Section 1. The taxing bodies of the various counties, cities, boroughs, towns, townships and school districts, may abate real estate taxes imposed by them for the tax years 1971 or 1972, if the real property upon which the tax was imposed was damaged or destroyed by flood during that year: Provided, That the amount of any tax abated shall be in direct proportion to the damage to the property as measured by a reduction in the assessed valuation of the property by the local assessing authority using the same assessment valuation factors, criteria, and procedures in use prior to the disaster. Local assessing authorities are hereby authorized to assess flood damaged properties retroactive to January 1, of the year the property was damaged to reflect property reductions due to flood damage. In the event that such tax has been paid, the taxing bodies may refund such taxes: Provided, however, That the amount abated by any taxing body shall not exceed twenty-five thousand dollars ($25,000) for any single property. (1 amended June 21, 1973, P.L.65, No.27)