1.6 feet = R
R = 19.7 inches
Culvert diameter = 39.4 inches
Culvert size = 42 inches
NR 320.10(3)(3) Culvert length determination. The proper culvert length is determined by the following calculation: NR 320.10(3)(a)(a) To determine the length of any culvert, use the following equation: L (Length of Culvert) = W + 4H + 2
W = Width of road top
H = Height of culvert + average depth of road fill
H is multiplied by 4 as a constant for the side slope angle (2 x 2:1)
2 is added as a constant for 1 foot of pipe extension beyond fill
Length of culvert needed for 10’ road top, 24” (2”) diameter pipe, 1’ average road fill depth, 2:1 side slopes, 1’ pipe extension beyond fill:
L = 10’ road top + 4(2’ culvert + 1’ fill) + 2’ extension
L = 10 + 4(2+1) + 2
L = 10 + 4x2 + 4x1 + 2
L = 10 + 8 + 4 + 2
L = 24 feet
NR 320.10 HistoryHistory: CR 24-051: cr. Register January 2026 No. 841, eff. 4-1-26. NR 320.11NR 320.11 Site assessment methods for erosion control structures on inland lakes and flowages. Applicants and department staff shall use any of the following data requirements and site assessment methods for potentially exempt riprap under s. NR 320.04 (12) and shoreline erosion control structures individual permit applications under s. NR 320.06 for inland lakes and flowages: NR 320.11(1)(1) Calculation of storm-wave height. The department shall provide applicants with worksheets and a web page calculator for the purpose of estimating storm-wave height. The storm-wave height calculator shall be mathematically designed based on Young and Verhagen (1996) and Young (1997) by applying a storm wind speed of 35 miles per hour (51.45 ft/sec), fetch at the applicant’s shore protection site, and the average depth along that fetch. To record fetch, applicants shall measure the longest unobstructed straight-line distance originating from the shore protection site across the water surface to the opposite intersect with the shore. To estimate average depth applicants shall examine a lake map, sum the reported depths along the fetch, and divide by the number of recorded values. At least 5 equally placed intervals along the fetch shall be used. NR 320.11 NoteNote: To use a web version of the storm-wave height calculator, go to dnr.wisconsin.gov, keyword “calculating energy along a shoreline.”
NR 320.11 NoteNote: The citation for Young (1997) is as follows: Young, I.R. 1997. The growth rate of finite depth wind-generated waves. Coastal Engineering, Vol. 32, pp. 181-195. The citation for Young and Verhagen (1996) is as follows: Young, I.R. and L.A. Verhagen. 1996. The growth of fetch limited waves in finite water depth. Coastal Engineering, Vol. 29, pp. 47-78.
NR 320.11 NoteNote: Statewide storm wind speeds are estimated from Naber Knox, P. 1996. Wind Atlas of Wisconsin. Wisconsin Geological and Natural History Survey, Bulletin No. 94.
NR 320.11(2)(2) Calculation of erosion intensity. When an applicant or the department believes that, as a result of site conditions, storm-wave height as calculated under sub. (1) may inaccurately predict the degree of erosion, the erosion intensity score may be calculated to determine erosion. The department shall provide applicants with worksheets and a web page calculator for the purpose of calculating erosion intensity. When the department or applicants assess erosion at the shore protection site, they shall apply methods outlined in Table 1 to calculate an erosion intensity score. Wherever erosion intensity and storm-wave height result in different energy categories, the site shall be placed in the category as determined by the erosion intensity score. Table 1. Erosion Intensity (EI) Score Worksheet
NR 320.11 NoteNote: The EI Score Worksheet is adapted from Knutson, P. L., H. H. Allen, and J. W. Webb, 1990. “Guidelines for Vegetative Erosion Control on Wave−Impacted Coastal Dredged Material Sites”, Dredging Operations Technical Support Program Technical Report D−90−13,U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS 39180, 35 pp.
NR 320.11 Note1. Average fetch: The following diagram describes the calculation of average fetch.
NR 320.11 Note2. Bank height: Bank height is the vertical measure (feet) from the bank toe to the top of the bank lip, irrespective of water level changes.
NR 320.11 Note3. Aquatic vegetation: Dense or abundant means that on average 50 to 100% of the bottom is visually obstructed by plants during the growing season, defined by the dates June 1 through September 15. Scattered or patchy means that on average 1 to 49% of the bottom is visually obstructed by plants during the growing season, defined by the dates June 1 through September 15. Absent means that on average < 1% of the bottom is visually obstructed by plants during the growing season, defined by the dates June 1 through September 15.
NR 320.11 Note4. Shoreline orientation: The following lake map shows an example of accurately determining shoreline orientation.
NR 320.11 Note5. Boating: A thoroughfare is identified as physical narrowing of the waterbody that by its nature intensifies boating activity near the shore. Thoroughfares that are 250 yards or wider are not scored 12 points, unless the depth contours of the thoroughfare constrict boating activity in close proximity to one shore and the traffic is intensive. Intensive traffic is defined by a location where at least 50% of the public boating access available must pass through the thoroughfare to reach the open water of the lake, provided the waterway has a total of more than 60 car−trailer units. Limited traffic is defined by a location where at least 30% of the public boating access available must pass through the thoroughfare to reach the open water of the lake, provided the waterway has a total of more than 40 car−trailer units.
NR 320.11(3)(a)(a) Except as provided in pars. (b) and (c), the method of measuring bank edge recession shall include all of the following: NR 320.11(3)(a)1.1. Establishment of a physical measurement reference line between at least 2 headstakes. NR 320.11(3)(a)2.2. Date-imbedded photographs showing the initial installation of the reference line and headstakes. NR 320.11(3)(a)4.4. Time between separate measurements shall be of 3 months or more during the open-water season. NR 320.11(3)(b)(b) As an alternate to the bank edge recession measurements method identified in par. (a), if 2 or more years of LiDAR elevation data are available for a site, the LiDAR elevation data may be used to determine the average annual rate of bank edge recession by comparing the horizontal distance the bank lip has moved using a GPS point and dividing this measurement by the difference in the number of years between datasets. NR 320.11(3)(c)(c) As an alternate to the recession measurement methods identified in par. (a) or (b), the severity of shoreline erosion may be identified using average annual rate, in feet per year, of shoreline recession with measurements from historic aerial imagery over a period of 20 years. This method may be excluded, or the evaluation period abbreviated, if imagery is unavailable or obscured by canopy. NR 320.11 HistoryHistory: CR 24-051: cr. Register January 2026 No. 841, eff. 4-1-26; correction in (intro.), Table 1 made under s. 35.17, Stats., Register January 2026 No. 841. NR 320.12NR 320.12 Site Assessment methods for erosion control structures on streams. Applicants and department staff shall use the following data requirements and site assessment methods for potentially exempt riprap under s. NR 320.04 (12) and shoreline erosion control structures individual permit applications under s. NR 320.06 for streams. NR 320.12(1)(1) Calculation of stream bank erosion potential index. The department shall provide applicants with worksheets and a web page calculator for the purpose of calculating the bank erosion potential index (BEPI). When the department or applicants assess erosion at the bank stabilization site, they shall apply methods outlined in the BEPI worksheet in Table 1 to calculate a BEPI score. For each continuous treatment site of 300 feet or less, applicants shall submit at least one BEPI assessment. For continuous treatments greater than 300 feet, applicants shall conduct and submit BEPI assessments at 150-foot intervals along the treatment site. Table 1. Bank Erosion Potential Index (BEPI) Score Worksheet
NR 320.12 NoteNote: The Bank Erosion Potential Index Worksheet is adapted from Rosgen, David L. “A Practical Method of Computing Streambank Erosion Rate”, Wildland Hydrology Inc., Pagosa Springs, CO, 10 pp.
NR 320.12 Note1. Bank Materials If bank material is composed of bedrock outcrop, stop with the BEPI assessment at this point; the reported total BEPI score is assumed equal to 0.
NR 320.12 Note2. Maximum bank height means the vertical measure (feet) from the bank toe to the top of the bank lip, irrespective of changes in the water level. Bank toe is the inflection or bending point between the bank face and stream bed.
NR 320.12 Note3. To measure the bank slope (degrees), the rise and run must be measured from the bank toe to the top of the bank lip. With your measure tape or stick, place the end firmly on the bank toe, parallel to the bank face and measure up to the bank lip to find the rise or max bank height. Subsequently, measure the run from the bank toe to the bank lip. From these measures, one should be able to calculate the bank slope with the formula ‘bank slope= inverse tangent (rise/run)’. Additionally, the BEPI Calculator is available on the Department’s website https://dnr.wisconsin.gov/. This website automatically calculates the bank slope and BEPI score after inputting fields for bank materials, structures upstream, OHWM height, maximum bank height, distance to bank face, bank layering/stratification, bank vegetation, and thalweg location. NR 320.12 Note
NR 320.12 Note4. Stratification or bank layering means soils consisting of alternating layers of varying soils or textures.
NR 320.12 Note5. Bank vegetation is the type and abundance of vegetation occurring between the ordinary high water mark (OHWM) and the bank lip. To assess the abundance of vegetation on the targeted bank, apply a 10 foot wide window of assessment from the OHWM to the top of the bank. The following percentages are assigned for the categories: bare soil visible over less than 30% of the surface area = dense vegetation; bare soil visible across 30 to 59% of the surface area = clumps of vegetation; bare soil visible across 60 to 90% of the surface area = vegetation sparse; bare soil visible across > 90% of the surface area = vegetation absent. Root wads, tree falls, and snags on the bank are considered in this assessment, because of their influence on thalweg, sediment transport, scour, and bank protection. After assessing the percentage of bare soil in the ‘box’, record its associated point value.
NR 320.12 Note6. Thalweg means the deepest part of the channel or the location of fastest current. To find the thalweg, the channel must be divided into thirds. The applicant needs to perform one or a mixture of tests for the three segments in determining its location. The following tests are suggested: float an object such as an orange peel down the stream to find the segment of fastest current, find the segment with the bubble line visible at the water’s surface, or find the deepest part of the channel, if safe. After locating the thalweg, record its proximity to the tested bank, adjacent (closest), center, or opposite (furthest) and record its associated point value.
NR 320.12(2)(a)(a) Methods of measuring bank edge recession shall include all of the following: NR 320.12(2)(a)1.1. Establishment of a physical measurement reference line between at least 2 headstakes. NR 320.12(2)(a)2.2. Date-imbedded photographs showing the initial installation of the reference line and headstakes. NR 320.12(2)(a)4.4. Time between separate measurements of 3 months or more during the open-water season. NR 320.12(2)(b)(b) As an alternate to the bank edge recession measurements method identified in par. (a), if 2 or more years of LiDAR elevation data are available for a site, the LiDAR elevation data may be used to determine the average annual rate of bank edge recession by comparing the horizontal distance the bank lip has moved using a GPS point and dividing this measurement by the difference in the number of years between datasets. NR 320.12(2)(c)(c) As an alternate to the recession measurement methods identified in par. (a) or (b), the severity of shoreline erosion can be identified using average annual rate, in feet per year, of shoreline recession with measurements from historic aerial imagery over a period of 20 years. The average annual rate of lateral migration shall be measured at the apex of the channel bend using historic aerial imagery over a period of 20 years. This method may be excluded, or the evaluation period abbreviated, if imagery is unavailable or obscured by canopy. NR 320.12 HistoryHistory: CR 24-051: cr. Register January 2026 No. 841, eff. 4-1-26. NR 320.13(1)(1) No person may place a structure in, or a crossing 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 320.13(2)(2) Noncompliance with the provisions of s. 30.12, 30.13, 30.123, 30.20, or 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, fine, or imprisonment. The department may seek abatement under s. 30.294, 30.298 (5), or 30.03 (4) (a), Stats., for any activity in violation of s. 30.12, 30.13, 30.123, 30.20, or 30.206, Stats. NR 320.13(3)(3) If an activity may be authorized by a general permit under s. 30.206, Stats., failure of an applicant to follow the procedural requirements of the general permit may not, by itself, result in abatement of the activity. NR 320.13(4)(4) When an after-the-fact permit application has been filed with the department, the department shall follow the procedures in s. NR 300.20 for violations. NR 320.13(5)(5) Any violation of this chapter shall be treated as a violation of the statutes this chapter interprets or is promulgated under. NR 320.13 HistoryHistory: CR 24-051: cr. Register January 2026 No. 841, eff. 4-1-26.
