Pond Evaporation Calculation													11/2/11
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	2009	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	or Avg.
Ovid	Avg. Temp ° F	29.88	33.91	38.5	46.79	59.16	65.27	70.65	68.59	60.95	40.39	38.76	18.46	47.61
Ref date as of 12/31/2009	Total Precip "	0.36	0.5	0.31	3.72	3.31	6.43	3.42	3.98	2.16	2.15	0.23	0.39	26.96
Site Type: Alfalfa	Total Alfalfa ETr "	4.06	3.27	5.9	5.78	7.68	7.18	8.26	7.64	5.97	3.09	3.31	1.35	63.49
Total Growing Degee Days from March 1		0	0	165	175	346	481	627	581	421	111	115	6	3028
Gross Pond Evap	Total "	3.41	2.75	4.96	4.86	6.45	6.03	6.94	6.42	5.01	2.6	2.78	1.13	53.34
Net Pond Evap	Total "	3.16	2.4	4.74	2.25	4.13	1.53	4.54	3.63	3.5	1.09	2.62	0.86	34.45
Crook	Avg. Temp ° F	29.41	33.24	37.87	45.74	58.04	64.69	70.12	68.06	59.7	40.35	37.73	18.57	46.96
Ref date as of 12/31/2009	Total Precip "	0.21	0.53	0.15	2.88	2.76	5.43	1.57	2.23	2.34	1.49	0.24	0.28	20.11
Site Type: Alfalfa	Total Alfalfa ETr "	3.96	3.24	5.88	5.6	7.05	6.71	8.04	7.63	5.32	3.29	3.36	1.52	61.6
Total Growing Degee Days from March 1		0	0	164	158	330	466	610	568	399	114	116	9	2934
Gross Pond Evap	Inch	3.33	2.72	4.94	4.7	5.92	5.64	6.75	6.41	4.47	2.76	2.82	1.28	51.74
Net Pond Evap	Inch	3.18	2.35	4.83	2.69	3.99	1.84	5.65	4.85	2.83	1.72	2.65	1.08	37.66
Sterling	Avg. Temp ° F	30.07	34.34	38.7	46.18	58.57	65.63	70.81	68.82	60.43	41.24	38.11	19.74	47.72
Ref date as of 12/31/2009	Total Precip "	0.43	0.87	0.57	1.8	1.96	3.51	1.4	3	2.58	2.21	0.28	0.35	18.96
Site Type: Alfalfa	Total Alfalfa ETr "	3.79	3.67	5.86	5.81	7.29	6.87	8.49	8.15	5.49	3.32	3.34	1.56	63.64
Total Growing Degee Days from March 1		0	0	174	174	344	482	625	583	394	127	127	11	3041
Gross Pond Evap	Inch	3.18	3.08	4.92	4.88	6.12	5.77	7.13	6.85	4.61	2.79	2.81	1.31	53.45
Net Pond Evap	Inch	2.88	2.47	4.52	3.62	4.75	3.31	6.15	4.75	2.81	1.24	2.61	1.07	40.18
Brush	Avg. Temp ° F	29.91	34.65	39.09	46.5	58.72	64.89	70.44	68.75	60.76	41.73	37.48	20.37	47.77
Ref date as of 12/31/2009	Total Precip "	0.05	0.12	0.11	1.77	1.61	3.98	4.54	0.92	1.56	1.78	0.51	0.47	17.42
Site Type: Alfalfa	Total Alfalfa ETr "	3.29	3.7	5.76	5.85	7.12	6.94	8.36	7.9	6.01	3.53	2.93	1.58	62.97
Total Growing Degee Days from March 1		0	0	168	184	351	484	639	588	414	130	121	14	3093
Gross Pond Evap	Inch	2.76	3.11	4.84	4.91	5.98	5.83	7.02	6.64	5.05	2.97	2.46	1.33	52.9
Net Pond Evap	Inch	2.73	3.02	4.76	3.68	4.85	3.04	3.84	5.99	3.96	1.72	2.1	1	40.69
Fort Morgan	Avg. Temp ° F	29.79	34.83	39.46	46.6	59.31	64.94	70.29	68.85	61.3	41.88	37.52	20.66	47.95
Ref date as of 12/31/2009	Total Precip "	0.15	0.25	0.47	3.11	2.51	5.58	6.48	0.75	1.6	1.74	0.5	0.58	23.72
Site Type: Turf	Total Alfalfa ETr "	3.08	3.46	5.35	5.64	7.33	6.68	7.79	7.4	5.7	3.16	2.65	1.48	59.72
Total Growing Degee Days from March 1		0	0	160	178	356	485	633	580	418	131	117	14	3072
Gross Pond Evap	Inch	2.59	2.91	4.49	4.74	6.16	5.61	6.54	6.22	4.79	2.65	2.23	1.24	50.17
Net Pond Evap	Inch	2.48	2.73	4.17	2.56	4.4	1.71	2.01	5.69	3.67	1.44	1.88	0.84	33.58
Wiggins	Avg. Temp ° F	29.08	34.24	38.75	46.02	58.48	64.31	69.76	68.37	60.76	41.33	36.61	19.94	47.3
Ref date as of 12/31/2009	Total Precip "	0.08	0.11	0.17	2.38	1.36	4.9	2.06	1.06	1.27	1.48	0.6	0.46	15.93
Site Type: Alfalfa	Total Alfalfa ETr "	3.15	3.87	6.12	6.1	7.86	7.03	8.23	7.95	6.4	3.43	2.68	1.46	64.28
Total Growing Degee Days from March 1		0	0	161	182	351	470	607	565	412	128	116	7	2999
Gross Pond Evap	Inch	2.65	3.25	5.14	5.12	6.6	5.91	6.91	6.68	5.38	2.88	2.25	1.23	54
Net Pond Evap	Inch	2.59	3.17	5.02	3.46	5.65	2.48	5.47	5.94	4.49	1.85	1.83	0.9	42.85
Fort Collins East	Avg. Temp ° F	31.68	34.53	39.46	44.95	57.66	62.34	67.88	66.54	59.09	40.39	36.78	20.07	46.78
Ref date as of 12/31/2009	Total Precip "	0.15	0.09	0.45	3.34	1.77	4.25	1.71	0.21	0.6	1.41	0.53	0.76	15.27
Site Type: Alfalfa	Total Alfalfa ETr "	3.68	3.63	5.77	5.44	7.09	6.31	7.38	7.13	5.52	3.53	2.81	1.36	59.65
Total Growing Degee Days from March 1		0	0	140	164	320	408	548	516	381	117	112	4	2710
Gross Pond Evap	Inch	3.09	3.05	4.85	4.57	5.96	5.3	6.2	5.99	4.64	2.97	2.36	1.14	50.12
Net Pond Evap	Inch	2.99	2.99	4.53	2.23	4.72	2.33	5	5.84	4.22	1.98	1.99	0.61	39.43
Eaton	Avg. Temp ° F	29.98	34.16	38.84	45.41	57.9	62.25	66.4	64.42	58.05	39.09	34.77	18.84	45.84
Ref date as of 12/31/2009	Total Precip "	0.14	0.07	0.31	2.86	1.98	3.61	1.57	1.56	0.67	1.04	0.45	0.7	14.96
Site Type: Alfalfa	Total Alfalfa ETr "	3.54	3.82	6.01	5.84	7.17	6.41	7.02	6.53	5.55	3.29	2.53	1.3	59.01
Total Growing Degee Days from March 1		0	0	143	171	331	415	520	496	371	106	98	4	2655
Gross Pond Evap	Inch	2.97	3.21	5.05	4.91	6.02	5.38	5.9	5.49	4.66	2.76	2.13	1.09	49.57
Net Pond Evap	Inch	2.88	3.16	4.83	2.9	4.64	2.86	4.8	4.39	4.19	2.04	1.81	0.6	39.1
Johnsons Corner	Avg. Temp ° F	33.05	36.48	41.11	45.6	57.67	62.66	68.89	67.09	60.54	40.36	38.22	20.91	47.72
Ref date as of 12/31/2009	Total Precip "	0.31	0.34	0.63	3.09	1.84	2.78	3.34	0.49	1.03	1.37	0.55	0.84	16.61
Site Type: Alfalfa	Total Alfalfa ETr "	3.36	3.54	5.58	5.01	6.58	6.1	7.69	7.05	5.61	3.13	2.56	1.35	57.56
Total Growing Degee Days from March 1		0	0	148	163	329	421	580	531	393	111	105	3	2784
Gross Pond Evap	Inch	2.82	2.97	4.69	4.21	5.53	5.12	6.46	5.92	4.71	2.63	2.15	1.13	48.34
Net Pond Evap	Inch	2.61	2.74	4.25	2.05	4.24	3.18	4.12	5.58	3.99	1.67	1.77	0.55	36.75
Gilcrest	Avg. Temp ° F	30.07	34.66	39.83	45.74	58.5	63.47	68.53	67.08	60.01	40.42	36.09	19.24	46.97
Ref date as of 12/31/2009	Total Precip "	0.1	0.06	0.48	3.54	1.37	4.18	3.85	2.25	1.01	1.43	0.62	0.63	19.52
Site Type: Alfalfa	Total Alfalfa ETr "	3.16	3.66	5.98	5.19	6.87	6.54	7.44	7.19	5.41	2.94	2.25	1.17	57.8
Total Growing Degee Days from March 1		0	0	164	176	362	448	588	547	408	123	101	4	2921
Gross Pond Evap	Inch	2.65	3.07	5.02	4.36	5.77	5.49	6.25	6.04	4.54	2.47	1.89	0.98	48.53
Net Pond Evap	Inch	2.58	3.03	4.69	1.88	4.81	2.57	3.55	4.46	3.84	1.47	1.46	0.54	34.88
Longmont South	Avg. Temp ° F	35.06	37.32	42.06	46.14	58.32	62.97	68.68	68.25	61.05	41.78	39.88	22.6	48.68
Ref date as of 12/31/2009	Total Precip "	0.22	0.16	0.84	2.84	1.92	1.97	1.32	0.12	0.43	1.81	0.72	0.99	13.34
Site Type: Alfalfa	Total Alfalfa ETr "	4.21	4.02	6.1	5.3	7.13	6.5	7.59	7.47	5.56	3.31	2.86	1.56	61.61
Total Growing Degee Days from March 1		0	0	149	164	333	422	569	547	390	120	122	8	2824
Gross Pond Evap	Inch	3.54	3.38	5.12	4.45	5.99	5.46	6.38	6.27	4.67	2.78	2.4	1.31	51.75
Net Pond Evap	Inch	3.38	3.26	4.54	2.46	4.65	4.08	5.45	6.19	4.37	1.51	1.9	0.62	42.41
Fort Collins NW	Avg. Temp ° F	33.15	35.39	40.04	44.81	57.41	61.62	67.95	66.68	59.58	40.31	38.21	21.38	47.21
Ref date as of 12/31/2009	Total Precip "	0.09	0.1	0.34	2.45	1.9	4.45	3.17	0.12	0.53	0.72	0.54	0.24	14.65
Site Type: Turf	Total Alfalfa ETr "	2.82	2.54	4.26	4.27	6.13	5.7	6.78	6.21	4.75	2.62	2.09	0.99	49.16
Total Growing Degee Days from March 1		0	0	130	156	322	389	552	515	383	106	106	4	2663
Gross Pond Evap	Inch	2.37	2.13	3.58	3.59	5.15	4.79	5.7	5.22	3.99	2.2	1.76	0.83	41.31
Net Pond Evap	Inch	2.31	2.06	3.34	1.87	3.82	1.67	3.48	5.13	3.62	1.7	1.38	0.66	31.04
Fort Collins Central	Avg. Temp ° F	34.05	36.77	41.52	46.3	58.75	62.58	68.61	67.04	59.81	40.72	38.41	21.6	48.01
Ref date as of 12/31/2009	Total Precip "	0.04	0.13	0.37	2.46	1.81	4.87	3.17	0.22	0.67	1.05	0.53	0.36	15.68
Site Type: Turf	Total Alfalfa ETr "	2.92	2.99	4.76	4.54	6.36	5.95	6.66	6.13	4.71	2.67	2.2	1.11	51
Total Growing Degee Days from March 1		0	0	150	175	338	415	559	527	397	122	131	9	2823
Gross Pond Evap	Inch	2.45	2.51	4	3.81	5.34	5	5.59	5.15	3.96	2.24	1.85	0.93	42.83
Net Pond Evap	Inch	2.42	2.42	3.74	2.09	4.08	1.59	3.38	5	3.49	1.51	1.48	0.68	31.88
Windsor	Avg. Temp ° F	32.5	36.39	41.22	46.16	58.85	63.58	69.73	14.96	38.96	41.48	38.87	21.75	42.04
Ref date as of 12/27/2009	Total Precip "	0.17	0.18	0.72	4.03	2.42	2.48	3.16	0.1	1.05	1.41	0.67	0.38	16.77
Site Type: Dryland Pasture	Total Alfalfa ETr "	2.63	3.08	5.02	4.66	6.32	6.04	7.18	1.13	3.06	2.68	2.02	0.83	44.65
Total Growing Degee Days from March 1		0	0	158	187	362	446	603	174	243	131	109	3	2416
Gross Pond Evap	Inch	2.21	2.59	4.22	3.91	5.31	5.07	6.03	0.95	2.57	2.25	1.7	0.7	37.51
Net Pond Evap	Inch	2.09	2.46	3.71	1.09	3.61	3.34	3.82	0.88	1.84	1.26	1.23	0.43	25.76
Greeley West	Avg. Temp ° F	30.36	35.06	40.05	45.45	58.27	63.24	69.05	67.89	60.55	40.5	36.7	19.91	47.25
Ref date as of 12/31/2009	Total Precip "	0.04	0.05	0.24	3.16	2.19	3.17	3.64	1.32	0.87	0.69	0.26	0.08	15.71
Site Type: Turf	Total Alfalfa ETr "	2.61	3.07	5.09	4.94	6.77	6.56	7.61	6.97	5.28	2.74	1.87	0.91	54.42
Total Growing Degee Days from March 1		0	0	145	171	339	441	595	553	407	111	97	3	2862
Gross Pond Evap	Inch	2.19	2.58	4.28	4.15	5.69	5.51	6.39	5.85	4.44	2.3	1.57	0.76	45.71
Net Pond Evap	Inch	2.16	2.54	4.11	1.94	4.15	3.29	3.84	4.93	3.83	1.82	1.39	0.71	34.71
Loveland	Avg. Temp ° F	33.26	36.44	41.73	46.28	58.75	63.68	69.71	69.07	62.02	41.75	39.84	22.75	48.77
Ref date as of 12/31/2009	Total Precip "	0.04	0.17	0.32	3.27	2.29	1.99	2.1	0.99	1.18	0.8	0.45	0.41	14.01
Site Type: Turf	Total Alfalfa ETr "	2.56	2.74	4.87	4.65	6.57	6.22	7.05	6.41	5.07	2.75	2.05	1.09	52.03
Total Growing Degee Days from March 1		0	0	150	177	345	435	607	586	435	128	127	7	2997
Gross Pond Evap	Inch	2.15	2.3	4.09	3.91	5.52	5.22	5.92	5.38	4.26	2.31	1.72	0.92	43.7
Net Pond Evap	Inch	2.12	2.18	3.87	1.62	3.92	3.83	4.45	4.69	3.43	1.75	1.41	0.63	33.9
Berthoud	Avg. Temp ° F	33.64	36.58	41.02	45.48	58.02	62.85	68.78	67.5	60.31	39.76	37.87	20.68	47.71
Ref date as of 12/31/2009	Total Precip "	0.17	0.39	0.66	4.16	1.94	1.86	3.85	0.11	1.04	1.46	0.52	0.94	17.1
Site Type: Turf	Total Alfalfa ETr "	3.23	3.27	5.34	4.87	6.9	6.59	7.62	7.07	5.41	2.87	2.18	1.18	56.53
Total Growing Degee Days from March 1		0	0	139	161	320	413	580	536	384	99	86	2	2720
Gross Pond Evap	Inch	2.71	2.75	4.49	4.09	5.8	5.54	6.4	5.94	4.54	2.41	1.83	0.99	47.49
Net Pond Evap	Inch	2.59	2.47	4.02	1.18	4.44	4.23	3.71	5.86	3.82	1.39	1.47	0.33	35.51
Longmont West	Avg. Temp ° F	33.45	36.99	42.19	46.05	57.95	62.21	68.1	68.67	63.52	43.29	41.34	24.39	49.01
Ref date as of 12/31/2009	Total Precip "	0.05	0.24	0.22	3.39	1.14	2.2	2.3	0.2	0.84	1.1	0.43	0.42	12.53
Site Type: Turf	Total Alfalfa ETr "	2.98	3.2	5.04	4.72	6.61	6.22	7.01	6.56	5.07	2.72	2.16	1.14	53.43
Total Growing Degee Days from March 1		0	0	139	162	319	394	552	559	449	140	143	12	2869
Gross Pond Evap	Inch	2.5	2.69	4.23	3.96	5.55	5.22	5.89	5.51	4.26	2.28	1.81	0.96	44.86
Net Pond Evap	Inch	2.47	2.52	4.08	1.59	4.75	3.68	4.28	5.37	3.67	1.51	1.51	0.66	36.09
Fort Lupton	Avg. Temp ° F	33.95	37.3	41.75	46.25	58.91	63.4	69.18	68.74	61.46	41.75	39.7	22.44	48.74
Ref date as of 12/31/2009	Total Precip "	0.02	0	0.3	1.96	2.12	2.81	3.21	0.17	0.85	0.89	0.18	0.22	12.73
Site Type: Turf	Total Alfalfa ETr "	3.75	3.99	6.02	5.39	7.68	7.22	8.43	8.51	6.33	3.53	3.3	1.64	65.79
Total Growing Degee Days from March 1		0	0	162	179	360	440	601	574	413	124	135	14	3002
Gross Pond Evap	Inch	3.15	3.35	5.06	4.53	6.45	6.06	7.08	7.15	5.32	2.97	2.77	1.38	55.27
Net Pond Evap	Inch	3.14	3.35	4.85	3.16	4.97	4.1	4.83	7.03	4.72	2.34	2.65	1.22	46.36
Boulder NW	Avg. Temp ° F	37.23	38.77	42.65	46.67	59.03	63.89	69.81	70.05	57.07	41.96	41.67	25.26	49.51
Ref date as of 12/31/2009	Total Precip "	0.39	0.28	0.58	4.17	2.03	1.61	2.34	0.22	0.4	1.94	0.54	0.59	15.09
Site Type: Turf	Total Alfalfa ETr "	3.64	3.52	5.32	4.9	6.85	6.64	7.53	7.49	5.45	3.08	2.72	1.75	58.89
Total Growing Degee Days from March 1		0	0	151	173	350	450	594	596	384	138	143	13	2992
Gross Pond Evap	Inch	3.06	2.96	4.47	4.12	5.75	5.58	6.33	6.29	4.58	2.59	2.28	1.47	49.48
Net Pond Evap	Inch	2.78	2.76	4.06	1.2	4.33	4.45	4.69	6.14	4.3	1.23	1.91	1.06	38.91
Boulder East	Avg. Temp ° F	37.71	39.1	43.65	47.3	59.93	64.29	70.42	70.76	63.21	43.01	41.67	25.18	50.52
Ref date as of 12/31/2009	Total Precip "	0.64	0.12	0.37	4.11	2.34	1.53	2.39	0.13	0.24	1.38	0.44	0.4	14.09
Site Type: Turf	Total Alfalfa ETr "	3.58	3.34	5.39	4.77	6.68	6.17	7.32	7.26	5.32	2.89	2.15	1.45	56.32
Total Growing Degee Days from March 1		0	0	153	163	342	432	599	599	424	133	125	15	2985
Gross Pond Evap	Inch	3.01	2.81	4.53	4.01	5.61	5.18	6.15	6.1	4.47	2.43	1.81	1.22	47.33
Net Pond Evap	Inch	2.56	2.72	4.27	1.13	3.97	4.11	4.48	6.01	4.3	1.46	1.5	0.94	37.45
Boulder Flatiron	Avg. Temp ° F	35.61	37.13	41.3	45.29	57.76	62.06	67.32	66.54	59.28	41.18	38.69	23.32	47.96
Ref date as of 12/31/2009	Total Precip "	0.17	0.1	0.34	4.59	3.84	2.2	2.81	0.43	0.39	1.75	0.47	0.25	17.34
Site Type: Turf	Total Alfalfa ETr "	2.83	2.82	4.46	3.88	5.22	4.58	4.99	5.04	3.67	2.14	1.78	1.28	42.69
Total Growing Degee Days from March 1		0	0	142	148	313	391	534	516	381	118	116	11	2670
Gross Pond Evap	Inch	2.38	2.37	3.75	3.26	4.38	3.85	4.19	4.23	3.08	1.8	1.5	1.08	35.87
Net Pond Evap	Inch	2.26	2.3	3.51	0.05	1.7	2.31	2.22	3.93	2.81	0.57	1.17	0.9	23.73
Boulder SW	Avg. Temp ° F	38.68	40.18	43.86	46.73	59.4	63.65	69.84	70.25	63.32	44.04	45.06	28.19	51.1
Ref date as of 12/31/2009	Total Precip "	0.33	0.22	0.67	5.34	2.46	3.27	1.5	0.34	0.43	2.01	0.51	0.3	17.38
Site Type: Turf	Total Alfalfa ETr "	4.41	3.77	5.69	4.71	6.44	5.88	6.8	6.87	5.57	3.27	2.91	2.12	58.44
Total Growing Degee Days from March 1		0	0	138	139	334	422	601	598	428	118	122	16	2916
Gross Pond Evap	Inch	3.7	3.17	4.78	3.96	5.41	4.94	5.71	5.77	4.68	2.75	2.44	1.78	49.09
Net Pond Evap	Inch	3.47	3.01	4.31	0.22	3.69	2.65	4.66	5.53	4.38	1.34	2.09	1.57	36.92
Greeley04	Avg. Temp ° F	#DIV/0!	#DIV/0!	#DIV/0!	#DIV/0!	#DIV/0!	62.77	68.83	66.8	59.48	40.16	34.97	17.61	50.09
Ref date as of 123109/0/2009	Total Precip "	0	0	0	0	0	3.44	1.89	2.65	0.75	0.63	0.2	0.01	9.57
Site Type: Fully irrigated	Total Alfalfa ETr "	0	0	0	0	0	6.73	8.4	7.95	6.26	3.38	2.4	0.86	35.98
Total Growing Degee Days from March 1		0	0	0	0	0	432	582	544	409	121	98	2	2188
Gross Pond Evap	Inch	0	0	0	0	0	5.65	7.06	6.68	5.26	2.84	2.02	0.72	30.23
Net Pond Evap	Inch	0	0	0	0	0	3.25	5.73	4.82	4.73	2.4	1.88	0.72	23.53