Wis. Admin. Code Department of Natural Resources NR 328.08

Current through November 25, 2024

Section NR 328.08 - Data requirements and site assessment methods

Applicants and department staff shall adhere to the following data requirements and site assessment methods:

(1) CALCULATION OF STORM-WAVE HEIGHT. The department shall provide applicants with worksheets and internet-based computer software for the purpose of estimating storm wave height. Computer software shall be mathematically designed based on Young and Verhagen (1996) and Young (1998). Storm-wave heights shall be estimated according to 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.

Note: 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.

Note: Statewide storm wind speeds are estimated from Naber Knox, P. 1996. Wind Atlas of Wisconsin. Wisconsin Geological and Natural History Survey, Bulletin No. 94.

(2) CALCULATION OF EROSION INTENSITY. Where an applicant or the department believes that, as a result of site conditions, storm-wave height as calculated in 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 internet-based computer software 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 EI and storm-wave height result in different energy categories, the site shall be placed in the category as determined by EI.

(3) BANK EDGE RECESSION MEASUREMENTS. Methods of measuring bank edge recession shall include all of the following: establishment of a physical measurement reference line between at least 2 headstakes; date-imbedded photographs showing the initial installation of the reference line and headstakes; reference distance measures to the bank lip shall be reported on department supplied forms; and time between separate measurements shall equal or exceed 3 months during the open-water season.

Table 1

Erosion Intensity (Ei) Score Worksheet

Applicants and department staff shall use this worksheet to calculate erosion intensity pursuant to s. NR 328.08(2).

SHORELINE VARIABLES

DESCRIPTIVE CATEGORIES

Erosion Intensity Value is Located in Parenthesis on Left Side of Each Category Box

ASSIGNED

AVERAGE FETCH¹- average distance (miles), across the open water to the opposite shore measure 45° other side of the perpendicular to the shoreline.

(0) <1/10

(2) 1/10 -1/3

(4) 1/3-1

(7) 1 -3

(10) 3-10

(13) 10-30

(16) >30

DEPTH AT 20 FEET, depth of water (feet) 20 feet from shoreline

(1) <1

(2) 1-3

(3) 3-6

(4) 6-12

(5) >12

DEPTH AT 100 FEET, depth of water (feet) 100 feet from shoreline

(1) <1

(2) 1-3

(3) 3-6

(4) 6-12

(5) >12

BANK HEIGHT ², height of bank (feet), measure from toe of the bank to top of the bank-lip.

(1)<1

(2) 1-5

(3) 5-10

(4) 10-20

(5) >20

BANK COMPOSITION

composition and degree of cementation of the sediments

(0) rock, marl, tight clay, well cemented sand (dig with a pick)

(7) soft clay, clayey sand, moderately cemented (easily dug with a knife)

(15) uncemented sands or peat (easily dug with your hand)

INFLUENCE OF ADJACENT STRUCTURES,

likelihood that adjacent structures are causing flank erosion at the site

(0) no hard armoring on either adjacent property

(1) hard armoring on one adjacent property

(2) hard armoring on both adjacent properties

(3) hard armoring on one adjacent property with measurable recession

(4) hard armoring on both adjacent properties with measurable recession adjacent to both structures

AQUATIC VEGETATION³

type and abundance of vegetation occurring in the water off the shoreline

(0) rocky substrates unable to support vegetation

(1) dense or abundant emergent, floating or submerged vegetation

(4) scattered or patchy emergent, floating or sub-mergent vegetation

(7) lack of emergent, floating or submer-gent vegetation

BANK VEGETATION,

type and abundance of the vegetation occurring on the bank face and immediately on top of the bank lip

(0) bank composed of rocky outcropping unable to support vegetation

(1) dense vegetation, upland trees, shrubs and grasses, including lawns

(4) clumps of vegetation alternating with areas lacking vegetation

(7) lack of vegetation (cleared), crop or agricultural land

BANK STABILITY, The degree to which bank and adjacent area (within 10 feet of the bank-lip) is stabilized by natural ground, shrub, and canopy vegetation (outside a 10' pier access corridor). Human disturbance is typified by tree removal, brushing, mowing, and lawn establishment.

(0) established lawn with few canopy trees

(1) established lawn with moderate to dense canopy trees

(4) moderate to dense natural ground vegetation and canopy trees with shrub layer substantially reduced; or few canopy trees with moderate to dense natural shrub layer.

(7) moderate to dense canopy trees with moderate to dense natural shrub layer; or other natural features prevents establishment of vegetation.

SHORELINE GEOMETRY

general shape of the shoreline at the point of interest plus 200 yards on either side.

(1) coves or bays

(4) irregular shoreline or straight shoreline

(8) headland, point, or island

SHORE ORIENTATION⁴

geographic direction the shoreline faces

(0) < 1/3 mile fetch

(1) north to east to south-southeast (349°-360°, 1°-168°)

(4) south to west-

southwest

(169°-258°)

(8) west to north-northwest (259°-349°)

BOAT WAKES⁵

proximity to and use of boat channels

(1) no channels within 100 yards, broad open water body, or constricted shallow water body; or channels within no-wake zones

(6) thoroughfare within 100 yards carrying limited traffic, or thoroughfare 100 yards to % mile offshore carrying intensive traffic

(12) thoroughfare within 100 yards carrying intensive traffic (unregulated boating activity)

EROSION INTENSITY SCORE (EI)

Note: Table 1 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.

1 Average fetch: The following diagram describes the calculation of average fetch.

See Image

2 Bank height: The following diagram describes the features of the bank for the purpose of accurately measuring bank height

See Image

3 Aquatic vegetation: Dense or abundant means that on average 50-100% 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 1-49% 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.

4 Shoreline Orientation: The following lake map shows an example of accurately determining shoreline orientation

See Image

5 Boating: A thoroughfare is identified as physical narrowing of the waterbody that by its nature intensifies boating activity near the shore. Thoroughfares which are 250 yards or wider are not scored 12 points, unless the depth contours of the thoroughfare constricts 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.

Wis. Admin. Code Department of Natural Resources NR 328.08

CR 02-099: cr. Register April 2005 No. 592, eff. 5-1-05.