Stormwater runoff coefficients/curve numbers for different land uses

Curve numbers for urban and agricultural areas

The following tables were adapted from USDA Urban Hydrology for Small Watersheds - TR-55.

Curve numbers for urban and agricultural areas. Source: [USDA Urban Hydrology for Small Watersheds - TR-55. USDA Urban Hydrology for Small Watersheds - TR-55].
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Cover type and hydrologic condition	Soil Group A	Soil Group B	Soil Group C	Soil Group D
Open space poor condition (<50% cover)	68	79	86	89
Open space average condition (50-75% cover)	49	69	79	84
Open space good condition (>75% cover)	39	61	74	80
Impervious surfaces	98	98	98	98
Commercial (85% impervious)	89	92	94	95
Industrial (72% impervious)	81	88	91	93
Residential (65% impervious)	77	85	90	92
Residential (30% impervious)	57	72	81	86
Residential (12% impervious)	46	65	77	82
Pervious, no vegetation (newly graded)	77	86	91	94
Fallow with residue cover	74-76	83-85	88-90	90-93
Row crop, no residue	67-72	78-81	85-88	89-91
Row crop with residue	64-71	75-80	82-87	85-90
Pasture, good condition	39	61	74	80
Pasture, poor condition	68	79	86	89
Meadow	30	58	71	78
Woods, good condition	32	58	72	79
Woods, poor condition	57	73	82	86

Curve numbers for antecedent moisture condition II (Source USDA-NRCS).
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Land use description	Hydrologic soil group
	A	B	C	D
Meadow - good condition	30	58	72	78
Forest
Poor	45	66	77	83
Fair	36	60	73	79
Good	30	55	70	77
Open space
Poor	68	79	86	89
Fair	49	69	79	84
Good	39	61	74	80
Commercial 85% impervious	89	92	94	95
Industrial 72% impervious	81	88	91	93
Residential
1/8 acre lots (65% impervious)	77	85	90	92
1/4 acre lots (38% impervious)	61	75	83	87
1/2 acre lots (25% impervious)	54	70	80	85
1 acre lots (20% impervious)	51	68	79	84
Impervious areas	98	98	98	98
Roads (including right of way)
Paved	83	89	92	93
Gravel	76	85	89	91
Dirt	72	82	87	89
Row crops
Straight row - good	67	78	85	89
Contoured row - good	65	75	82	86
Pasture - good	39	61	74	80
Open water	99	99	99	99

Runoff coefficients for different soil groups and slopes

The following table was adapted from Hydrologic Analysis and Design (4th Edition) (McCuen, 2017).

Runoff coefficients for different soil groups and slopes. Coefficients are for recurrence intervals less than 25 years. Source: Hydrologic Analysis and Design (4th Edition) (McCuen, 2017).
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Land use	Soil Group A			Soil Group B			Soil Group C			Soil Group D
	0-2%	2-6%	>6%	0-2%	2-6%	>6%	0-2%	2-6%	>6%	0-2%	2-6%	>6%
Residential (65% impervious)	0.25	0.28	0.31	0.27	0.30	0.35	0.30	0.33	0.38	0.33	0.36	0.42
Residential (30% impervious)	0.19	0.23	0.26	0.22	0.26	0.30	0.25	0.29	0.34	0.28	0.32	0.39
Residential (12% impervious)	0.14	0.19	0.22	0.17	0.21	0.26	0.20	0.25	0.31	0.24	0.29	0.35
Commercial	0.71	0.71	0.72	0.71	0.72	0.72	0.72	0.72	0.72	0.72	0.72	0.72
Industrial	0.67	0.68	0.68	0.68	0.68	0.69	0.68	0.69	0.69	0.69	0.69	0.70
Streets	0.70	0.71	0.72	0.71	0.72	0.74	0.72	0.73	0.76	0.73	0.75	0.78
Parking	0.85	0.86	0.87	0.85	0.86	0.87	0.85	0.86	0.87	0.85	0.86	0.87
Open space	0.05	0.10	0.14	0.08	0.13	0.19	0.12	0.17	0.24	0.16	0.21	0.28
Cultivated land	0.08	0.13	0.16	0.11	0.15	0.21	0.14	0.19	0.26	0.18	0.23	0.31
Pasture	0.12	0.20	0.30	0.18	0.28	0.37	0.24	0.34	0.44	0.30	0.40	0.50
Meadow	0.10	0.16	0.25	0.14	0.22	0.30	0.20	0.28	0.36	0.24	0.30	0.40
Forest	0.05	0.08	0.11	0.08	0.11	0.14	0.10	0.13	0.16	0.12	0.16	0.20

Other sources of information for curve numbers

• MPCA MIDS memo: Regional Hydrologic Metrics – Curve Numbers
• Hydrology Training Series, Module 104, Runoff Curve Number Computations
• SCS Curve Number Method
• Basic Hydrology – Runoff Curve Numbers
• HydroCAD Curve Number
• TR-55 Curve Number Tables

Other sources of information on runoff coefficients

• Runoff coefficient fact sheet
• Rational Method Runoff Coefficient Tables for Storm Water Runoff Calculation
• Computing Stormwater Runoff Rates and Volumes
• Estimating Storm Water Runoff
• Hydrology Training Series Module 206 D - Peak Discharge
• Hydraulic Design Manual - Section 12: Rational Method
• Rational Equation Calculator