The last of new flood control improvements along the lower Santa Ana River are expected to wrap up this spring, part of a decades-long series of projects that federal and local officials say will better protect neighboring communities in the event of seriously rising water. The project – it involves 2.4 miles of the Santa Ana River’s north bank on both sides of the Gypsum Canyon Road bridge – is the final stage of the Corps’ almost three decades of work strengthening river infrastructure and improving flood protection along the 30 miles from the Prado Dam to the Pacific Ocean.