Many of Northern Ireland’s rivers and lakes have a history of engineering interventions which have had an important role in the growth of the economy. Embankments, erosion protection and dredging have allowed urban development and cultivation of agricultural land adjacent to rivers and lakes. Weirs have helped irrigate crops and generate energy. Bridges, culverts and other similar structures underpin Northern Ireland’s transport network. We have also physically modified many of our waters for water supply and treatment, coastal defence/protection, forestry, fisheries and for navigational and recreational purposes. The resulting changes to the physical habitat of our water environment include the straightening and deepening of rivers, lowering of lake water levels, the reinforcement of banks, the culverting of rivers and the installation of bridges, weirs and impoundments.