Civil engineering education, which encompasses much of hydraulic, hydrologic and environmental education, has changed over time. Several programs have experimented with 5-year undergraduate degrees, but most of these did not survive. More recently we have seen a trend in declining credit hours for a four-year bachelor's degree. During the first half of the twentieth century, most programs required 140 to 150 semester credit hours or more. Today, a 128 credit hour curriculum is quite common, and increasingly, a number of institutions are moving towards a 120 credit hour curriculum for civil engineering as legislative, college administrator and parental pressure mounts to control costs and minimize student debt. Several representative studies on engineering education have been produced and looking back in time include: