Rivers and the periodic replenishment of their lakes, floodplains, wetlands, estuaries, deltas and groundwater systems comprise the primary physical components of aquatic ecosystems. Yet, the intensive development of these aquatic systems is transforming the planet. Taming the natural variability in flow patterns not only isolates these formerly productive systems from the rivers that nourish them, it also invites land use encroachments that severely limit the potential for eventual restoration. Ironically, when upstream dams are constructed and operated to reduce the frequency of flooding, human settlements tend to occupy the floodplain. Thus, reductions in the frequency and magnitude of floods on many highly controlled rivers have actually increased the hazards of large floods and the associated economic losses.
When aquatic ecosystems are heavily developed, a myriad of ecosystem services are lost including: spawning and nursery habitat for fish; wetlands and riparian forests; floodplain food, forage and fibre production; nutrient cycling that drives the entire riverine food chain; flood attenuation; a variety of land uses that depend on natural groundwater replenishment; water supplies; natural water purification systems; recreation; and the beauty and serenity of pristine waterscapes that have fed the human spirit since time immemorial. As a consequence, aquatic ecosystems are in extremis around the world. Several recent estimates agree that some 35% of modern freshwater species are now extinct, endangered, or in sharp decline, a degree of peril perhaps more severe than any other type of ecosystem.
The San Francisco Bay-Delta is a classic example. Here, storage dams and an extensive system of levees have converted what was once the largest and most productive wetland complex west of the Mississippi into a precarious patchwork of farmlands and a highly vulnerable water supply conveyance system. The once-great expanse of wetlands has been reduced by 97%.
Beyond preventing further deterioration, the imperative for the future is to incrementally restore these damaged systems to achieve a flow and sediment regime that resembles natural conditions to the greatest extent possible. Restoring aquatic ecosystems provides a way for people to breathe new life into the rivers and estuaries that we rely upon but have unintentionally damaged. Restoration offers promise: not to turn back the clock and restore a state of unblemished nature, but to create a new future where robust economies thrive alongside healthy ecosystems.
Restoration is a complex interdisciplinary problem. There is rarely a simple solution, and every degraded river offers its own set of unique challenges. NHI employs an interdisciplinary team of engineers, ecologists, hydrologists, economists, planners, and lawyers to craft innovative solutions that are catered to the unique economic and ecological needs of a particular region. We call these restoration experiments “learning laboratories” because the objective is as much to advance knowledge of the efficacious restoration tools and techniques as to restore environmental functionality to the targeted site.
NHI develops creative strategies for re-engineering water resources infrastructure to achieve ecological restoration along with traditional flood control and water supply objectives. Our restoration philosophy is inspired by the notion of reconciliation ecology: the science of inventing, establishing and maintaining new habitats to conserve species diversity in places where people live, work or play.
NHI partners with other environmental organizations, water districts, and government agencies to illuminate the path toward restoration where conflicts over scarce water resources seem intractable. In the Sacramento-San Joaquin Delta, NHI has designed a series of restoration projects to both stabilize the delta as a water conveyance system and restore tidal marsh. Our interdisciplinary team has developed innovative strategies and conducted essential analysis that pointed the way toward restoration of Mono Lake and the San Joaquin River and promises similar hope for scores of other beleaguered watersheds such as the Klamath River.