County highway departments are also required to meet a “maintenance of effort” for local revenues according to T.C.A. § 67-3-901(d). It states a county shall be eligible to receive those revenues to be distributed directly to it from the tax increases imposed by Acts 1985, Ch. 419, and Acts 1985, Ch. 454, effective 1985, only if it appropriates and allocates funds for road purposes from local revenue sources in an amount not less than the average of the five preceding fiscal years, except bond issues and federal revenue sharing proceeds shall be excluded from the five year average computation. If a county fails to appropriate at least such average amount for road purposes, then the amount of “gas tax” revenue that would otherwise be allocable to a county would be reduced by the amount of the decrease below the five year average.