NRCS Curve Numbers (CN)

Land Use Description	Hydrologic Soil Group
Residential	A	B	C	D
Average Lot Size
1/8 acre or less	77	85	90	92
1/4 acre	61	75	83	87
1/3 acre	57	72	81	86
1/2 acre	54	70	80	85
1 acre	51	68	79	84
2 acre	46	65	77	82

Paved parking, roofs	98	98	98	98

Streets and Roads
Paved with curbs	98	98	98	98
Gravel	76	85	89	91
Dirt	72	82	87	89

Commercial and business areas	89	92	94	95

Industrial districts	81	88	91	93

Open spaces, lawns, parks
good condition	39	61	74	80
fair condition	49	69	79	84

Fallow	77	86	91	94
Row Crops	72	81	88	91
Source: Soil Conservation Service TR-55