245. The requirements or conditions which the drainage authority may make under paragraph 244 include conditions requiring the undertaker at its own expense to construct such protective works (including any new works as well as alterations to existing works) as are reasonably necessary—
(a)to safeguard any ordinary watercourse against damage, or
(b)to secure that the efficiency of any ordinary watercourse for flood defence or land drainage purposes is not impaired and that the risk of flooding is not otherwise increased, by reason of the specified work in relation to the ordinary watercourse.