Pond Evaporation Calculation

3/5/26

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

2026

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

or Avg.

Ovid

Avg. Temp ° F

29.62

39.26

41.68

#N/A

36.85

Ref date as of 3/4/2026

Total Precip "

0.08

0.04

#N/A

0.12

Site Type: Fully irrigated

Total Alfalfa ETr "

3.76

5.14

0.64

#N/A

9.54

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Total "

3.16

4.32

0.54

#N/A

8.02

Net Pond Evap

Total "

3.1

4.29

0.54

#N/A

7.93

Crook

Avg. Temp ° F

29.45

39.1

42.23

#N/A

36.93

Ref date as of 3/4/2026

Total Precip "

0.05

0.07

0.08

#N/A

0.2

Site Type: Fully irrigated

Total Alfalfa ETr "

3.89

5.39

0.6

#N/A

9.88

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

3.27

4.53

0.5

#N/A

8.3

Net Pond Evap

Inch

3.23

4.48

0.45

#N/A

8.16

Sterling

Avg. Temp ° F

29.15

38.83

43.05

#N/A

37.01

Ref date as of 3/4/2026

Total Precip "

0.04

0.12

0.1

#N/A

0.26

Site Type: Fully irrigated

Total Alfalfa ETr "

3.44

4.86

0.57

#N/A

8.87

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.89

4.08

0.48

#N/A

7.45

Net Pond Evap

Inch

2.86

0.41

#N/A

7.27

Brush

Avg. Temp ° F

28.91

38.31

44.35

#N/A

37.19

Ref date as of 3/4/2026

Total Precip "

0.29

0.24

0.08

#N/A

0.61

Site Type: Fully irrigated

Total Alfalfa ETr "

3.38

4.79

0.6

#N/A

8.77

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.84

4.02

0.5

#N/A

7.36

Net Pond Evap

Inch

2.64

3.86

0.45

#N/A

6.95

Fort Morgan

Avg. Temp ° F

29.9

39.5

44.98

#N/A

38.13

Ref date as of 3/4/2026

Total Precip "

0.09

0.16

0.09

#N/A

0.34

Site Type: Fully irrigated

Total Alfalfa ETr "

3.14

4.18

0.53

#N/A

7.85

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.64

3.51

0.45

#N/A

6.6

Net Pond Evap

Inch

2.57

3.4

0.38

#N/A

6.35

Wiggins

Avg. Temp ° F

38.62

44.63

#N/A

37.42

Ref date as of 3/4/2026

Total Precip "

0.05

0.1

0.02

#N/A

0.17

Site Type: Fully irrigated

Total Alfalfa ETr "

3.44

4.71

0.63

#N/A

8.78

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.89

3.96

0.53

#N/A

7.38

Net Pond Evap

Inch

2.85

3.89

0.52

#N/A

7.26

Fort Collins East

Avg. Temp ° F

31.71

39.74

44.28

#N/A

38.58

Ref date as of 3/4/2026

Total Precip "

0.32

#N/A

0.32

Site Type: Fully irrigated

Total Alfalfa ETr "

3.52

4.6

0.57

#N/A

8.69

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.96

3.86

0.48

#N/A

7.3

Net Pond Evap

Inch

2.73

3.86

0.48

#N/A

7.07

Eaton

Avg. Temp ° F

30.46

38.92

44.28

#N/A

37.89

Ref date as of 3/4/2026

Total Precip "

0.26

0.05

0.27

#N/A

0.58

Site Type: Fully irrigated

Total Alfalfa ETr "

3.6

4.85

0.55

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

3.02

4.07

0.46

#N/A

7.55

Net Pond Evap

Inch

2.84

4.04

0.27

#N/A

7.15

Johnsons Corner

Avg. Temp ° F

33.15

43.11

45.83

#N/A

40.7

Ref date as of 3/4/2026

Total Precip "

0.32

0.02

#N/A

0.34

Site Type: Fully irrigated

Total Alfalfa ETr "

2.89

4.31

0.56

#N/A

7.76

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.43

3.62

0.47

#N/A

6.52

Net Pond Evap

Inch

2.2

3.62

0.46

#N/A

6.28

Gilcrest

Avg. Temp ° F

30.45

39.87

44.8

#N/A

38.37

Ref date as of 3/4/2026

Total Precip "

0.17

0.05

#N/A

0.22

Site Type: Fully irrigated

Total Alfalfa ETr "

2.99

4.19

0.57

#N/A

7.75

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.51

3.52

0.48

#N/A

6.51

Net Pond Evap

Inch

2.39

3.48

0.48

#N/A

6.35

Longmont South

Avg. Temp ° F

33.89

43.43

46.2

#N/A

41.17

Ref date as of 3/4/2026

Total Precip "

0.32

0.1

#N/A

0.42

Site Type: Fully irrigated

Total Alfalfa ETr "

2.93

4.6

0.54

#N/A

8.07

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.46

3.86

0.45

#N/A

6.77

Net Pond Evap

Inch

2.24

3.79

0.45

#N/A

6.48

Fort Collins NW

Avg. Temp ° F

#N/A

Ref date as of 5/2/2010

Total Precip "

#N/A

Site Type: Turf

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Fort Collins Central

Avg. Temp ° F

#N/A

Ref date as of 122823/0/2023

Total Precip "

#N/A

Site Type: Fully irrigated

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Windsor

Avg. Temp ° F

#N/A

Ref date as of 5/2/2010

Total Precip "

#N/A

Site Type: Turf

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Greeley West

Avg. Temp ° F

31.44

40.6

45.3

#N/A

39.11

Ref date as of 3/4/2026

Total Precip "

0.49

0.3

0.03

#N/A

0.82

Site Type: Fully irrigated

Total Alfalfa ETr "

2.28

3.12

0.45

#N/A

5.85

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

1.92

2.62

0.38

#N/A

4.92

Net Pond Evap

Inch

1.57

2.41

0.36

#N/A

4.34

Loveland

Avg. Temp ° F

#N/A

Ref date as of 122823/0/2023

Total Precip "

#N/A

Site Type: Fully irrigated

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Berthoud

Avg. Temp ° F

33.46

43.43

46.45

#N/A

41.11

Ref date as of 3/4/2026

Total Precip "

0.15

#N/A

0.15

Site Type: Fully irrigated

Total Alfalfa ETr "

2.45

3.76

0.47

#N/A

6.68

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.06

3.16

0.39

#N/A

5.61

Net Pond Evap

Inch

1.95

3.16

0.39

#N/A

5.5

Longmont West

Avg. Temp ° F

33.22

42.79

46.6

#N/A

40.87

Ref date as of 3/4/2026

Total Precip "

#N/A

Site Type: Fully irrigated

Total Alfalfa ETr "

3.06

0.44

#N/A

5.5

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

1.68

2.57

0.37

#N/A

4.62

Net Pond Evap

Inch

1.68

2.57

0.37

#N/A

4.62

Fort Lupton

Avg. Temp ° F

33.8

42.94

46.25

#N/A

Ref date as of 3/4/2026

Total Precip "

1.88

0.99

#N/A

2.87

Site Type: Fully irrigated

Total Alfalfa ETr "

3.41

4.59

0.58

#N/A

8.58

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.86

3.86

0.49

#N/A

7.21

Net Pond Evap

Inch

1.55

3.16

0.49

#N/A

5.2

Boulder NW

Avg. Temp ° F

35.67

43.23

45.23

#N/A

41.38

Ref date as of 3/4/2026

Total Precip "

#N/A

Site Type: Fully irrigated

Total Alfalfa ETr "

3.18

3.73

0.47

#N/A

7.38

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.67

3.13

0.39

#N/A

6.19

Net Pond Evap

Inch

2.67

3.13

0.39

#N/A

6.19

Boulder East

Avg. Temp ° F

#N/A

Ref date as of 5/2/2010

Total Precip "

#N/A

Site Type: Turf

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Boulder Flatiron

Avg. Temp ° F

#N/A

Ref date as of 5/2/2010

Total Precip "

#N/A

Site Type: Turf

Total Alfalfa ETr "

#N/A

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

#N/A

Net Pond Evap

Inch

#N/A

Boulder SW

Avg. Temp ° F

38.83

46.57

48.15

#N/A

44.52

Ref date as of 3/4/2026

Total Precip "

#N/A

Site Type: Fully irrigated

Total Alfalfa ETr "

4.08

4.56

0.5

#N/A

9.14

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

3.43

3.83

0.42

#N/A

7.68

Net Pond Evap

Inch

3.43

3.83

0.42

#N/A

7.68

Greeley04

Avg. Temp ° F

30.07

39.13

44.23

#N/A

37.81

Ref date as of 3/4/2026

Total Precip "

0.18

#N/A

0.18

Site Type: Fully irrigated

Total Alfalfa ETr "

3.01

4.04

0.55

#N/A

7.6

Total Growing Degee Days from March 1

#N/A

Gross Pond Evap

Inch

2.53

3.39

0.46

#N/A

6.38

Net Pond Evap

Inch

2.4

3.39

0.46

#N/A

6.25