In his richly detailed The Fall and Rise of the Wetlands of California’s Great Central Valley, Philip Garone explains a bit about the origin of wildlife refuges that I never knew:

During the early decades of the twentieth century, much of the Sacramento Valley was converted to profitable rice production. However, because the valley’s natural wetlands had been reclaimed, crop depredations that followed led to a crescendo of calls by the same farmers who had benefited from the valley’s reclamation to create wetland refuges in the valley. Some of the earliest motivations behind the creation of these refuges in the Sacramento Valley stemmed, therefore, more from economic interests  than from an ecological awareness of the importance of wetlands….