SCSB#000: Prediction Tables

Table 1. Overview of tools presented here for predicting impact of chemicals on groundwater quality.
Tool	Simplifications and Assumptions	Data Required

Maximum Groundwater Hazard	Assumes all applied chemical enters aquifer Ignores degradation in soil	Application rate Critical concentration- (HAL or MCL)
Retardation Factor	Ranks chemicals in relation to the speed at which they move or the amount of water needed to leach them to a specified depth Ignores degradation rate Ignores toxicity Ignores amount applied	Partition coefficient Henry's constant Soil field capacity Soil bulk density
Attenuation Factor	Ranks chemicals by the fraction of the applied amount which will leach to groundwater Ignores application amount Ignores toxicity	Partition Coefficient Field Capacity Bulk density Degradation rate Depth to groundwater
Groundwater Hazard Index as calculated with CMLS model	Estimates amount of chemical leaching to groundwater using CMLS model, mixes that chemical in the aquifer to estimate its concentration, and uses that value to calculate the groundwater hazard index	Application Rate Critical Concentration Partition Coefficient Degradation Rate Daily Infiltration Daily PET Field Capacity Wilting Point Bulk Density

Table 2. Maximum groundwater hazard values for selected herbicides used in cotton.
Common Name	Application Rate	C_Critical	GWH_Max	Minimum Residence Time	Critical Leaching Amount

	kg ha^-1	ppb		days	kg ha^-1
BENSULIDE	6.72	50	53.8	689.8	0.125
CYANAZINE	1.80	10	72.6	86.5	0.025
DCPA	11.76	4000	1.2	23.4	10.000
DIURON	1.79	10	71.7	554.7	0.025
EPTC	2.21	200	4.4	12.8	0.500
FENOXAPROP-ETHYL	0.17	20	3.3	15.6	0.050
FLUOMETURON	2.28	90	10.2	284.2	0.225
GLYPHOSATE AMINE SALT	1.68	700	1.0	0	1.750
LACTOFEN	0.22	10	8.8	9.4	0.025
METOLACHLOR	2.24	100	9.0	284.7	0.250
NORFLURAZON	2.21	300	3.0	46.8	0.750
OXYFLUORFEN	0.56	20	11.2	122.00	0.050
PARAQUAT DICHLORIDE SALT	1.12	30	14.9	3900.5	0.075
PENDIMETHALIN	2.24	300	3.0	142.1	0.750
PROMETRYN	2.69	30	35.8	309.8	0.075
SETHOXYDIM	0.42	600	0.3	0	1.500
TRIFLURALIN	2.24	5	179.0	449.0	0.012

Table 3. Retardation factors for selected herbicides.
Common Name	Koc (ml/g OC)	RF for Eufaula Soil OC = 0.0009 g/g r = 1.52 Mg/m³ J_FC= 0.091 m³/m³	RF for Teller Soil OC = 0.0038 g/g r = 1.74 Mg/m³ J_FC= 0.274 m³/m³	RF for Mclain Soil OC = 0.0079 g/g r = 1.52 Mg/m³ J_FC= 0.358 m³/m³

SETHOXYDIM	100	2.5	3.4	4.4
FLUOMETURON	100	2.5	3.4	4.4
CYANAZINE	190	3.9	5.6	7.4
METOLACHLOR	200	4.0	5.8	7.7
EPTC	200	4.0	5.8	7.7
PROMETRYN	400	7.0	10.6	14.4
DIURON	480	8.2	12.6	17.1
NORFLURAZON	700	11.5	17.9	24.5
BENSULIDE	1000	16.0	25.1	34.5
PENDIMETHALIN	5000	76.2	121.7	168.7
DCPA	5000	76.2	121.7	168.7
TRIFLURALIN	8000	121.3	194.0	269.3
FENOXAPROP-ETHYL	9490	143.7	230.0	319.3
LACTOFEN	10000	151.3	242.3	336.4
GLYPHOSATE AMINE SALT	24000	361.8	580.2	806.0
OXYFLUORFEN	100000	1504.3	2414.1	3355.2
PARAQUAT	1000000	15034.0	24132.4	33542.9

Table 4. Attenuation factors and rankings for selected herbicides.
Common Name	Half-life (days)	RF for Eufaula Soil	AF for Eufaula Soil	RF for McLain Soil	AF for McLain Soil	Rank
Common Name	Half-life (days)	RF for Eufaula Soil	AF for Eufaula Soil	RF for McLain Soil	AF for McLain Soil	RF	AF

FLUOMETURON	85	2.5	9.6E-01	4.4	7.8E-01	1	1
METOLACHLOR	90	4.0	9.4E-01	7.7	6.5E-01	4	2
DIURON	90	8.2	8.9E-01	17.1	3.9E-01	7	3
PROMETRYN	60	7.0	8.6E-01	14.4	3.0E-01	6	4
BENSULIDE	120	16.0	8.4E-01	34.5	2.4E-01	9	5
CYANAZINE	14	3.9	7.1E-01	7.4	7.3E-02	3	6
NORFLURAZON	30	11.5	6.2E-01	24.5	1.7E-02	8	7
SETHOXYDIM	5	2.5	5.3E-01	4.4	1.3E-02	1	8
EPTC	6	4.0	4.3E-01	7.7	1.7E-03	4	9
DCPA	100	76.2	3.8E-01	168.7	2.3E-04	10	10
PENDIMETHALIN	90	76.2	3.4E-01	168.7	9.1E-05	10	11
GLYPHOSATE	47	361.8	6.1E-05	806.0	1.1E-37	15	13
PARAQUAT	1000	15034.0	5.8E-09	33542.9	5.2E-73	17	14
FENOXAPROP-ETHYL	9	143.7	1.8E-09	319.3	3.5E-77	13	15
OXYFLUORFEN	35	1504.3	2.9E-24	3355.2	2.7E-207	16	16
LACTOFEN	3	151.3	2.3E-28	336.4	2.2E-242	14	17
TRIFLURALIN	60	121.3	7.8E-02	269.3	2.1E-10	12	12

Table 5. Summary list of factors influencing chemical leaching and the way they are addressed in calculation of groundwater hazard with the CMLS model.
Estimating amount leached	GWH using CMLS
Amount chemical applied	Entered by user
Biological degradation	First-order degradation in root zone
Chemical transformation	Ignored unless it can be incorporated into first-order degradation rate above
Chemical taken up by plants	Ignored, assumed zero
Chemical lost to atmosphere	Ignored, assumed zero
Chemical lost to runoff	Ignored, assumed zero
Amount of water passing through soil	Daily water balance model
Water infiltration/runoff	SCS curve number approach
Water storage	Estimated using field capacity and permanent wilting point
Rainfall distribution and irrigation practices	Historical weather, weather generator and irrigation are supported
Plant uptake of water	Built-in evapotranspiration estimators or historical data
Root depth	Assumed constant over time
Sorption of chemical	Assumed linearly related to concentration in water Assumed to be reversible Assumed to be instantaneous

Mixing and Dilution
Initial concentration in aquifer	Assumed to be zero
Fraction of recharge by percolation	Assumed to be 100%
Vertical Mixing	Mixes in saturated aquifer to user-defined depth
Lateral mixing	Ignored
Dispersion in unsaturated zone	Ignored

Critical Concentration	User input; USEPA lifetime health advisory level or its equivalent suggested

Uncertainty and Variability
Unknown future weather	Built-in Monte Carlo simulation using many weather records for the site to obtain distributions of GWH
Spatial variability	Ability to simulate many profiles and combine them to obtain distribution of GWH

Table 6. Summary of travel time to 0.5 m, groundwater hazard estimates, and probability of exceeding GWH=1.0 (POE) for different soils using the CMLS model with weather from Caddo County, Oklahoma and supplemental irrigation of 25 mm/week during the summer growing season. Statistics and probabilities are based on 50 equally likely weather realizations for the site.
	Mclain Soil		Teller Soil		Eufaula Soil Site#1		Eufaula Soil Site#2		Eufaula Soil Site#3
	Travel Time (days)	GWH	Travel Time (days)	GWH	Travel Time (days)	GWH	Travel Time (days)	GWH	Travel Time (days)	GWH

Bensulide
Minimum	2686	1.3E-07	1162	0.001	94	5.0	397	0.6	137	4.3
Maximum	3433	9.8E-06	1849	0.065	410	31.0	782	5.4	438	24.0
Mean	3187	1.1E-06	1407	0.023	200	19.0	493	3.4	329	9.3
Std. Dev.	198	1.9E-06	160	0.020	97	7.7	87	1.0	91	5.8
POE		0.0		0.0		1.0		0.90		1.0
Cyanazine
Minimum	431	3.5E-17	108	2.0E-8	21	2.1	52	0.6	29	2.0
Maximum	852	3.9E-08	445	3.5E-1	72	26.0	98	5.5	73	17.0
Mean	624	2.6E-09	252	3.7E-2	49	7.6	73	2.4	53	5.9
Std. Dev.	137	6.7E-09	112	6.5E-2	12	5.2	13	1.5	10	3.2
POE		0.0		0.0		1.0		0.74		1.0
Diuron
Minimum	1197	3.7E-05	446	0.01	55	30.0	94	3.1	68	28.0
Maximum	1878	7.1E-03	868	2.30	115	47.0	407	35.0	122	42.0
Mean	1527	9.2E-04	672	0.68	86	37.0	173	21.0	97	34.0
Std. Dev.	129	1.3E-03	134	0.66	16	4.7	78	8.1	14	3.8
POE		0.0		0.29		1.0		1.0		1.0
Fluometuron
Minimum	137	0.19	72	3.4	8	6.3	29	5.7	8	6.3
Maximum	490	3.30	136	5.7	59	9.6	72	8.1	59	9.6
Mean	365	0.73	106	4.4	38	7.5	51	6.7	39	7.4
Std. Dev.	92	0.77	18	0.6	13	0.8	10	0.6	13	0.8
POE		0.16		1.0		1.0		1.0		1.0
Metolachlor
Minimum	438	0.01	115	0.3	25	5.2	52	4.1	29	5.1
Maximum	866	0.31	459	3.7	72	7.4	101	6.0	73	7.2
Mean	651	0.10	284	1.4	50	6.1	76	5.0	55	5.9
Std. Dev.	133	0.09	108	1.1	11	0.5	13	0.5	10	0.4
POE		0.0		0.47		1.0		1.0		1.0
Prometryn
Minimum	1041	4.8E-07	417	0.002	52	11.0	80	4.6	59	10.0
Maximum	1569	2.1E-04	831	0.290	101	20.0	177	14.0	108	18.0
Mean	1265	3.4E-05	538	0.120	78	15.0	125	8.6	85	14.0
Std. Dev.	132	3.6E-05	118	0.076	15	2.5	20	1.9	14	2.2
POE		0.0		0.0		1.0		1.0		1.0
Sethoxydim
Minimum	137	0.0	72	1.9E-9	8	8.4E-5	29	1.4E-5	8	8.4E-5
Maximum	490	1.7E-09	136	1.4E-5	59	9.9E-2	72	5.4E-3	59	9.9E-2
Mean	365	3.7E-11	106	1.3E-6	38	7.6E-3	51	6.7E-4	39	6.7E-3
Std. Dev.	92	2.4E-10	18	2.8E-6	13	1.6E-2	10	1.2E-3	13	1.6E-2
POE		0.0		0.0		0.0		0.0		0.0

Table 7. Input data needed for the soils in Fish watershed that are needed to run the model SIMPLE.

Soil series Texture K
Factor Slope
Length Initial
Soil P pH Clay Bulk
Density Organic
Carbon Hydrologic
Group Curve
Number

ft mg kg^-1 % (g cm^-3) %

Allegheny
Baxter
Captina
Clarksville
Elsah
Enders
Enders-Allegheny
Guin
Hector-Mountainburg
Johnsburg*
Nixa
Pickwick
Razor
Savannah
gravelly loam
cherty silt loam
silt loam
cherty silt loam
cherty silt loam
stony loam
stony loam
cherty silt loam
stony fine sandy loam
silt loam
cherty silt loam
silt loam
silt loam
fine sandy loam
0.32
0.37
0.43
0.37
0.37
0.37
0.37
0.37
0.28
0.43
0.43
0.43
0.37
0.24
300
50
400
50
50
300
100
50
100
400
300
300
50
500
45
36
115
86
25
193
75
25
26
89
119
115
100
89
5
5.5
5.5
4.8
6.05
4.55
4.55
4.8
5.8
5
5
5
6.7
4.55
11.5
19.5
14
20
14
17.5
17.5
20
12.5
17.5
18.5
17
17.5
9.5
1.4
1.3
1.35
1.3
1.4
1.375
1.375
1.3
1.45
1.35
1.4
1.4
1.475
1.55
0.73
1.16
1.16
0.73
0.74
1.74
1.74
0.73
0.73
1.16
1.16
1.02
1.16
1.02
B
B
C
B
B
C
C-B
B
D-D
D
C
B
B
C
69
60
79
69
69
79
79-69
69
84-84
84
79
69
69
79

Table 8. Spatial characteristics of the Fish watershed.
Characteristic

Area (ha)		2,248
Elevation range (m)		306-439
Slope range (deg)		1-34
Landuse category (%)
	pasture	19.8
	forest	79.3
	shrub & brush	0.9
	poultry houses	0.2
	surface water	0.3
	utilities	0.4
Dominant soils (%)
	Captina	3.1
	Eisah	6.0
	Clarksville	43.1
	Nixa	29.2
	Razort	10.8

Table 9. Extent of simulated P loadings from the Fish watershed.
Form of P	Loading rate	Fish watershed

	kg P/ha yr	ha	%
Runoff	< 2	1,926	81.23
	2.0 - 3.0	298	13.26
	3.0 - 4.0	104	4.63
	> 4.0	20	0.88
Sediment	< 0.033	2,061	91.68
	0.034 - 0.067	126	5.62
	0.068 - 1.333	40	1.80
	1.334 - 2.0	15	0.65
	> 2.0	6	0.25
Total	< 2.0	1,813	80.64
	2.0 - 3. 0	236	10.51
	3.0 - 4.0	142	6.32
	4.0 - 5.0	47	2.11
	> 5.0	10	0.42

Table 7. Input data needed for the soils in Fish watershed that are needed to run the model SIMPLE.
Soil series	Texture	K Factor	Slope Length	Initial Soil P	pH	Clay	Bulk Density	Organic Carbon	Hydrologic Group	Curve Number

			ft	mg kg^-1		%	(g cm^-3)	%
Allegheny Baxter Captina Clarksville Elsah Enders Enders-Allegheny Guin Hector-Mountainburg Johnsburg* Nixa Pickwick Razor Savannah	gravelly loam cherty silt loam silt loam cherty silt loam cherty silt loam stony loam stony loam cherty silt loam stony fine sandy loam silt loam cherty silt loam silt loam silt loam fine sandy loam	0.32 0.37 0.43 0.37 0.37 0.37 0.37 0.37 0.28 0.43 0.43 0.43 0.37 0.24	300 50 400 50 50 300 100 50 100 400 300 300 50 500	45 36 115 86 25 193 75 25 26 89 119 115 100 89	5 5.5 5.5 4.8 6.05 4.55 4.55 4.8 5.8 5 5 5 6.7 4.55	11.5 19.5 14 20 14 17.5 17.5 20 12.5 17.5 18.5 17 17.5 9.5	1.4 1.3 1.35 1.3 1.4 1.375 1.375 1.3 1.45 1.35 1.4 1.4 1.475 1.55	0.73 1.16 1.16 0.73 0.74 1.74 1.74 0.73 0.73 1.16 1.16 1.02 1.16 1.02	B B C B B C C-B B D-D D C B B C	69 60 79 69 69 79 79-69 69 84-84 84 79 69 69 79