(1)    Objectives. To aid in the fulfillment of the state‘s role as trustee of its navigable waters, to promote public health, safety and general welfare and to protect natural resources, it is declared to be in the public interest to make studies, establish policies, make plans, authorize municipal construction site erosion control and storm water management zoning ordinances for the efficient use, conservation, development and protection of this state’s groundwater, surface water, soil and related resources and establish a state storm water management plan for the efficient use, conservation, development and protection of this state’s groundwater, surface water, soil and related resources while at the same time encouraging sound economic growth in this state. The purposes of the municipal ordinances and state plan shall be to further the maintenance of safe and healthful conditions; prevent and control water pollution; prevent and control soil erosion; prevent and control the adverse effects of storm water; protect spawning grounds, fish and aquatic life; control building sites, placement of structures and land uses; preserve ground cover and scenic beauty; and promote sound economic growth.

   (2)   State storm water management plan. The department, in consultation with the department of safety and professional services, shall promulgate by rule a state storm water management plan. This state plan is applicable to activities contracted for or conducted by any agency, as defined under s. 227.01 (1) but also including the office of district attorney, unless that agency enters into a memorandum of understanding with the department of natural resources in which that agency agrees to regulate activities related to storm water management. The department shall coordinate the activities of agencies, as defined under s. 227.01 (1), in storm water management and make recommendations to these agencies concerning activities related to storm water management.

   (3)   Standards related to storm water and certain construction activities.

         1.    Except as restricted under subd. 2., the department shall establish by rule uniform statewide standards for all of the following:

            a.    Activities related to construction site erosion control at sites that have a land disturbance that is one acre or more in area.

            b.    Activities related to construction site erosion control at sites that have a land disturbance that is less than one acre and to which ss. 101.1206 and 101.653 do not apply.

            c.    Storm water management.

         2.    The department, in cooperation with the department of transportation, shall establish by rule uniform statewide standards for activities related to construction site erosion control and storm water management if those activities concern street, highway, road or bridge construction, enlargement, relocation or reconstruction.

         3.    Uniform statewide standards for storm water management established under this paragraph are applicable to the state plan under sub. (2). The department shall require a city, village, town, or county to comply with uniform statewide standards established under this paragraph for any construction site erosion control and storm water management zoning ordinance enacted under s. 59.693, 60.627, 61.354 or 62.234.

         4.    The department shall identify low-cost practices which would enable a person to comply with these uniform statewide standards.

      (b)    The uniform statewide standards for construction site erosion control at sites described in par. (a) 1. a. and b. shall provide for the regulation of any construction activity, at such a site, that:

         1.    Involves the grading, removal of protective ground cover or vegetation, excavation, land filling or other land disturbing activity which affects an area of 4,000 square feet or more.

         2.    Involves the excavation or filling or a combination of excavation and filling which affects 400 cubic yards or more of dirt, sand or other excavation or fill material.

         3.    Involves street, highway, road or bridge construction, enlargement, relocation or reconstruction.

         4.    Involves the laying, repairing, replacing or enlarging of an underground pipe or facility for a distance of 300 feet or more.

         5.    Requires a subdivision plat approval or a certified survey.

      (c)    The uniform statewide standards for storm water management shall provide for the regulation of any construction activity which:

         1.    Is a residential development with a gross aggregate area of 5 acres or more.

         2.    Is a residential development with a gross aggregate area of 3 acres or more with at least 1.5 acres of impervious surfaces.

         3.    Is a development other than a residential development with a gross aggregate area of 3 acres or more.

         4.    Is likely to result in storm water runoff which exceeds the safe capacity of the existing drainage facilities or receiving body of water, which causes undue channel erosion, which increases water pollution by scouring or the transportation of particulate matter or which endangers downstream property.

      (d)    If the department determines that rules promulgated under s. 281.16 (2) prescribe performance standards that meet the requirements for establishing uniform statewide standards under this subsection, the department’s rules promulgated under s. 281.16 (2) satisfy the rule-making requirements under this subsection and shall apply as if they were promulgated under this subsection.

   (3m)   Requirements for ordinances. A city, village, town, or county may enact an ordinance regulating the conduct regulated under this section only if the ordinance strictly conforms with uniform statewide standards established under sub. (3).

   (4)   Model ordinances; state plan; distribution. The department shall prepare a model zoning ordinance for construction site erosion control at sites described in sub. (3) (a) 1. a. and b. and for storm water management in the form of an administrative rule. The model ordinance is subject to s. 227.19 and other provisions of ch. 227 in the same manner as other administrative rules. Following the promulgation of the model ordinance as a rule, the department shall distribute a copy of the model ordinance to any city, village, town or county that submits a request. The department shall distribute a copy of the state plan to any agency which submits a request.

   (5)   Cooperation. The department, the municipalities, and all state agencies shall cooperate to accomplish the objective of this section. To that end, the department shall consult with the governing bodies of municipalities to secure uniformity of regulations, shall prepare model ordinances under sub. (4), shall extend assistance to municipalities under this section, shall prepare the plan under sub. (2), shall obtain uniformity through the implementation of this plan and the utilization of memoranda of understanding which are substantially similar to the plan, and shall extend assistance to agencies under this section.

   (6)   Exceptions.

      (a)    Notwithstanding subs. (3) and (3m), a city, village, town, or county may enact and enforce provisions of an ordinance that are stricter than the uniform standards for storm water management established by the department under this section if the stricter provisions are necessary to do any of the following:

         1.    Control storm water quantity or peak flow to address existing flooding problems or prevent future flooding problems, except that an ordinance under this subdivision may not require more than 90 percent of the difference between the pre-development annual runoff volume at a site and the post-development annual runoff volume at that site to be retained on site.

         2.    Comply with federally approved total maximum daily load requirements.

      (b)    Subsection (3m) does not apply to provisions of an ordinance enacted by a city, village, town, or county if the provisions of the ordinance regulate storm water management relating to existing development or redevelopment, as defined in NR 151.002, Wis. Adm. Code.