Section NR 151.123 - Peak discharge performance standard(1) REQUIREMENT. By design, BMPs shall be employed to maintain or reduce the 1-year, 24-hour and the 2-year, 24-hour post-construction peak runoff discharge rates to the 1-year, 24-hour and the 2-year, 24-hour pre-development peak runoff discharge rates respectively, or to the maximum extent practicable. The runoff curve numbers in Table 2. shall be used to represent the actual pre-development condition. Table 2. Maximum Pre-Development Runoff Curve Numbers |
Runoff Curve Number | Hydrologic Soil Group |
A | B | C | D |
Woodland | 30 | 55 | 70 | 77 |
Grassland | 39 | 61 | 71 | 78 |
Cropland | 55 | 69 | 78 | 83 |
Note: Where the pre-development condition is a combination of woodland, grassland, or cropland, the runoff curve number should be pro-rated by area.
(2) EXEMPTIONS. This section does not apply to the following: (a) A post-construction site where the discharge is directly into a lake over 5,000 acres or a stream or river segment draining more than 500 square miles.(b) Except as provided under s. NR 151.121(5), a redevelopment post-construction site.(c) An in-fill development area of less than 5 acres.Wis. Admin. Code Department of Natural Resources NR 151.123
CR 09-112: cr. Register December 2010 No. 660, eff. 1-1-11.The intent of s. NR 151.123 is to minimize streambank and shoreline erosion under bank-full conditions.