...S&P Global Ratings lowered its underlying rating (SPUR) for credit program on Anchor Bay School District, Mich.'s general obligation (GO) debt one notch to 'A-' from 'A'. The outlook is negative. The rating action reflects our opinion of the district's significantly deteriorated available reserves, which we no longer consider commensurate with its higher-rated peers. At the same time, S&P Global Ratings assigned its '##' program rating and stable outlook and 'A-' SPUR and negative outlook to the district's roughly $97.035 million series 2020 unlimited-tax GO refunding bonds. The negative outlook reflects our opinion of the uncertainty of exactly how much per-pupil-aid money the district would lose and if management's actions to compensate would be sufficient to offset lost revenue, coupled with increasing labor and benefit costs. The district's full-faith-credit-and-resources pledge and agreement to levy ad valorem property taxes, without limit as to rate or amount, secure the GO debt....