Pond Evaporation Calculation 1/31/24
Weather Station Data provided by Northern Colorado Water Conservancy District
See Weather Station Location Map at:
http://www.northernwater.org/WaterConservation/WeatherandETData.aspx
Notes:
Current month reflects values through "Reference Date".
Pond Evap. calculated per recent Division 1 Water Court decree language: Lower South Platte Home Page
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 2023 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec or Avg.
Ovid Avg. Temp F 21.35 23.01 32.33 47.37 60.85 67.86 73.73 72.83 65.29 47.86 38.23 32.11 48.57
Ref date as of 12/31/2023 Total Precip " 1.46 0.04 0.96 0.45 3.8 1.97 1.48 2.94 1.68 0.79 0.32 0.37 16.26
Site Type: Fully irrigated Total Alfalfa ETr " 0.81 1.48 3.22 7.5 7.1 7.74 9.16 9.23 7 4.96 4.01 2.78 64.99
Total Growing Degee Days from March 1 0 0 44 229 397 551 655 658 497 276 172 65 3544
Gross Pond Evap Total " 0.68 1.24 2.7 6.3 5.96 6.5 7.69 7.75 5.88 4.17 3.37 2.34 54.58
Net Pond Evap Total " 0 1.22 2.03 5.99 3.3 5.12 6.66 5.7 4.7 3.61 3.14 2.08 43.55
Crook Avg. Temp F 21.14 23.57 32.41 46.85 60.13 66.77 72.51 71.38 64.28 47.52 37.53 32.11 48.02
Ref date as of 12/31/2023 Total Precip " 0.97 0.1 0.48 0.46 5.53 5.96 3.67 1.6 0.82 0.49 0.24 0.23 20.55
Site Type: Fully irrigated Total Alfalfa ETr " 0.9 1.75 3.45 7.27 6.45 6.88 7.81 7.84 6.64 4.88 4.12 3.18 61.17
Total Growing Degee Days from March 1 0 0 43 222 384 519 638 620 485 279 171 61 3422
Gross Pond Evap Inch 0.76 1.47 2.9 6.11 5.42 5.78 6.56 6.59 5.58 4.1 3.46 2.67 51.4
Net Pond Evap Inch 0.08 1.4 2.56 5.78 1.55 1.61 3.99 5.47 5 3.76 3.29 2.51 37
 
Sterling Avg. Temp F 20.95 22.63 33.06 46.83 59.87 66.12 72.56 71.79 64.93 48.29 37.49 32.6 48.09
Ref date as of 12/31/2023 Total Precip " 1.28 0.12 0.67 0.71 5.11 6 2.46 1.89 0.24 0.27 0.21 0.11 19.07
Site Type: Fully irrigated Total Alfalfa ETr " 0.97 1.68 3.46 6.6 6.67 6.89 8.05 8.01 6.52 4.57 3.43 2.7 59.55
Total Growing Degee Days from March 1 0 0 45 220 371 493 642 629 494 281 172 69 3416
Gross Pond Evap Inch 0.81 1.41 2.91 5.54 5.6 5.79 6.76 6.73 5.48 3.84 2.88 2.27 50.02
Net Pond Evap Inch 0 1.33 2.44 5.05 2.03 1.59 5.04 5.41 5.31 3.65 2.73 2.19 36.77
 
Brush Avg. Temp F 18.73 21.3 33.97 46.43 59.15 65.3 71.84 71.39 63.38 48.28 35.98 31.66 47.28
Ref date as of 12/31/2023 Total Precip " 1.4 0.18 0.82 0.41 7.36 6.83 2.59 1.11 0.39 0.48 0.28 0.26 22.11
Site Type: Fully irrigated Total Alfalfa ETr " 0.98 1.76 3.93 6.8 6.72 6.72 7.41 8.22 5.67 4.85 3.06 2.75 58.87
Total Growing Degee Days from March 1 0 0 59 237 384 486 647 635 488 309 172 76 3493
Gross Pond Evap Inch 0.82 1.48 3.3 5.71 5.64 5.64 6.22 6.9 4.76 4.07 2.57 2.31 49.42
Net Pond Evap Inch 0 1.35 2.73 5.43 0.49 0.86 4.41 6.13 4.49 3.74 2.37 2.13 34.13
 
Fort Morgan Avg. Temp F 20.83 23.53 34.55 47.2 59.96 65.78 72.28 71.62 64.91 49.31 37.45 32.78 48.35
Ref date as of 12/31/2023 Total Precip " 0.85 0.09 0.73 0.64 7.36 6.22 3.62 1.74 0.42 0.82 0.24 0.2 22.93
Site Type: Fully irrigated Total Alfalfa ETr " 1 1.88 3.82 6.17 6.62 6.51 7.77 7.62 6.19 4.36 2.79 2.53 57.26
Total Growing Degee Days from March 1 0 0 59 224 383 492 649 637 490 299 165 69 3467
Gross Pond Evap Inch 0.84 1.58 3.21 5.18 5.56 5.47 6.53 6.4 5.2 3.66 2.34 2.13 48.1
Net Pond Evap Inch 0.25 1.52 2.7 4.73 0.41 1.11 3.99 5.18 4.91 3.09 2.18 1.99 32.06
 
Wiggins Avg. Temp F 19.05 21.29 33.49 45.77 58.43 64.7 70.9 69.82 63.29 47.88 36.69 33 47.03
Ref date as of 12/31/2023 Total Precip " 0.58 0.14 0.5 0.81 5.69 6.18 3.05 3.08 0.13 0.28 0.11 0.22 20.77
Site Type: Fully irrigated Total Alfalfa ETr " 0.99 1.78 4.12 6.6 6.83 7.17 8.29 7.88 6.57 4.98 3.2 2.91 61.32
Total Growing Degee Days from March 1 0 0 54 211 354 464 615 601 479 292 165 72 3307
Gross Pond Evap Inch 0.83 1.5 3.46 5.54 5.74 6.02 6.96 6.62 5.52 4.18 2.69 2.44 51.5
Net Pond Evap Inch 0.43 1.4 3.11 4.98 1.75 1.7 4.83 4.46 5.43 3.99 2.61 2.29 36.98
 
Fort Collins East Avg. Temp F 24.12 28.37 33.59 45.8 58.58 63.88 69.28 67.55 61.97 46.52 37.06 33.62 47.53
Ref date as of 12/31/2023 Total Precip " 0.62 0.2 0.54 0.65 3.52 5.9 2.69 2.86 0.71 0.54 0.33 4.91 23.47
Site Type: Fully irrigated Total Alfalfa ETr " 1.16 2.92 4.11 6.47 6.75 6.62 6.87 6.28 5.95 3.82 2.85 2.58 56.38
Total Growing Degee Days from March 1 0 0 44 203 357 437 564 560 461 259 140 62 3087
Gross Pond Evap Inch 0.97 2.45 3.45 5.43 5.67 5.56 5.77 5.28 5 3.21 2.39 2.17 47.35
Net Pond Evap Inch 0.54 2.31 3.07 4.98 3.21 1.43 3.89 3.27 4.5 2.83 2.16 0 32.19
 
Eaton Avg. Temp F 22.86 26.01 32.79 44.87 57.68 63.54 69.61 68.27 62.53 48.99 36.78 33.42 47.28
Ref date as of 12/31/2023 Total Precip " 0.89 0.32 2.37 0.91 4.45 2.67 2.36 0 0 0 0.54 0.15 14.66
Site Type: Fully irrigated Total Alfalfa ETr " 1.17 2.35 4.09 6.58 7.08 6.99 7.69 6.93 6.05 5.22 3.35 2.86 60.36
Total Growing Degee Days from March 1 0 0 39 192 343 441 583 568 475 288 145 57 3131
Gross Pond Evap Inch 0.98 1.97 3.44 5.53 5.95 5.87 6.46 5.82 5.08 4.38 2.81 2.4 50.69
Net Pond Evap Inch 0.36 1.75 1.78 4.89 2.83 4 4.81 5.82 5.08 4.38 2.44 2.3 40.44
 
Johnsons Corner Avg. Temp F 24.67 28.96 34.92 47.25 58.36 63.95 72.27 71.09 65.31 51.05 41.1 36.48 49.62
Ref date as of 12/31/2023 Total Precip " 0.97 0.35 0.67 0.82 4.29 4.16 1.64 2.49 1.29 0.61 0.63 0.11 18.03
Site Type: Fully irrigated Total Alfalfa ETr " 1.2 2.51 3.63 5.96 5.94 6.06 7.98 7.34 6.29 4.4 3.13 2.47 56.91
Total Growing Degee Days from March 1 0 0 43 195 329 437 638 624 485 277 146 61 3235
Gross Pond Evap Inch 1.01 2.11 3.05 5.01 4.99 5.09 6.7 6.17 5.28 3.7 2.63 2.07 47.81
Net Pond Evap Inch 0.33 1.86 2.58 4.43 1.99 2.18 5.56 4.42 4.38 3.27 2.19 2 35.19
 
Gilcrest Avg. Temp F 20.4 24.61 34.83 47.06 58.95 64.69 71.95 70.19 63.66 49.38 37.73 34.16 48.13
Ref date as of 12/31/2023 Total Precip " 0.68 0.28 0.7 1.06 5.97 5.27 2.07 2.54 0.61 0.45 0.31 0.08 20.02
Site Type: Fully irrigated Total Alfalfa ETr " 0.96 2.01 3.88 6.16 6.41 6.45 8.09 7.07 5.88 4.17 2.92 2.54 56.54
Total Growing Degee Days from March 1 0 0 53 215 359 454 630 602 484 284 156 70 3307
Gross Pond Evap Inch 0.81 1.69 3.26 5.17 5.38 5.42 6.8 5.94 4.94 3.5 2.45 2.13 47.49
Net Pond Evap Inch 0.33 1.49 2.77 4.43 1.21 1.73 5.35 4.16 4.51 3.19 2.24 2.08 33.49
 
Longmont South Avg. Temp F 24.25 29.73 34.96 47.1 57.4 62.92 71.15 70.17 63.32 49.5 39.67 35.64 48.82
Ref date as of 12/31/2023 Total Precip " 0.68 0.48 0.49 1.19 5.09 4.58 2.55 0.92 1.3 0.47 0.42 0.29 18.46
Site Type: Fully irrigated Total Alfalfa ETr " 1.29 2.72 4 6.07 5.69 5.83 7.83 6.89 5.67 4.22 2.94 2.25 55.4
Total Growing Degee Days from March 1 0 0 54 200 315 407 595 586 460 270 144 65 3096
Gross Pond Evap Inch 1.08 2.28 3.36 5.1 4.78 4.9 6.58 5.79 4.76 3.54 2.47 1.89 46.53
Net Pond Evap Inch 0.61 1.95 3.02 4.27 1.22 1.69 4.79 5.14 3.85 3.22 2.18 1.69 33.63
 
Fort Collins NW 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 5/2/2010 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
 
Fort Collins Central Avg. Temp F 26.27 29.37 34.56 46.13 58.61 63.67 70.58 69.56 63.11 48.75 38.65 35.39 48.72
Ref date as of 122823/0/2023 Total Precip " 0 0 0.37 0.83 3.52 4.48 4.58 3.1 0.6 0.07 0 0 17.55
Site Type: Fully irrigated Total Alfalfa ETr " 1.18 2.41 3.44 5.31 5.7 5.32 6.33 5.92 5.07 3.35 2.25 1.62 47.9
Total Growing Degee Days from March 1 0 0 40 188 345 381 584 582 467 282 149 64 3082
Gross Pond Evap Inch 0.99 2.02 2.89 4.46 4.79 4.47 5.32 4.97 4.26 2.81 1.89 1.36 40.23
Net Pond Evap Inch 0.99 2.02 2.63 3.88 2.32 1.33 2.11 2.8 3.84 2.77 1.89 1.36 27.94
 
Windsor 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 5/2/2010 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
 
Greeley West Avg. Temp F 24.03 27.01 34.77 47.34 59.24 65.14 72.95 71.79 65.68 50.58 39.04 33.83 49.28
Ref date as of 12/31/2023 Total Precip " 1.05 0.47 0.76 1.11 5.54 3.12 3.31 1.03 0.29 0.47 0.47 0.16 17.78
Site Type: Fully irrigated Total Alfalfa ETr " 0.83 1.78 3.49 5.29 5.73 5.4 6.42 6.31 4.76 3.6 1.84 1.88 47.33
Total Growing Degee Days from March 1 0 0 48 201 350 464 650 637 502 296 149 52 3349
Gross Pond Evap Inch 0.7 1.5 2.93 4.44 4.81 4.54 5.39 5.3 4 3.02 1.55 1.58 39.76
Net Pond Evap Inch 0 1.17 2.4 3.67 0.94 2.35 3.08 4.58 3.8 2.7 1.22 1.47 27.38
 
Loveland Avg. Temp F 24.82 29.1 94.88 46.88 58.51 64.74 71.98 70.57 64.1 49.12 38.76 34.87 54.03
Ref date as of 122823/0/2023 Total Precip " 1.1 0.66 0.84 1.14 3.34 4.68 2.19 3.23 1.32 0.74 0.58 0.19 20.01
Site Type: Fully irrigated Total Alfalfa ETr " 1.09 2.29 5.75 5.23 5.38 4.54 6.52 5.94 5.02 3.28 2.15 1.54 48.73
Total Growing Degee Days from March 1 0 0 880 237 360 356 635 622 496 299 162 63 4110
Gross Pond Evap Inch 0.92 1.92 4.83 4.39 4.52 3.81 5.48 4.99 4.22 2.76 1.81 1.29 40.94
Net Pond Evap Inch 0.15 1.46 4.24 3.6 2.18 0.54 3.94 2.73 3.29 2.24 1.4 1.16 26.93
 
Berthoud Avg. Temp F 25.17 29.53 35.42 47.87 59.46 64.96 73.39 71.98 66.2 51.5 41.41 36.28 50.26
Ref date as of 12/31/2023 Total Precip " 0.9 0.42 0.48 3.09 3.81 4.23 4.56 0 0 0 0.57 0.17 18.23
Site Type: Fully irrigated Total Alfalfa ETr " 0.97 2.13 4.41 5.42 5.91 6.3 7.67 6.72 5.42 3.39 2.14 1.89 52.37
Total Growing Degee Days from March 1 0 0 40 194 338 465 674 652 496 270 139 52 3320
Gross Pond Evap Inch 0.81 1.79 3.7 4.55 4.96 5.29 6.44 5.64 4.55 2.85 1.8 1.59 43.97
Net Pond Evap Inch 0.18 1.5 3.37 2.39 2.3 2.33 3.25 5.64 4.55 2.85 1.4 1.47 31.23
 
Longmont West Avg. Temp F 25.6 31.18 35.83 48.1 59.45 64.91 73.31 71.61 65.18 50.19 40.14 35.52 50.09
Ref date as of 12/31/2023 Total Precip " 0 0 0 0 0 0 0 0 0 0 0 0 0
Site Type: Fully irrigated Total Alfalfa ETr " 1.03 2.35 3.22 4.9 5.14 5.27 6.59 5.55 4.52 2.92 2.03 1.52 45.04
Total Growing Degee Days from March 1 0 0 51 199 334 450 650 626 489 282 149 67 3297
Gross Pond Evap Inch 0.87 1.97 2.7 4.12 4.32 4.43 5.54 4.66 3.8 2.45 1.71 1.28 37.85
Net Pond Evap Inch 0.87 1.97 2.7 4.12 4.32 4.43 5.54 4.66 3.8 2.45 1.71 1.28 37.85
 
Fort Lupton Avg. Temp F 23.59 28.96 35.03 47.51 58.14 64.07 72.65 71.67 65.39 50.62 41.13 36.43 49.6
Ref date as of 12/31/2023 Total Precip " 0.89 0.33 0.61 1.44 8.6 3.77 1.43 1.82 0.94 0.51 0.33 0.18 20.85
Site Type: Fully irrigated Total Alfalfa ETr " 1.28 2.74 4.09 6.54 6.45 6.88 8.89 8.32 6.87 4.77 3.55 2.88 63.26
Total Growing Degee Days from March 1 0 0 49 203 329 437 655 640 495 282 160 74 3324
Gross Pond Evap Inch 1.08 2.3 3.44 5.49 5.42 5.78 7.47 6.99 5.77 4.01 2.98 2.42 53.15
Net Pond Evap Inch 0.45 2.07 3.01 4.49 0 3.14 6.47 5.71 5.11 3.65 2.75 2.29 39.14
 
Boulder NW Avg. Temp F 27.75 32.61 35.02 47.12 57.72 63.15 72.32 71.03 64.83 49.94 42.42 36.9 50.07
Ref date as of 12/31/2023 Total Precip " 0 0 0 0 0 0 0 0 0 0 0 0 0
Site Type: Fully irrigated Total Alfalfa ETr " 1.47 2.84 3.47 5.52 5.64 5.68 7.42 6.47 5.43 3.31 2.82 1.81 51.88
Total Growing Degee Days from March 1 0 0 46 191 315 399 628 613 472 262 140 50 3116
Gross Pond Evap Inch 1.23 2.39 2.91 4.64 4.74 4.77 6.23 5.43 4.56 2.78 2.37 1.52 43.57
Net Pond Evap Inch 1.23 2.39 2.91 4.64 4.74 4.77 6.23 5.43 4.56 2.78 2.37 1.52 43.57
 
Boulder East 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 5/2/2010 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 Flatiron 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 5/2/2010 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 SW Avg. Temp F 29.56 34.76 36.11 47.88 58.32 63.7 72.87 71.72 65.91 51.73 44.69 39.64 51.41
Ref date as of 12/31/2023 Total Precip " 0 0 0 0 0 0 0 0 0 0 0 0 0
Site Type: Fully irrigated Total Alfalfa ETr " 1.92 3.5 3.88 5.63 5.38 5.78 7.58 6.63 5.64 3.58 3.1 2.62 55.24
Total Growing Degee Days from March 1 0 0 39 176 297 413 620 624 469 252 131 64 3085
Gross Pond Evap Inch 1.61 2.94 3.26 4.73 4.52 4.86 6.37 5.57 4.74 3.01 2.6 2.2 46.41
Net Pond Evap Inch 1.61 2.94 3.26 4.73 4.52 4.86 6.37 5.57 4.74 3.01 2.6 2.2 46.41
 
Greeley04 Avg. Temp F 20.98 24 34.41 46.73 58.68 64.51 71.01 69.85 63.76 49.31 36.46 32.67 47.7
Ref date as of 12/31/2023 Total Precip " 0.29 0.06 0.18 1.03 4.65 2.68 3.04 1.09 0.16 0.37 0.19 0.09 13.83
Site Type: Fully irrigated Total Alfalfa ETr " 0.95 1.86 4.34 6.54 7.26 7.34 8.14 7.95 6.82 4.86 2.85 2.63 61.54
Total Growing Degee Days from March 1 0 0 56 215 353 461 611 603 490 291 155 62 3297
Gross Pond Evap Inch 0.8 1.56 3.65 5.49 6.1 6.17 6.84 6.68 5.73 4.08 2.39 2.21 51.7
Net Pond Evap Inch 0.6 1.52 3.52 4.77 2.84 4.29 4.71 5.92 5.62 3.82 2.26 2.15 42.02