Va. Code § 33.2-413
In case the earthen portion of a dam has been washed away and it is determined by the Commissioner of Highways that the washout was caused by a spillway of insufficient opening to carry floodwater, the dam shall not be restored for the purpose of impounding water unless the owner or occupier agrees with the Commissioner of Highways to the construction of a spillway with adequate opening, conforming to plans and specifications of the Department. In the event that such construction is required, the Commissioner of Highways shall be responsible for such part of the cost as would be necessary to provide a bridge with sufficient opening to carry the floodwater of the stream, and the owner or occupier of the dam shall be required to pay the difference in cost, if any, of providing adequate floodgates and spillways in addition to the bridge.
Va. Code § 33.2-413