Required Culvert area (square feet) = H x (W1 + W2)
NR 320.07(2)(2) Culvert sizing. Once the required culvert area has been determined, the applicant can identify the proper culvert size by reviewing the following tables. The minimum size culvert needed to pass flows must have an area that is as much or more than the required culvert area. For example, the recommended culvert size for a culvert area calculation of 8.50 square feet would be 42″. Table 1. Round culvert diameters and corresponding culvert area.
Culvert diameter (in.) Culvert area (sq. ft.)
18 1.80
24 3.10
30 4.90
36 7.10
42 9.60
48 12.60
54 15.90
60 19.60
66 23.80
NR 320.07 NoteNote: To find the area of any round culvert, use the following equation:
NR 320.07 NoteCulvert diameter (in.) divided by 2 = _____ divided by 12 = _____ (radius in ft.)
NR 320.07 NoteRadius x Radius x 3.14 = _________ (area of culvert in sq. ft.)
Table 2. Pipe arch dimensions and corresponding culvert area.
Pipe width or span (in.) Pipe height or rise (in.) Culvert area (sq. ft.)
43 27 6.4
50 31 8.7
58 36 11.4
65 40 14.3
72 44 17.6
73 55 22.0
85 54 25.3
81 59 26
87 63 31
95 67 35
103 71 40
NR 320.07(3)(3) Culvert length determination. The proper culvert length is determined by the following calculation: NR 320.07 HistoryHistory: CR 04-084: cr. Register April 2005 No. 592, eff. 5-1-05. NR 320.08(1)(1) Noncompliance with the provisions of ss. 30.12, 30.123, 30.20 and 30.206, Stats., this chapter, or any conditions of an exemption, general permit or individual permit issued by the department, constitutes a violation and may result in a forfeiture. The department may seek abatement under s. 30.294, Stats., for any activity in violation of ss. 30.12, 30.123, 30.20 and 30.206, Stats. NR 320.08(2)(2) If the activity may be authorized by a general permit under s. 30.206, Stats., failure of an applicant to follow the procedural requirements may not, by itself, result in abatement of the activity. NR 320.08(3)(3) When an after-the-fact permit application has been filed with the department, the department shall follow the procedures in ch. NR 300 for violations. NR 320.08(4)(4) Any violation of these rules shall be treated as a violation of the statutes they interpret or are promulgated under. NR 320.08(5)(5) No person may place a bridge or culvert in or over a navigable waterway if the activity is not eligible for an exemption, authorized by a general permit or individual permit issued under this chapter, or otherwise authorized under this chapter. NR 320.08 HistoryHistory: CR 04-084: cr. Register April 2005 No. 592, eff. 5-1-05; CR 22-013: am. (3) Register June 2023 No. 810, eff. 7-1-23.
