(1g)    In this section:

      (a)    “Catastrophic highway failure” means the sudden failure of a major element or segment of the highway system due to a cause that is external to a highway, but does not include any failure primarily attributable to gradual and progressive deterioration or lack of proper maintenance of a highway.

      (b)    “Disaster” means any of the following:

         1.    A severe storm, flood, fire, tornado, mudslide, or other natural event external to a highway or a catastrophic highway failure.

         2.    An event or recurring damage caused by any governmental unit or person acting under the direction or approval of, or permit issued by, any governmental unit and in response to an event described in subd. 1.

      (c)    “Governmental unit” means the state or any state agency, as defined in s. 20.001 (1); any county, city, village, town, or other political subdivision of the state; or the federal government or any of its agencies.

      (d)    “Highway” means a highway, as defined in s. 340.01 (22), that is not on the state trunk highway system.

   (1m)   

      (a)    When any highway is damaged by a disaster, the county highway committee, or the governing body of the municipality having jurisdiction over the maintenance of the highway, may adopt a petition for aid under this section and file a certified copy of the petition with the department. To be eligible for aid the petition shall be filed not later than 2 months after the occurrence of the disaster damage, except as provided in par. (b). All such petitions shall state the dates on which the disaster damage occurred and as nearly as practical state the location, nature, and extent of the damage.

      (b)    The department may extend the filing deadline under par. (a) if it appears reasonably likely that federal disaster aid may be forthcoming or when widespread or continuous disaster damage makes an evaluation of damage difficult.

      (c)    A county or municipality having jurisdiction over the facilities damaged may apply for both state and federal aid for damage to the facilities pending a determination of eligibility. If federal aid is granted for damage to a particular facility, the federal aid shall be in lieu of aid otherwise available for such damage under this section.

   (2)   The department shall make such investigation as it deems necessary and within 6 months from the date of filing the petition shall make its determination as to the granting of aid, the amount thereof, and the conditions under which it is granted. In making its determination the department shall cause an estimate to be made of the cost of repairing or replacing the facilities damaged or destroyed to standards and efficiency similar to those existing immediately before the damage or destruction, and also an estimate of the cost of reconstructing the facilities to a higher type or improving any such facilities if determined to be warranted and advisable. Except as provided in subs. (2m) and (6), the amount of aid payable for damage caused by a disaster described in sub. (1g) (b) 1. shall be 75 percent of the cost of repair or replacement to standards similar to those existing immediately before the damage or destruction, plus 50 percent of the increased cost of the reconstruction to a higher type or the improvement of any of the facilities. Except as provided in subs. (2m) and (6), the amount of aid payable for damage caused by a disaster described in sub. (1g) (b) 2. shall be 70 percent of the cost of repair or replacement to standards similar to those existing immediately before the damage or destruction. The department may revise estimates on the basis of additional facts. The county, town, village, or city shall pay the remainder of the cost not allowed as aid, but this shall not invalidate any other provision of the statutes whereby the cost may be shared by the county and the town, village, or city.

   (2m)   Subject to sub. (6), if the department’s estimate under sub. (2) of the cost of repair or improvement of the facilities determined by the department to be eligible for aid is $15,000 or less, the department shall offer the petitioner an amount of aid equal to 75 percent of the total amount of the department’s estimate for damage caused by a disaster described in sub. (1g) (b) 1. or 70 percent of the total amount of the department’s estimate for damage caused by a disaster described in sub. (1g) (b) 2. If the petitioner accepts aid under this subsection, the aid shall be paid to the petitioner or, subject to sub. (5), the county, and no other form of aid is available under this section for the repair or improvement of such facilities.

   (3)   Aid allotted under sub. (2) shall be held to the credit of the county, town, city or village for not more than 2 years or for such other period as the department may grant, and, except as otherwise provided in this section, shall be paid to the treasurer thereof upon presentation to and approval by the department of certified statements setting forth the cost of the construction, reconstruction, repair or improvement of the facilities determined by the department to be eligible for aid. The certified statement shall set forth separately the amount expended on each such facility. The aid to be paid shall be the summation of the amounts determined or revised under sub. (2), as adjusted by the certified statements approved by the department. This subsection does not apply to aid awarded under sub. (2m).

   (5)   Any town, city or village may, and at the discretion of the department shall, arrange to have such work for which aid is granted performed by the county, and in such case, on order of the town, city or village, the aid from the state for such work shall be paid to the county.

   (6)   The department may not pay aid under this section in excess of $1,000,000, in connection with disaster damage resulting from a single disaster, unless the payment of aid is approved by the governor.

   (7)   Beginning in the 2nd fiscal year of the 2013-15 fiscal biennium, and in the 2nd fiscal year of each fiscal biennium thereafter, the department shall calculate the amount of aid paid under this section, during the biennium, in excess of $1,000,000, in connection with disaster damage resulting from a single disaster. The amount calculated under this subsection shall be transferred under s. 20.855 (4) (fr) from the general fund to the transportation fund in the 2nd fiscal year of each fiscal biennium.