---
title: "Curve Numbers"
canonical: "https://help.innovyze.com/space/xps/19661282/Curve%20Numbers"
format: markdown
---
The following table presents suggested Curves Numbers for use with SCS hydrology. For additional information, see Urban Hydrology for Small Watersheds, Technical Release 55, United States Department of Agriculture, June 1986


| **Land Use** | **Percent Impervious** | **Hydrologic Soil Group** |
| --- | --- | --- |
| **A** | **B** | **C** | **D** |
| **Urban Areas** |  |  |  |  |  |
| Parking lots, roofs, driveways and streets | 100 | 98 | 98 | 98 | 98 |
| Commercial development | 85 | 89 | 92 | 94 | 95 |
| Industrial development | 72 | 81 | 88 | 91 | 93 |
| Residential development |  |  |  |  |  |
| 1/8 acre lots or less | 65 | 77 | 85 | 90 | 92 |
| 1/4 acre lots | 38 | 61 | 75 | 83 | 87 |
| 1/3 acre lots | 30 | 57 | 72 | 81 | 86 |
| 1/2 acre lots | 25 | 57 | 70 | 80 | 85 |
| 1 acre lots | 20 | 51 | 68 | 79 | 84 |
| **Pervious Areas** |  |  |  |  |  |
| Lawns, parks, golf course, cemeteries | - | 39 | 61 | 74 | 80 |
| Pasture for grazing (not mowed) | - | 39 | 61 | 74 | 80 |
| Meadows (mowed for hay) | - | 30 | 58 | 71 | 78 |
| Brushy areas | - | 30 | 48 | 65 | 73 |
| Woods | - | 30 | 55 | 70 | 77 |