Section 393.1006 - Documentation to be submitted - notice to be published - examination of proposal - authorization of commission, when - pretax revenues, factors to be considered - revised rate schedule, filed when - rulemaking authority1.(1) At the time that a water corporation files a petition with the commission seeking to establish or change an ISRS, it shall submit proposed ISRS rate schedules and its supporting documentation regarding the calculation of the proposed ISRS with the petition, and shall serve the office of the public counsel with a copy of its petition, its proposed rate schedules and its supporting documentation.(2) Upon the filing of a petition, and any associated rate schedules, seeking to establish or change an ISRS, the commission shall publish notice of the filing.2.(1) When a petition, along with any associated proposed rate schedules, is filed pursuant to the provisions of sections 393.1000 to 393.1006, the commission shall conduct an examination of the proposed ISRS.(2) The staff of the commission may examine information of the water corporation to confirm that the underlying costs are in accordance with the provisions of sections 393.1000 to 393.1006, and to confirm proper calculation of the proposed charge, and may submit a report regarding its examination to the commission not later than sixty days after the petition is filed. No other revenue requirement or ratemaking issues shall be examined in consideration of the petition or associated proposed rate schedules filed pursuant to the provisions of sections 393.1000 to 393.1006.(3) The commission may hold a hearing on the petition and any associated rate schedules and shall issue an order to become effective not later than one hundred twenty days after the petition is filed.(4) If the commission finds that a petition complies with the requirements of sections 393.1000 to 393.1006, the commission shall enter an order authorizing the water corporation to impose an ISRS that is sufficient to recover appropriate pretax revenues, as determined by the commission pursuant to the provisions of sections 393.1000 to 393.1006.3. A water corporation may effectuate a change in its rate pursuant to this section no more often than two times every twelve months.4. In determining the appropriate pretax revenues, the commission shall consider only the following factors: (1) The current state, federal, and local income or excise tax rates;(2) The water corporation's actual regulatory capital structure as determined during the most recent general rate proceeding of the water corporation;(3) The actual cost rates for the water corporation's debt and preferred stock as determined during the most recent general rate proceeding of the water corporation;(4) The water corporation's cost of common equity as determined during the most recent general rate proceeding of the water corporation;(5) The current property tax rate or rates applicable to the eligible infrastructure system replacements;(6) The current depreciation rates applicable to the eligible infrastructure system replacements;(7) In the event information called for in subdivisions (2), (3), and (4) is unavailable and the commission is not provided with such information on an agreed-upon basis, the commission shall refer to the testimony submitted during the most recent general rate proceeding of the water corporation and use, in lieu of any such unavailable information, the recommended capital structure, recommended cost rates for debt and preferred stock, and recommended cost of common equity that would produce the average weighted cost of capital based upon the various recommendations contained in such testimony.5.(1) An ISRS shall be calculated based upon the amount of ISRS costs that are eligible for recovery during the period in which the surcharge will be in effect and upon the applicable customer class billing determinants utilized in designing the water corporation's customer rates in its most recent general rate proceeding. The commission shall, however, only allow such surcharges to apply to classes of customers receiving a benefit from the subject water utility plant projects or shall prorate the surcharge according to the benefit received by each class of customers; provided that the ISRS shall be applied in a manner consistent with the customer class cost-of-service study recognized by the commission in the water corporation's most recent general rate proceeding, if applicable, and with the rate design methodology utilized to develop the water corporation's rates resulting from its most recent general rate proceeding.(2) At the end of each twelve-month calendar period that an ISRS is in effect, the water corporation shall reconcile the differences between the revenues resulting from an ISRS and the appropriate pretax revenues as found by the commission for that period and shall submit the reconciliation and a proposed ISRS adjustment to the commission for approval to recover or refund the difference, as appropriate, through adjustment of an ISRS.6.(1) A water corporation that has implemented an ISRS pursuant to the provisions of sections 393.1000 to 393.1006 shall file revised rate schedules to reset the ISRS to zero when new base rates and charges become effective for the water corporation following a commission order establishing customer rates in a general rate proceeding that incorporates in the utility's base rates subject to subsections 8 and 9 of this section eligible costs previously reflected in an ISRS.(2) Upon the inclusion in a water corporation's base rates subject to subsections 8 and 9 of this section of eligible costs previously reflected in an ISRS, the water corporation shall immediately thereafter reconcile any previously unreconciled ISRS revenues as necessary to ensure that revenues resulting from the ISRS match as closely as possible the appropriate pretax revenues as found by the commission for that period.7. A water corporation's filing of a petition to establish or change an ISRS pursuant to the provisions of sections 393.1000 to 393.1006 shall not be considered a request for a general increase in the water corporation's base rates and charges.8. Commission approval of a petition, and any associated rate schedules, to establish or change an ISRS pursuant to the provisions of sections 393.1000 to 393.1006 shall in no way be binding upon the commission in determining the ratemaking treatment to be applied to eligible infrastructure system replacements during a subsequent general rate proceeding when the commission may undertake to review the prudence of such costs. In the event the commission disallows, during a subsequent general rate proceeding, recovery of costs associated with eligible infrastructure system replacements previously included in an ISRS, the water corporation shall offset its ISRS in the future as necessary to recognize and account for any such overcollections.9. Nothing contained in sections 393.1000 to 393.1006 shall be construed to impair in any way the authority of the commission to review the reasonableness of the rates or charges of a water corporation, including review of the prudence of eligible infrastructure system replacements made by a water corporation, pursuant to the provisions of section 386.390.10. The commission shall have authority to promulgate rules for the implementation of sections 393.1000 to 393.1006, but only to the extent such rules are consistent with, and do not delay the implementation of, the provisions of sections 393.1000 to 393.1006. Any rule or portion of a rule, as that term is defined in section 536.010, that is created under the authority delegated in this section shall become effective only if it complies with and is subject to all of the provisions of chapter 536 and, if applicable, section 536.028. This section and chapter 536 are nonseverable and if any of the powers vested with the general assembly pursuant to chapter 536 to review, to delay the effective date, or to disapprove and annul a rule are subsequently held unconstitutional, then the grant of rulemaking authority and any rule proposed or adopted after August 28, 2003, shall be invalid and void.