Pond Evaporation Calculation													5/19/12
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	2011	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	or Avg.
Ovid	Avg. Temp ° F	24.51	24.43	38.28	46.5	54.53	69.24	77.91	74.41	60.9	50.94	36.5	27.09	48.77
Ref date as of 12/31/2011	Total Precip "	0.29	0.58	0.94	2.17	4.29	2.35	3.75	4.22	1.32	1.14	0.74	0.08	21.87
Site Type: Alfalfa	Total Alfalfa ETr "	2.28	2.88	4.16	5.52	7.02	10.16	10.14	8.23	5.88	5.02	4.3	2.84	68.43
Total Growing Degee Days from March 1		0	0	105	168	271	542	767	705	426	300	116	29	3429
Gross Pond Evap	Total "	1.92	2.42	3.49	4.64	5.9	8.53	8.52	6.91	4.94	4.22	3.61	2.39	57.49
Net Pond Evap	Total "	1.71	2.01	2.84	3.12	2.89	6.89	5.89	3.96	4.02	3.42	3.09	2.33	42.17
Crook	Avg. Temp ° F	24.95	25.2	39.49	45.85	53.14	67.64	75.93	73.15	60.05	48.76	35.26	25.42	47.9
Ref date as of 12/31/2011	Total Precip "	0.18	0.58	1.21	1.72	5.44	2.39	2.83	1.67	1.6	1.19	0.46	0.21	19.48
Site Type: Alfalfa	Total Alfalfa ETr "	2.27	2.97	4.51	5.51	6.77	9.16	9.5	8.19	5.89	4.66	4.18	2.88	66.49
Total Growing Degee Days from March 1		0	0	125	165	261	506	720	671	418	276	104	31	3277
Gross Pond Evap	Inch	1.91	2.49	3.79	4.63	5.69	7.69	7.98	6.88	4.95	3.91	3.51	2.42	55.85
Net Pond Evap	Inch	1.78	2.09	2.94	3.42	1.88	6.02	6	5.71	3.83	3.08	3.19	2.27	42.21
Sterling	Avg. Temp ° F	24.16	25.78	40.43	46.39	53.29	68.44	76	74.08	61.02	49.21	35.03	25.51	48.28
Ref date as of 12/31/2011	Total Precip "	0.32	0.28	0.77	1.87	6.35	1.88	4.79	3.21	1.24	1.35	0.27	0.23	22.56
Site Type: Alfalfa	Total Alfalfa ETr "	1.96	3.04	4.9	5.86	6.63	9.76	9.82	8.72	6.14	4.98	3.84	2.31	67.96
Total Growing Degee Days from March 1		0	0	140	184	261	525	724	692	432	290	111	25	3384
Gross Pond Evap	Inch	1.65	2.55	4.12	4.92	5.57	8.2	8.25	7.32	5.16	4.18	3.23	1.94	57.09
Net Pond Evap	Inch	1.42	2.36	3.58	3.61	1.12	6.88	4.9	5.08	4.29	3.24	3.04	1.78	41.3
Brush	Avg. Temp ° F	23.02	25.98	42.34	47.98	54.3	68.76	75.65	74.59	61.45	49.44	35.09	25.01	48.63
Ref date as of 12/31/2011	Total Precip "	0.42	0.17	0.31	1.36	4.76	0.97	3.91	1.31	1.41	1.73	0.28	0.21	16.84
Site Type: Alfalfa	Total Alfalfa ETr "	1.92	2.93	5.78	6.63	6.49	10.17	9.73	8.35	5.72	4.78	3.59	2.16	68.25
Total Growing Degee Days from March 1		0	0	166	199	273	535	724	696	429	280	107	17	3426
Gross Pond Evap	Inch	1.61	2.46	4.86	5.57	5.45	8.54	8.17	7.01	4.8	4.02	3.02	1.81	57.32
Net Pond Evap	Inch	1.32	2.34	4.64	4.62	2.12	7.86	5.44	6.1	3.82	2.8	2.82	1.67	45.55
Fort Morgan	Avg. Temp ° F	24.69	26.96	40.98	46.36	53.07	67.68	74.57	73.54	60.49	48.15	34.22	23.51	47.85
Ref date as of 12/31/2011	Total Precip "	0.63	0.43	0.43	1.58	6.62	1.73	4.3	0.53	1.28	2.11	0.75	0.35	20.74
Site Type: Turf	Total Alfalfa ETr "	1.87	2.67	4.47	5.58	6.02	8.39	8.84	7.95	5.11	3.87	2.96	1.85	59.58
Total Growing Degee Days from March 1		0	0	148	178	261	514	702	674	422	265	93	16	3273
Gross Pond Evap	Inch	1.57	2.24	3.75	4.69	5.06	7.05	7.43	6.68	4.29	3.25	2.49	1.55	50.05
Net Pond Evap	Inch	1.13	1.94	3.45	3.58	0.42	5.84	4.42	6.31	3.4	1.77	1.96	1.31	35.53
Wiggins	Avg. Temp ° F	23.6	25.97	41.35	46.79	53.55	68.25	74.27	73.66	60.87	48.5	34.68	23.09	47.88
Ref date as of 12/31/2011	Total Precip "	0.19	0.23	0.3	1.12	3.27	1.14	4.89	1.85	0.7	1.85	0.14	0.12	15.8
Site Type: Alfalfa	Total Alfalfa ETr "	2.18	3.14	5.62	6.54	6.97	10.12	9.13	8.61	6.04	4.76	3.51	1.92	68.54
Total Growing Degee Days from March 1		0	0	162	192	265	522	699	680	431	266	102	18	3337
Gross Pond Evap	Inch	1.83	2.64	4.72	5.49	5.85	8.5	7.67	7.23	5.07	4	2.95	1.61	57.56
Net Pond Evap	Inch	1.7	2.48	4.51	4.71	3.57	7.7	4.25	5.94	4.58	2.7	2.85	1.53	46.52
Fort Collins East	Avg. Temp ° F	26.62	26.2	42.23	46.99	52.52	66.58	72.63	71.36	59.94	48.66	36.18	25.16	47.92
Ref date as of 12/31/2011	Total Precip "	0.18	0.49	0.16	1.59	3.73	2.08	2.05	0.52	1.33	1.92	0.34	0.39	14.78
Site Type: Alfalfa	Total Alfalfa ETr "	2.54	3.19	5.44	6.32	6.36	8.89	8.45	8.05	5.67	4.59	3.62	2.18	65.3
Total Growing Degee Days from March 1		0	0	140	177	236	486	668	628	398	269	76	18	3096
Gross Pond Evap	Inch	2.13	2.68	4.57	5.31	5.34	7.47	7.1	6.76	4.76	3.86	3.04	1.83	54.85
Net Pond Evap	Inch	2.01	2.34	4.46	4.2	2.73	6.01	5.66	6.4	3.83	2.51	2.8	1.56	44.51
Eaton	Avg. Temp ° F	26.1	26.21	41.5	46.8	52.56	66.94	73.16	72.23	60.84	49.08	35.61	25.23	48.02
Ref date as of 12/31/2011	Total Precip "	0.14	0.36	0.38	1.31	5.1	0.95	1.55	0.37	0.75	2.16	0.46	0.16	13.69
Site Type: Alfalfa	Total Alfalfa ETr "	2.28	3.25	5.49	6.6	6.46	9.53	8.87	8.13	5.82	4.5	3.56	1.99	66.48
Total Growing Degee Days from March 1		0	0	145	185	243	495	684	648	415	272	87	21	3195
Gross Pond Evap	Inch	1.92	2.73	4.61	5.54	5.43	8.01	7.45	6.83	4.89	3.78	2.99	1.67	55.85
Net Pond Evap	Inch	1.82	2.48	4.35	4.63	1.86	7.34	6.37	6.57	4.36	2.27	2.67	1.56	46.28
Johnsons Corner	Avg. Temp ° F	27.57	28.11	42.81	47.06	52.62	66.91	73.73	73.04	61.8	50.64	37.48	24.89	48.89
Ref date as of 12/31/2011	Total Precip "	0.33	0.51	0.26	2.04	4.65	0.78	1.15	0.63	0.77	1.26	0.62	0.69	13.69
Site Type: Alfalfa	Total Alfalfa ETr "	2.23	2.94	5.33	6.15	6.1	8.79	8.79	8.3	5.68	4.77	3.39	1.61	64.08
Total Growing Degee Days from March 1		0	0	141	175	231	498	693	663	414	269	74	9	3167
Gross Pond Evap	Inch	1.87	2.47	4.48	5.17	5.12	7.38	7.38	6.97	4.77	4.01	2.85	1.35	53.82
Net Pond Evap	Inch	1.64	2.11	4.3	3.74	1.87	6.84	6.58	6.53	4.23	3.12	2.41	0.87	44.24
Gilcrest	Avg. Temp ° F	23.73	25.71	41.64	46.68	52.19	67.13	73.37	73.03	60.84	48.96	35.44	20.26	47.42
Ref date as of 12/31/2011	Total Precip "	0.21	0.3	0.08	1.38	4.47	0.58	1.62	1.07	0.45	1.7	0.58	0.43	12.87
Site Type: Alfalfa	Total Alfalfa ETr "	1.92	2.88	5.36	6.22	6.01	9.46	8.69	8.09	5.09	4.12	3.13	1.39	62.36
Total Growing Degee Days from March 1		0	0	150	179	228	508	681	668	425	274	91	8	3212
Gross Pond Evap	Inch	1.61	2.42	4.5	5.22	5.05	7.95	7.3	6.8	4.28	3.46	2.63	1.17	52.39
Net Pond Evap	Inch	1.47	2.21	4.45	4.26	1.92	7.54	6.17	6.05	3.96	2.27	2.22	0.87	43.39
Longmont South	Avg. Temp ° F	29.73	29.39	43.82	48.16	53.42	67.97	73.91	74.16	62.43	51.33	39.46	25.92	49.98
Ref date as of 12/31/2011	Total Precip "	0.35	0.54	0.25	1.94	4.05	0.83	2.33	0.4	1.53	1.41	0.46	0.79	14.88
Site Type: Alfalfa	Total Alfalfa ETr "	2.65	3.21	5.8	6.47	6.57	9.31	8.35	8.85	5.5	4.93	4	1.96	67.6
Total Growing Degee Days from March 1		0	0	154	182	237	505	694	675	419	287	95	17	3265
Gross Pond Evap	Inch	2.23	2.7	4.87	5.43	5.52	7.82	7.01	7.43	4.62	4.14	3.36	1.65	56.78
Net Pond Evap	Inch	1.98	2.32	4.7	4.08	2.68	7.24	5.38	7.15	3.55	3.15	3.04	1.09	46.36
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 12/31/2010	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	27.99	27.41	42.32	46.53	52.05	66.2	73.24	72.47	60.22	49.09	37.13	26.21	48.41
Ref date as of 12/31/2011	Total Precip "	0.32	0.41	0.32	2.11	4.31	2.41	1.56	0.27	2.22	1.48	0.52	0.69	16.62
Site Type: Turf	Total Alfalfa ETr "	1.69	2.17	4.37	5.39	5.24	7.71	7.47	7.08	4.93	3.67	2.42	1.33	53.47
Total Growing Degee Days from March 1		0	0	127	154	219	477	673	641	402	271	85	23	3072
Gross Pond Evap	Inch	1.42	1.82	3.67	4.53	4.4	6.48	6.27	5.95	4.14	3.08	2.03	1.12	44.91
Net Pond Evap	Inch	1.2	1.54	3.45	3.05	1.38	4.79	5.18	5.76	2.59	2.05	1.67	0.63	33.29
Windsor	Avg. Temp ° F	-63.55	28.01	43.17	47.61	53.39	68.08	74.83	74.8	63.2	51.2	37.71	26.01	51.64
Ref date as of 12/31/2011	Total Precip "	0.05	0.52	0.18	1.85	5.21	1.05	3.18	0.12	1.16	1.74	0.72	0.51	16.29
Site Type: Dryland Pasture	Total Alfalfa ETr "	0.76	2.62	5.12	5.98	5.1	6.19	8.85	8.69	5.61	4.41	2.74	1.26	57.33
Total Growing Degee Days from March 1		0	0	149	193	253	522	723	700	437	287	83	9	3356
Gross Pond Evap	Inch	0.64	2.2	4.3	5.02	4.28	5.2	7.43	7.3	4.71	3.7	2.3	1.06	48.14
Net Pond Evap	Inch	0.6	1.84	4.17	3.73	0.64	4.46	5.21	7.22	3.9	2.49	1.8	0.7	36.76
Greeley West	Avg. Temp ° F	25.67	26.52	41.78	46.62	52.58	67.31	74.24	73.45	61.37	49.43	35.17	23.44	48.13
Ref date as of 12/31/2011	Total Precip "	0	0	0	0	0	0	0	0	0	0.99	0.74	0.58	2.31
Site Type: Turf	Total Alfalfa ETr "	1.68	2.44	4.74	5.77	5.78	8.79	8.88	7.73	5.4	3.96	2.48	1.23	58.88
Total Growing Degee Days from March 1		0	0	136	172	239	506	703	672	419	286	70	8	3211
Gross Pond Evap	Inch	1.41	2.05	3.98	4.85	4.86	7.38	7.46	6.49	4.54	3.33	2.08	1.03	49.46
Net Pond Evap	Inch	1.41	2.05	3.98	4.85	4.86	7.38	7.46	6.49	4.54	2.63	1.57	0.63	47.85
Loveland	Avg. Temp ° F	27.6	28.15	43.14	46.99	52.87	67.32	74.58	73.93	61.68	50.37	37.95	25.35	49.16
Ref date as of 12/31/2011	Total Precip "	0.46	0.53	0.29	2.1	4.01	1.63	1.79	0.2	1.77	0.97	0.31	0.31	14.37
Site Type: Turf	Total Alfalfa ETr "	1.62	2.31	4.54	5.38	5.44	8.1	7.83	7.26	4.84	3.64	2.5	1.25	54.71
Total Growing Degee Days from March 1		0	0	141	170	235	509	706	687	433	294	86	16	3277
Gross Pond Evap	Inch	1.36	1.94	3.81	4.52	4.57	6.8	6.58	6.1	4.07	3.06	2.1	1.05	45.96
Net Pond Evap	Inch	1.04	1.57	3.61	3.05	1.76	5.66	5.32	5.96	2.83	2.38	1.88	0.83	35.89
Berthoud	Avg. Temp ° F	27.13	27.56	42.52	46.94	52.36	67.37	73.9	73.39	62.17	50.64	37.66	25.83	48.96
Ref date as of 12/31/2011	Total Precip "	0.31	0.79	0.15	2.22	4.46	0.85	1.5	1.34	0.87	1.54	0.54	0.65	15.22
Site Type: Turf	Total Alfalfa ETr "	1.86	2.69	4.93	5.77	5.73	8.72	8.52	7.74	5.35	4.34	2.96	1.47	60.08
Total Growing Degee Days from March 1		0	0	125	165	218	502	698	681	409	261	67	13	3139
Gross Pond Evap	Inch	1.56	2.26	4.14	4.85	4.81	7.32	7.16	6.5	4.49	3.65	2.49	1.23	50.46
Net Pond Evap	Inch	1.35	1.71	4.04	3.29	1.69	6.73	6.11	5.56	3.89	2.57	2.11	0.78	39.83
Longmont West	Avg. Temp ° F	29.72	30.13	44.87	49.01	54.55	69.84	76.39	75.83	63.52	52.19	40.69	28	51.23
Ref date as of 12/31/2011	Total Precip "	0.32	0.51	0.15	1.99	3.93	0.72	0.9	0.07	1.12	1.26	0.33	0.32	11.62
Site Type: Turf	Total Alfalfa ETr "	1.67	2.39	4.64	5.45	5.51	8.04	7.95	7.15	4.56	3.64	2.63	1.31	54.94
Total Growing Degee Days from March 1		0	0	145	182	248	551	741	721	432	287	105	29	3441
Gross Pond Evap	Inch	1.4	2.01	3.9	4.58	4.63	6.75	6.68	6.01	3.83	3.06	2.21	1.1	46.16
Net Pond Evap	Inch	1.18	1.65	3.79	3.19	1.88	6.25	6.05	5.96	3.05	2.18	1.98	0.88	38.04
Fort Lupton	Avg. Temp ° F	28.65	29.67	43.74	48.02	53.65	68.17	74.47	74.45	62.71	51.07	38.64	24.7	49.83
Ref date as of 12/31/2011	Total Precip "	0	0	0	0	0	0	0	0	0	0	0	0.28	0.28
Site Type: Turf	Total Alfalfa ETr "	2.1	2.98	5.19	5.86	6.07	9.67	9.53	8.96	5.87	4.65	3.63	1.75	66.26
Total Growing Degee Days from March 1		0	0	157	185	242	518	717	689	428	276	98	16	3326
Gross Pond Evap	Inch	1.76	2.5	4.36	4.92	5.1	8.12	8.01	7.53	4.93	3.91	3.05	1.47	55.66
Net Pond Evap	Inch	1.76	2.5	4.36	4.92	5.1	8.12	8.01	7.53	4.93	3.91	3.05	1.27	55.46
Boulder NW	Avg. Temp ° F	32.67	30.23	43.82	47.31	52.76	68.19	75.15	75.56	62.96	51.84	40.99	28.64	50.84
Ref date as of 12/31/2011	Total Precip "	0.28	0.58	0.43	2.06	4.7	0.95	1.33	0.33	2.02	1.29	0.4	0.78	15.15
Site Type: Turf	Total Alfalfa ETr "	2.47	2.51	4.81	5.3	5.56	7.96	7.51	7.48	4.9	4.08	3.16	1.63	57.37
Total Growing Degee Days from March 1		0	0	145	175	242	523	704	697	440	286	95	29	3336
Gross Pond Evap	Inch	2.07	2.11	4.04	4.45	4.67	6.69	6.31	6.28	4.12	3.43	2.65	1.37	48.19
Net Pond Evap	Inch	1.88	1.7	3.74	3.01	1.38	6.02	5.38	6.05	2.7	2.52	2.37	0.82	37.57
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	33.87	31.39	44.52	47.9	52.92	67.88	74.08	75.33	63.18	53.27	42.85	31.15	51.53
Ref date as of 12/31/2011	Total Precip "	0.16	0.18	0.32	1.85	4.41	1.01	3.02	0.62	2.69	1.09	0.57	0.67	16.59
Site Type: Turf	Total Alfalfa ETr "	3.04	2.77	5.01	5.73	5.79	8.31	8.07	8.1	5.1	4.38	3.53	1.91	61.74
Total Growing Degee Days from March 1		0	0	121	145	207	502	692	681	385	259	89	27	3108
Gross Pond Evap	Inch	2.55	2.33	4.21	4.81	4.86	6.98	6.78	6.8	4.28	3.68	2.97	1.6	51.85
Net Pond Evap	Inch	2.44	2.2	3.98	3.52	1.78	6.27	4.66	6.37	2.4	2.92	2.57	1.14	40.25