Paragraph 21 I1

Without limitation on the scope of paragraph 20, but subject always to the provisions of that paragraph as to reasonableness, the requirements which the Agency may make under that paragraph include conditions requiring the undertaker at its own expense to construct such protective works, whether temporary or permanent, before or during the construction of the specified works (including the provision of flood banks, walls or embankments or other new works and the strengthening, repair or renewal of existing banks, walls or embankments) as are reasonably necessary—

by reason of any specified work.