3.05 0.68 0.75 0.19 0.67 10.76
Site Type: Alfalfa Total Alfalfa ETr " 4.1 3.67 4.96 7.82 8.81 10.65 9.78 7.88 5.51 4.32 3.4 2.12 73.02
Total Growing Degee Days from March 1 0 0 112 296 401 582 692 634 344 221 123 33 3438
Gross Pond Evap Inch 3.44 3.08 4.17 6.57 7.4 8.95 8.22 6.62 4.63 3.63 2.86 1.78 61.35
Net Pond Evap Inch 3.37 3.03 3.83 6.17 6.95 8.44 6.24 4.48 4.15 3.1 2.72 1.31 53.79
 
Brush Avg. Temp F 34.29 29.16 38.42 52.17 60.24 72.8 75.55 71.55 56.78 46.67 36.48 25.92 50
Ref date as of 12/31/2006 Total Precip " 0.02 0.01 0.53 0.41 0.84 0.36 1.87 0.44 0.91 0.63 0.06 0.24 6.32
Site Type: Alfalfa Total Alfalfa ETr " 3.83 3.64 5.1 8.04 8.78 10.91 9.3 8.06 5.16 4.19 3.21 1.96 72.18
Total Growing Degee Days from March 1 0 0 125 304 415 595 705 641 351 238 120 28 3522
Gross Pond Evap Inch 3.22 3.06 4.28 6.75 7.38 9.16 7.81 6.77 4.33 3.52 2.7 1.65 60.63
Net Pond Evap Inch 3.2 3.05 3.91 6.47 6.79 8.91 6.5 6.46 3.7 3.08 2.65 1.48 56.2
 
Fort Morgan Avg. Temp F 34.11 29.02 37.65 51.86 60.23 72.47 75.46 71.52 57.06 46.48 36.2 25.65 49.81
Ref date as of 12/31/2006 Total Precip " 0.1 0.09 1.46 0.49 1.58 0.53 2.35 1.35 1.12 0.87 0.17 0.45 10.56
Site Type: Turf Total Alfalfa ETr " 3.45 3.29 4.59 7.34 8.48 9.83 9.15 7.7 5.24 3.95 2.83 1.68 67.53
Total Growing Degee Days from March 1 0 0 116 288 409 590 709 647 353 231 101 19 3463
Gross Pond Evap Inch 2.9 2.76 3.86 6.17 7.12 8.26 7.69 6.47 4.4 3.32 2.38 1.41 56.74
Net Pond Evap Inch 2.83 2.7 2.83 5.82 6.02 7.89 6.04 5.52 3.62 2.71 2.26 1.1 49.34
 
Wiggins Avg. Temp F 33.13 28 36.59 50.93 59.15 72.09 74.63 70.15 56.6 45.77 34.92 24.59 48.88
Ref date as of 12/31/2006 Total Precip " 0.08 0.07 0.7 0.44 0.45 0.11 1.7 0.55 0.53 0.42 0.05 0.29 5.39
Site Type: Alfalfa Total Alfalfa ETr " 3.57 3.26 5 7.89 8.27 10.88 9.95 7.98 5.9 4.29 3.04 1.75 71.78
Total Growing Degee Days from March 1 0 0 111 285 397 580 685 615 354 220 100 19 3366
Gross Pond Evap Inch 3 2.74 4.2 6.63 6.95 9.14 8.36 6.7 4.96 3.6 2.55 1.47 60.3
Net Pond Evap Inch 2.94 2.69 3.71 6.32 6.63 9.06 7.17 6.32 4.59 3.31 2.52 1.27 56.53
 
Fort Collins East Avg. Temp F 34.87 28.7 35.82 50.61 58.57 70 72.26 68.12 55.42 45.02 35.21 25.85 48.37
Ref date as of 12/31/2006 Total Precip " 0.1 0.37 0.93 0.37 0.79 0.15 0.78 0.44 0.83 1.28 0.25 0.57 6.86
Site Type: Alfalfa Total Alfalfa ETr " 4.07 3.4 4.36 7.85 7.92 9.8 8.12 7.06 5.36 3.8 2.95 1.88 66.57
Total Growing Degee Days from March 1 0 0 87 270 365 539 620 556 324 192 93 18 3064
Gross Pond Evap Inch 3.42 2.86 3.66 6.59 6.65 8.23 6.82 5.93 4.5 3.19 2.48 1.58 55.91
Net Pond Evap Inch 3.35 2.6 3.01 6.34 6.1 8.13 6.27 5.62 3.92 2.3 2.3 1.18 51.12
 
Eaton Avg. Temp F 33.87 28 35.99 50.32 58.38 70.46 72.81 68.17 55.59 45.11 35.05 26.12 48.32
Ref date as of 12/31/2006 Total Precip " 0.05 0.26 0.89 0.29 0.66 0.27 1.29 0.34 0.71 0.67 0.31 0.37 6.11
Site Type: Alfalfa Total Alfalfa ETr " 3.94 3.39 4.53 8.05 7.96 10.81 8.87 7.38 5.47 3.93 3 1.72 69.05
Total Growing Degee Days from March 1 0 0 96 270 366 550 642 559 327 196 92 17 3115
Gross Pond Evap Inch 3.31 2.85 3.81 6.76 6.69 9.08 7.45 6.2 4.59 3.3 2.52 1.44 58
Net Pond Evap Inch 3.27 2.67 3.18 6.56 6.22 8.89 6.55 5.96 4.1 2.83 2.3 1.19 53.72
 
Johnsons Corner Avg. Temp F 36.38 29.72 37.01 51.85 59.3 71.56 73.52 69.16 56.87 46.9 37.88 28.56 49.89
Ref date as of 12/31/2006 Total Precip " 0.09 0.31 0.79 0.26 0.74 0.13 2.12 1.59 0.36 1.43 0.39 1.36 9.57
Site Type: Alfalfa Total Alfalfa ETr " 4.01 3.29 4.36 7.71 8.12 10.5 9.11 7.26 5.24 3.98 3 1.89 68.47
Total Growing Degee Days from March 1 0 0 95 274 380 569 668 593 333 203 113 25 3253
Gross Pond Evap Inch 3.37 2.76 3.66 6.48 6.82 8.82 7.65 6.1 4.4 3.34 2.52 1.59 57.51
Net Pond Evap Inch 3.31 2.55 3.11 6.29 6.3 8.73 6.17 4.99 4.15 2.34 2.25 0.64 50.83
 
Gilcrest Avg. Temp F 34.36 27.96 36.76 50.87 58.84 71.46 73.32 69.76 56.23 46 35.2 23.53 48.69
Ref date as of 12/31/2006 Total Precip " 0.08 0.05 0.72 0.42 0.48 0.11 2 1.17 0.35 1.44 0.13 0.21 7.16
Site Type: Alfalfa Total Alfalfa ETr " 3.46 2.97 4.08 6.76 6.95 9.64 8.06 6.97 4.8 3.42 2.38 1.16 60.65
Total Growing Degee Days from March 1 0 0 104 276 381 567 673 614 347 208 97 10 3277
Gross Pond Evap Inch 2.91 2.49 3.43 5.68 5.84 8.1 6.77 5.85 4.03 2.87 2 0.97 50.94
Net Pond Evap Inch 2.85 2.46 2.92 5.38 5.5 8.02 5.37 5.04 3.79 1.86 1.91 0.83 45.93
 
Longmont South Avg. Temp F 38.84 31.78 38.23 52.91 60.3 71.63 73.89 69.46 56.93 48.07 39.37 30.09 50.96
Ref date as of 12/31/2006 Total Precip " 0.26 0.3 1 0.42 0.63 0.27 2.25 0.68 0.66 2.43 0.5 1.07 10.47
Site Type: Alfalfa Total Alfalfa ETr " 4.51 3.68 4.48 7.81 7.91 9.75 8.8 7.09 5.37 4.13 3.37 2.11 69.01
Total Growing Degee Days from March 1 0 0 105 284 389 567 669 597 334 213 113 32 3303
Gross Pond Evap Inch 3.79 3.09 3.76 6.56 6.64 8.19 7.39 5.96 4.51 3.47 2.83 1.77 57.96
Net Pond Evap Inch 3.61 2.88 3.06 6.27 6.2 8 5.82 5.48 4.05 1.77 2.48 1.02 50.64
 
Fort Collins NW Avg. Temp F 32.14 25.12 32.01 45 51.77 63.67 67.48 62.67 49.75 39.73 32.47 23.96 43.81
Ref date as of 12/31/2006 Total Precip " 0.08 0.06 0.78 0.21 0.86 0.26 0.8 1.1 0.59 1.84 0.31 0.11 7
Site Type: Turf Total Alfalfa ETr " 3.39 2.74 3.6 6.96 7.51 9.28 8.18 6.94 4.68 3.1 2.4 1.55 60.33
Total Growing Degee Days from March 1 0 0 78 259 379 555 650 583 317 183 94 24 3122
Gross Pond Evap Inch 2.85 2.3 3.02 5.85 6.31 7.8 6.87 5.83 3.93 2.6 2.02 1.3 50.68
Net Pond Evap Inch 2.79 2.26 2.48 5.7 5.71 7.61 6.31 5.06 3.52 1.32 1.8 1.23 45.79
 
Fort Collins Central Avg. Temp F 36.68 30.4 37.51 52.09 60 70.98 74.1 69.86 56.62 46.43 37.7 28.92 50.11
Ref date as of 12/31/2006 Total Precip " 0.09 0.2 0.81 0.22 0.84 0.16 0.82 1.35 0.58 2.13 0.37 0.37 7.94
Site Type: Turf Total Alfalfa ETr " 3.55 2.94 3.89 6.85 7.31 8.71 7.71 6.75 4.61 3.17 2.58 1.75 59.82
Total Growing Degee Days from March 1 0 0 91 269 384 561 666 601 333 205 112 33 3255
Gross Pond Evap Inch 2.98 2.47 3.27 5.75 6.14 7.32 6.48 5.67 3.87 2.66 2.17 1.47 50.25
Net Pond Evap Inch 2.92 2.33 2.7 5.6 5.55 7.2 5.9 4.73 3.47 1.17 1.91 1.21 44.69
 
Windsor Avg. Temp F 23.57 0 2.66 45.91 53.55 64.94 68.47 64.87 51.8 41.49 32.98 24.75 39.58
Ref date as of 12/31/2006 Total Precip " 0.06 0 0 0.14 0.56 0.19 1.09 0.58 0.25 1.79 0.36 1.23 6.25
Site Type: Dryland Pasture Total Alfalfa ETr " 3.09 0 0 0 4.47 10.5 9.06 7.96 5.35 3.74 2.75 1.48 48.4
Total Growing Degee Days from March 1 0 0 14 301 424 601 696 646 374 215 102 23 3396
Gross Pond Evap Inch 2.6 0 0 0 3.75 8.82 7.61 6.69 4.49 3.14 2.31 1.24 40.65
Net Pond Evap Inch 2.55 0 0 0 3.36 8.69 6.85 6.28 4.32 1.89 2.06 0.38 36.38
 
Greeley West Avg. Temp F 35.26 29.15 37.13 51.89 60.61 72.63 75.26 71.02 57.82 46.75 36.4 26.55 50.04
Ref date as of 12/31/2006 Total Precip " 0.01 0.07 0.68 0.33 0.43 0.15 1.85 0.96 0.56 1.43 0.15 0.3 6.92
Site Type: Turf Total Alfalfa ETr " 3.03 2.73 3.92 6.8 7.58 9.8 8.61 7.39 4.98 3.28 2.16 1.22 61.5
Total Growing Degee Days from March 1 0 0 95 279 404 605 702 638 354 208 89 20 3394
Gross Pond Evap Inch 2.55 2.29 3.29 5.71 6.37 8.23 7.23 6.21 4.18 2.76 1.81 1.02 51.65
Net Pond Evap Inch 2.54 2.24 2.82 5.48 6.07 8.13 5.94 5.54 3.79 1.75 1.71 0.81 46.82
 
Loveland Avg. Temp F 36.77 30.23 37.29 52.3 60.2 71.4 74.24 70.26 57.25 46.86 37.81 28.82 50.29
Ref date as of 12/31/2006 Total Precip " 0.07 0.09 0.83 0.15 0.59 0.15 1.64 1.59 0.25 2.02 0.28 0.29 7.95
Site Type: Turf Total Alfalfa ETr " 3.03 2.57 3.62 6.45 7.05 8.53 7.57 6.48 4.41 2.86 2.03 1.28 55.88
Total Growing Degee Days from March 1 0 0 91 266 388 584 687 625 336 196 95 28 3296
Gross Pond Evap Inch 2.55 2.16 3.04 5.42 5.92 7.17 6.36 5.44 3.7 2.4 1.71 1.08 46.95
Net Pond Evap Inch 2.5 2.1 2.46 5.31 5.51 7.06 5.21 4.33 3.53 0.99 1.51 0.87 41.38
 
Berthoud Avg. Temp F 37.28 29.89 37.13 52.23 60.16 71.7 74.26 70.07 57.51 47.41 38.16 29.68 50.46
Ref date as of 12/31/2006 Total Precip " 0.09 0.41 0.94 0.19 0.89 0.17 2.33 0.88 0.77 2.01 0.41 1.28 10.37
Site Type: Turf Total Alfalfa ETr " 3.91 3.12 4.19 7.59 8.42 10.19 9.14 7.62 5.64 4.01 2.89 2.08 68.8
Total Growing Degee Days from March 1 0 0 88 266 383 586 691 613 325 194 97 25 3268
Gross Pond Evap Inch 3.28 2.62 3.52 6.38 7.07 8.56 7.68 6.4 4.74 3.37 2.43 1.75 57.8
Net Pond Evap Inch 3.22 2.33 2.86 6.24 6.45 8.44 6.05 5.78 4.2 1.96 2.14 0.85 50.52
 
Longmont West Avg. Temp F 38.39 31.32 38.32 53.44 60.98 72.39 74.6 70.88 57.82 48.12 39.39 30.64 51.36
Ref date as of 12/31/2006 Total Precip " 0.14 0.05 0.82 0.25 0.82 0.34 2.9 1.51 0.6 2.31 0.24 0.65 10.63
Site Type: Turf Total Alfalfa ETr " 2.54 2.35 3.45 6.08 6.84 8.16 7.38 6.3 4.31 2.92 2.11 1.44 53.88
Total Growing Degee Days from March 1 0 0 93 281 402 610 709 640 340 209 113 33 3430
Gross Pond Evap Inch 2.13 1.97 2.9 5.11 5.75 6.85 6.2 5.29 3.62 2.45 1.77 1.21 45.25
Net Pond Evap Inch 2.04 1.94 2.32 4.93 5.17 6.62 4.17 4.24 3.2 0.84 1.6 0.75 37.82
 
Fort Lupton Avg. Temp F 36.8 29.57 37.07 51.54 59.99 71.83 74.35 70.44 57.1 47.28 37.96 28.18 50.18
Ref date as of 12/31/2006 Total Precip " 0.12 0.08 1.11 1.72 1.95 1.45 3.23 2.34 0.44 1.04 0.13 0.21 13.82
Site Type: Turf Total Alfalfa ETr " 4.07 3.66 4.61 7.61 8.91 10.91 9.72 8.51 6.03 4.6 3.33 2.16 74.12
Total Growing Degee Days from March 1 0 0 103 272 394 587 690 631 352 221 113 36 3399
Gross Pond Evap Inch 3.42 3.07 3.87 6.39 7.48 9.16 8.16 7.15 5.07 3.86 2.8 1.81 62.24
Net Pond Evap Inch 3.33 3.02 3.1 5.19 6.12 8.15 5.9 5.51 4.76 3.14 2.71 1.67 52.6
 
Boulder NW Avg. Temp F 39.63 32.63 37.63 52.97 61.2 72.46 74.6 70.87 57.52 49.02 41.47 33.71 51.98
Ref date as of 12/31/2006 Total Precip " 0.31 0.32 1.22 0.78 0.78 2 2.31 0.85 0.63 2.34 0.34 0.79 12.67
Site Type: Turf Total Alfalfa ETr " 4.06 3.28 3.9 7.08 8.19 9.35 8.9 7.48 5.24 4.01 3.34 2.17 67
Total Growing Degee Days from March 1 0 0 97 286 413 589 684 630 346 215 119 40 3419
Gross Pond Evap Inch 3.41 2.76 3.28 5.95 6.88 7.85 7.48 6.28 4.4 3.37 2.81 1.82 56.29
Net Pond Evap Inch 3.19 2.53 2.42 5.4 6.33 6.45 5.86 5.69 3.96 1.73 2.57 1.27 47.4
 
Boulder East Avg. Temp F 40.1 33.03 38.79 54.45 62.5 73.96 76.17 72.4 58.74 49.83 41.87 33.05 52.91
Ref date as of 12/31/2006 Total Precip " 0.22 0.15 1.17 0.62 0.7 1.02 2 0.65 0.59 3.2 0.1 0.92 11.34
Site Type: Turf Total Alfalfa ETr " 3.81 3.3 3.99 7.08 8.11 9.31 8.28 7.1 4.92 3.69 2.98 1.62 64.19
Total Growing Degee Days from March 1 0 0 94 282 417 619 719 663 345 219 118 44 3520
Gross Pond Evap Inch 3.2 2.77 3.35 5.95 6.81 7.82 6.96 5.96 4.13 3.1 2.5 1.36 53.91
Net Pond Evap Inch 3.05 2.67 2.53 5.51 6.32 7.11 5.56 5.51 3.72 0.86 2.43 0.72 45.99
 
Boulder Flatiron Avg. Temp F 38.11 31.59 37.18 51.84 59.39 69.64 72.15 68.53 55.33 47.32 39.2 30.69 50.08
Ref date as of 12/31/2006 Total Precip " 0.21 0.04 0.83 0.66 0.63 0.79 2.19 0.65 0.57 3.09 0.08 0.43 10.17
Site Type: Turf Total Alfalfa ETr " 3.05 2.76 3.55 5.96 6.36 7.03 6.15 5.03 3.76 2.66 2.34 1.49 50.14
Total Growing Degee Days from March 1 0 0 92 261 378 526 634 578 327 203 113 40 3152
Gross Pond Evap Inch 2.56 2.32 2.98 5.01 5.34 5.91 5.17 4.23 3.16 2.23 1.97 1.25 42.13
Net Pond Evap Inch 2.42 2.29 2.4 4.54 4.9 5.35 3.63 3.77 2.76 0.07 1.91 0.95 34.99
 
Boulder SW Avg. Temp F 41.42 34.07 38.37 53.29 60.69 71.63 74.26 70.45 58.05 49.95 42.88 35.79 52.57
Ref date as of 12/31/2006 Total Precip " 0.18 0.04 1.18 1.01 0.76 1.29 2.65 1.39 0.86 2.91 0.19 0.82 13.28
Site Type: Turf Total Alfalfa ETr " 4.85 3.88 4.24 7.31 8.13 9.15 8.25 7.02 5.21 4.27 3.8 2.85 68.96
Total Growing Degee Days from March 1 0 0 75 248 380 579 693 607 310 199 105 41 3237
Gross Pond Evap Inch 4.07 3.26 3.56 6.14 6.83 7.69 6.93 5.9 4.38 3.59 3.19 2.39 57.93
Net Pond Evap Inch 3.95 3.23 2.74 5.43 6.3 6.78 5.08 4.92 3.77 1.55 3.06 1.82 48.63