The boards of the several counties shall be composed of representatives from within the county who are elected and compensated as provided in this section. Each board shall act under sub. (2), (3) or (5), unless the board enacts an ordinance, by a majority vote of the entire membership, to act under sub. (1). If a board enacts such ordinance, a certified copy shall be filed with the secretary of state.

   (1)   Self-organized counties.

      (a)    Number of supervisors and apportionment of supervisory districts. In each county with a population of at least 750,000, sub. (2) (a) and (b) applies. In counties with a population of less than 750,000 and more than one town, sub. (3) (a) to (c) applies. In counties with one town only, sub. (5) applies.

      (b)    Terms. The term of office of supervisors is 2 years. A board may determine whether the terms shall be concurrent or staggered. Supervisors shall be elected at the election to be held on the first Tuesday in April next preceding the expiration of their respective terms and shall take office on the 3rd Tuesday in April following their election. If the board determines that supervisors shall serve staggered terms, the board shall, by ordinance, provide for a division of supervisors into 2 classes, one class to be elected for one-half of a full term and the other class for a full term and thereafter the supervisors shall be elected for a full term. The board shall publish the ordinance as a class 1 notice, under ch. 985, or as a notice, as described under s. 59.14 (1m) (b), before publication of the notice of the election at which supervisors are to be elected.

      (c)    Compensation. The method of compensation for supervisors shall be determined by the board.

      (d)    Vacancies. A board may determine the procedure for filling a vacancy.

   (2)   Milwaukee County. In each county with a population of at least 750,000:

      (a)    Composition; supervisory districts. Within 60 days after the population count by census block, established in the decennial federal census of population, and maps showing the location and numbering of census blocks become available in printed form from the federal government or are published for distribution by an agency of this state, but no later than July 1 following the year of each decennial census, the board shall adopt and transmit to the governing body of each city and village wholly or partially contained within the county a tentative county supervisory district plan to be considered by the cities and villages when dividing into wards. The tentative plan shall specify the number of supervisors to be elected and shall divide the county into a number of districts equal to the number of supervisors, with each district substantially equal in population and consisting of contiguous whole wards or municipalities, except as authorized in sub. (3) (b) 2. Except as otherwise provided in this paragraph, the board shall develop and adopt the tentative plan in accordance with sub. (3) (b) 1. The tentative plan shall not include provision for division of any census block, as utilized by the U.S. bureau of the census in the most recent federal decennial census, unless the block is bisected by a municipal boundary or unless a division is required to enable creation of supervisory districts that are substantially equal in population. The board shall adopt a final plan by enacting an ordinance in accordance with sub. (3) (b) 2. to 4. Changes to the final plan shall be governed by par. (d) and sub. (3) (c).

      (b)    Election; term. For an election that is held before 2016, supervisors shall be elected for 4-year terms at the election to be held on the first Tuesday in April next preceding the expiration of their respective terms, and shall take office on the 3rd Monday in April following their election. For an election that is held in 2016 and thereafter, supervisors shall be elected for 2-year terms at the election to be held on the first Tuesday in April next preceding the expiration of their respective terms, and shall take office on the 3rd Monday in April following their election.

      (c)    Compensation.

         1.    Each supervisor shall be paid by the county an annual salary set by the board. The board may provide additional compensation for the chairperson, such that his or her salary may be an amount of up to 150 percent of the salary of a supervisor, and for the chairperson of the board’s finance committee, such that his or her salary may be an amount of up to 125 percent of the salary of a supervisor. Beginning with the term that commences in April 2016, the total dollar value of the annual salary and benefits that may be paid to a supervisor, other than the board chairperson and finance committee chairperson, may not exceed the annual per capita income of Milwaukee County as most recently determined by the U.S. bureau of the census and may be increased for a new term as provided in subds. 2. and 3., subject to the limit specified in subd. 4. Section 66.0505 applies to this paragraph.

         2.    The board may increase the salary specified in subd. 1., or as otherwise adjusted under this paragraph, by an amount that does not exceed the percentage increase in the U.S. consumer price index for all urban consumers, U.S. city average, for the period between the time that a supervisor’s salary was last set under subd. 1. or by the board, and the year before the year in which the salary increase is to take effect.

         3.    The board may increase the salary specified in subd. 1., or as otherwise adjusted under this paragraph, by an amount that exceeds the percentage increase in the U.S. consumer price index for all urban consumers, U.S. city average, for the period between the time that a supervisor’s salary was last set under subd. 1. or by the board, and the year before the year in which the salary increase is to take effect, except that such an increase may not take effect unless it is ratified by a majority vote of the electors in the county voting in a referendum on the proposed salary increase.

         4.    A supervisor may not receive any other benefits or compensation, including health insurance and pension benefits, not specifically authorized or required by law. The maximum total dollar value of the salary and benefits that a supervisor, other than the chairperson of the board and the chairperson of the finance committee, receives in any year may not exceed the annual per capita income of Milwaukee County as most recently determined by the U.S. bureau of the census.

      (d)    Changes during decade.

         1.    `Number of supervisors; redistricting.’ The board may, not more than once prior to November 15, 2010, decrease the number of supervisors after the enactment of a supervisory district plan under par. (a). In that case, the board shall redistrict, readjust, and change the boundaries of supervisory districts, so that the number of districts equals the number of supervisors, the districts are substantially equal in population according to the most recent countywide federal census, the districts are in as compact a form as possible, and the districts consist of contiguous municipalities or contiguous whole wards in existence at the time at which the amended redistricting plan is adopted, except as authorized in sub. (3) (b) 2. In the amended plan, the board shall adhere to the requirements under sub. (3) (b) 2. with regard to contiguity and shall, to the extent possible, place whole contiguous municipalities or contiguous parts of the same municipality within the same district. In the amended plan, the original numbers of the districts in their geographic outlines, to the extent possible, shall be retained. The chairperson of the board shall file a certified copy of any amended plan adopted under this subdivision with the secretary of state.

         2.    `Election; term.’ Any amended plan enacted under subd. 1. becomes effective on the first November 15 following its enactment, and first applies to the spring election following the plan’s effective date. Any amended plan enacted under subd. 1. shall remain in effect until the effective date of a redistricting plan subsequently enacted under par. (a). Supervisors elected from the districts created under subd. 1. shall serve for 4-year terms and shall take office on the 3rd Monday in April following their election.

   (3)   Other counties.

      (a)    Classification; maximum number of supervisors. Counties with a population of less than 750,000 and more than one town are classified and entitled to a maximum number of supervisors as follows:

         1.    Counties with a population of less than 750,000 but at least 100,000 shall have no more than 47 supervisors.

         2.    Counties with a population of less than 100,000 but at least 50,000 shall have no more than 39 supervisors.

         3.    Counties with a population of less than 50,000 but at least 25,000 shall have no more than 31 supervisors.

         4.    Counties with a population of less than 25,000 and containing more than one town shall have no more than 21 supervisors.

         5.    If the population of any county is within 2 percent of the minimum population for the next most populous grouping under this paragraph, the board thereof, in establishing supervisory districts, may employ the maximum number for such districts set for such next most populous grouping.

      (b)    Creation of supervisory districts.

         1.    Within 60 days after the population count by census block, established in the decennial federal census of population, and maps showing the location and numbering of census blocks become available in printed form from the federal government or are published for distribution by an agency of this state, but no later than July 1 following the year of each decennial census, each board shall propose a tentative county supervisory district plan setting forth the number of supervisory districts proposed by the board and tentative boundaries or a description of boundary requirements, hold a public hearing on the proposed plan and adopt a tentative plan. The proposed plan may be amended after the public hearing. The tentative plan shall divide the county into a number of districts equal to the number of supervisors, with each district substantially equal in population. The board shall solicit suggestions from municipalities concerning the development of an appropriate plan. Except as authorized in this subdivision, each district shall consist of whole wards or municipalities. Territory within each supervisory district to be created under the tentative plan shall be contiguous, except as authorized in subd. 2. In the tentative plan, the board shall, whenever possible, place whole contiguous municipalities or contiguous parts of the same municipality within the same district. If the division of a municipality is sought by the board, the board shall provide with the plan a written statement to the municipality affected by each proposed division specifying the approximate location of the territory from which a ward is sought to be created for contiguity purposes and the approximate population of the ward proposed to effectuate the division. The tentative plan shall not include provision for division of any census block unless the block is bisected by a municipal boundary or unless a division is required to enable creation of supervisory districts that are substantially equal in population. The board shall transmit a copy of the tentative plan that is adopted to each municipal governing body in the county.

         2.    Within 60 days after every municipality in the county adjusts its wards under s. 5.15, the board shall hold a public hearing and shall then adopt a final supervisory district plan, numbering each district. Territory within each supervisory district created by the plan shall be contiguous, except that one or more wards located within a city or village which is wholly surrounded by another city or water, or both, may be combined with one or more noncontiguous wards, or one or more wards consisting of island territory as defined in s. 5.15 (2) (f) 3. may be combined with one or more noncontiguous wards within the same municipality, to form a supervisory district.

         3.    The populations of supervisory districts under the tentative plan shall be determined on the basis of the federal decennial census and any official corrections to the census issued on or before the date that the tentative plan is adopted to reflect the correct population of the county and municipalities and blocks within the county on April 1 of the year of the census. The populations of supervisory districts under the final plan shall be determined on the basis of the federal decennial census and any official corrections to the census to reflect the correct populations of the county and the municipalities and blocks within the county on April 1 of the year of the census, if the corrections as they affect any municipality are issued prior to division of the municipality into wards under s. 5.15, or if a municipality is not divided into wards, prior to adoption of the final plan.

         4.    The chairperson of the board shall file a certified copy of the final districting plan with the secretary of state. Unless otherwise ordered under sub. (6), a plan enacted and filed under this paragraph, together with any authorized amendment that is enacted and filed under this section, remains in effect until the plan is superseded by a subsequent plan enacted under this subsection and a certified copy of that plan is filed with the secretary of state.

      (c)    Changes during decade; municipal boundary adjustments.

         1.    After the enactment of a plan of supervisory districts under par. (b), the board may amend the plan to reflect a municipal incorporation, annexation, detachment or consolidation. The number of supervisory districts in the county shall not be changed by any action under this subdivision.

         2.    Within 60 days after enactment or adoption of a revised division ordinance or resolution under s. 5.15 (4) (a), the board shall amend the county supervisory district plan under par. (b) to reflect any renumbering of the wards specified in the plan.

         3.    The districts under the amended plan shall be substantially equal in population according to the most recent countywide federal census and shall be in as compact a form as possible. The board shall adhere to the requirements of par. (b) 2. with regard to contiguity and shall, to the extent possible, place whole contiguous municipalities or contiguous parts of the same municipality within the same district. In the amended plan, the original numbers of the districts in their geographic outlines, to the extent possible, shall be retained. An amended plan becomes effective on the first November 15 following its enactment.

         4.    The chairperson of the board shall file a certified copy of any amended plan under this paragraph with the secretary of state.

      (cm)    Changes during decade; reduction in size.

         2.    `Petition and referendum.’ Except as provided in subd. 3., the electors of a county may, by petition and referendum, decrease the number of supervisors at any time after the first election is held following enactment of a decennial supervisory district plan under par. (b). A petition for a change in the number of supervisors may be filed with the county clerk. Prior to circulating a petition to decrease the number of supervisors in any county, a petitioner shall register with the county clerk, giving the petitioner’s name and address and indicating the petitioner’s intent to file such a petition. No signature on a petition is valid unless the signature is obtained within the 60-day period following such registration. The petition shall specify the proposed number of supervisors to be elected. Within 14 days after the last day for filing an original petition, any other petitioner may file an alternative petition with the county clerk proposing a different number of supervisors to be elected, and, if the petition is valid, the alternative proposed in the petition shall be submitted for approval at the same referendum. An alternative petition is subject to the same registration and signature requirements as an original petition. Each petition shall be in the form specified in s. 8.40 and shall contain a number of signatures of electors of the county equal to at least 25 percent of the total votes cast in the county for the office of supervisor at the most recent spring election preceding the date of filing. The county clerk shall promptly determine the sufficiency of a petition filed under this subdivision. Upon determination that a petition is sufficient, or if one or more valid alternative petitions are filed, upon determination that the petitions are sufficient, the county clerk shall call a referendum concurrently with the next spring or general election in the county that is held not earlier than 70 days after the determination is made. The question proposed at the referendum shall be: “Shall the board of supervisors of …. County be decreased from …. members to …. members?”. If one or more alternative valid petitions are filed within 14 days after the last day that an original petition may be filed, the question relating to the number of supervisors shall appear separately. The first question shall be: “Shall the size of the county board of supervisors of …. County be decreased from its current membership of …. members?”. Any subsequent question shall be: “If so, shall the size of the board be decreased to …. members?”. Each elector may vote in the affirmative or negative on the first question and may then vote in the affirmative on one of the remaining questions. If the first question is not approved by a majority of the electors voting on the question, any subsequent question is of no effect. If the question is approved by a majority of the electors voting on the question, or, if more than one question is submitted, if the first question is approved by a majority of the electors voting on the question, the board shall enact an ordinance prescribing revised boundaries for the supervisory districts in the county. The ordinance shall be enacted in accordance with the approved question or, if more than one question is submitted, in accordance with the choice receiving a plurality of the votes cast. The districts are subject to the same requirements that apply to districts in any plan enacted by the board under subd. 1. If the board has determined under sub. (1) (b) to adopt staggered terms for the office of supervisor, the board may change the expiration date of the term of any supervisor to an earlier date than the date provided under current ordinance if required to implement the redistricting or to maintain classes of members. The county clerk shall file a certified copy of any redistricting plan enacted under this subdivision with the secretary of state.

         3.    `Limitation.’ If the number of supervisors in a county is decreased by the board or by petition under this paragraph, no further action may be taken by the board or by petition under this paragraph in that county until after enactment of the next decennial supervisory district plan by the board under par. (b).

         4.    `Election; term.’ Any redistricting plan enacted under subd. 1. takes effect on November 15 following its enactment and first applies to the election of supervisors at the next spring election following the effective date that immediately precedes the expiration of the terms of office of supervisors in the county. Any reduction in the number of supervisory districts under subd. 2. that is approved at a spring election shall be enacted in the form of a redistricting plan no later than November 15 following that election and shall first apply to the election of supervisors at the next spring election immediately preceding the expiration of the terms of office of supervisors in the county, and any reduction in the number of supervisory districts under subd. 2. that is approved at a general election shall be enacted in the form of a redistricting plan no later than the 2nd succeeding November 15 following that election and shall first apply to the election of supervisors at the next spring election following that November 15 immediately preceding the expiration of the terms of office of supervisors in the county. Any redistricting plan enacted under subd. 1. or 2. shall remain in effect until the effective date of any subsequent redistricting plan enacted under sub. (3) (c) or until the effective date of a redistricting plan subsequently enacted under par. (b). Supervisors elected from the districts created under subd. 1. or 2. shall serve for 2-year terms and shall take office on the 3rd Tuesday in April following their election.

      (d)    Election and term of supervisors. Supervisors are county officers, shall be elected for 2-year terms at the election to be held on the first Tuesday in April in even-numbered years and shall take office on the 3rd Tuesday in April of that year.

      (e)    Vacancies. If a vacancy occurs on the board, the board chairperson, with the approval of the board, shall appoint a person who is a qualified elector and resident of the supervisory district to fill the vacancy. The successor shall serve for the unexpired portion of the term to which the person is appointed, unless the board orders a special election to fill the vacancy, in which case the person appointed shall serve until his or her successor is elected and qualified. The board may, if a vacancy occurs before June 1 in the year preceding expiration of the term of office, order a special election to fill the vacancy. If the board orders a special election during the period beginning on June 1 and ending on November 30 of any year, the special election shall be held concurrently with the succeeding spring election. If the board orders a special election during the period beginning on December 1 and ending on May 31 of the succeeding year, the special election shall be held on the Tuesday after the first Monday in November following the date of the order. A person so elected shall serve for the residue of the unexpired term.

      (f)    Compensation. Each supervisor shall be paid a per diem by the county for each day that he or she attends a meeting of the board. Any board may, at its annual meeting, by a two-thirds vote of all the members, fix the compensation of the board members to be next elected. Any board may also provide additional compensation for the chairperson.

      (g)    Mileage. Each supervisor shall, for each day that he or she attends a meeting of the board, receive mileage for each mile traveled in going to and returning from the meetings by the most usual traveled route at the rate established by the board under s. 59.22 as the standard mileage allowance for all county employees and officers.

      (h)    Limitation on compensation. Except for services as a member of a committee as provided in s. 59.13 no supervisor shall be paid for more days’ attendance on the board in any year than is set out in this schedule: in counties having a population of less than 25,000, 20 days; at least 25,000 but less than 100,000, 25 days; at least 100,000 but less than 750,000, 30 days.

      (i)    Alternative compensation. As an alternative method of compensation, in counties having a population of less than 750,000, including counties containing only one town, the board may at its annual meeting, by a two-thirds vote of the members entitled to a seat, fix the compensation of the supervisors to be next elected at an annual salary for all services for the county including all committee services, except the per diem allowance for services in acquiring highway rights-of-way set forth in s. 84.09 (4). The board may, in like manner, allow additional salary for the members of the highway committee and for the chairperson of the board. In addition to the salary, the supervisors shall receive mileage as provided in par. (g) for each day’s attendance at board meetings or for attendance at not to exceed 2 committee meetings in any one day.

      (j)    Supplementary compensation. The board, in establishing an annual salary, may enact an ordinance providing for a per diem for all committee meetings attended in excess of 40 committee and board meetings.

   (4)   Compatibility. No county officer or employee is eligible for election or appointment to the office of supervisor, but a supervisor may also be a member of a committee, board or commission appointed by the county executive or county administrator or appointed or created by the county board, a town board, a mosquito control district, the common council of his or her city, the board of trustees of his or her village or the board of trustees of a county institution appointed under s. 46.18.

   (5)   Counties having only one town. In all counties containing one town only, the board shall consist of the members of the town board and one supervisor from every village. A supervisor from a village shall be elected at the time the other village officers are elected. A majority of the members shall constitute a quorum of the county board. Each supervisor shall receive compensation and mileage as provided in sub. (3) (f) and (g). The chairperson of the board elected under s. 59.12 (1) may be, but need not be, the same person who is elected chairperson of the town board under s. 60.21 (3) (a).

   (6)   Enforcement of division requirement. If a county fails to comply with sub. (2) (a) or (3) (b), any municipality located in whole or in part within the county or any elector of the county may submit to the circuit court for the county within 14 days from the expiration of either 60-day period under sub. (2) (a) or (3) (b) a proposed tentative supervisory district plan or a final plan for creation of supervisory districts in compliance with this section. If the court finds that the existing division of the county into supervisory districts fails to comply with this section, it shall review the plan submitted by the petitioner and after reasonable notice to the county may promulgate the plan, or any other plan in compliance with this section, and the plan shall be in effect until superseded by a plan adopted by the board in compliance with this section.