67. If at any time after the completion of a specified work, not being a work vested in the GYPA, the GYPA gives notice to the undertaker informing it that the state of maintenance of the specified work appears to be such that the specified work is causing or is likely to cause adverse effects to the river, the undertaker must, on receipt of such notice together with supporting evidence of the matters asserted by the notice to the reasonable satisfaction of the undertaker take such steps as may be reasonably necessary to put the specified work in such state of maintenance as not to cause such adverse effect and if the undertaker fails to do so, the GYPA may make and do in and upon the land of the undertaker or the GYPA all such works to put the specified work in such state of maintenance as before and the cost, expenses and losses incurred by the GYPA in so doing must be repaid to the GYPA by the undertaker.