The secretary of transportation is hereby authorized and directed to make noninterest bearing loans and advances to any county to provide such county with funds to pay its share of the cost of building or reconstructing a bridge over a navigable stream and construction of the approaches thereto where such stream comprises the boundary line or part of the boundary line between counties and which bridge is located on a county major collector road which is not a part of the regular state highway system, provided that the total amount of such loans and advances outstanding at any one time shall not exceed $2,000,000.