New studies show the potential for restoring a small part of a river largely destroyed by Seven Oaks Dam.

Constructed by the US Army Corps of Engineers along the upper river in 2002, the design and operation of the dam disregarded downstream natural resources, including endangered species and plants. With a sole purpose of flood control, the dam eliminated the natural hydrology of the river, especially the periodic flood events which rejuvenate habitat for the San Bernardino kangaroo rat, Santa Ana suckerfish, and rare plants like the Santa Ana River woolly star and slender-horned spineflower. The US Fish and Wildlife Service (USFWS) permitted the dam with wholly inadequate mitigation, never having done necessary technical studies. The river became a shadow of its former self.

In late 2016, based upon EHL’s review of decades of regulatory history, the Center for Biological Diversity and EHL sued the Corps to compel “reconsultation” with USFWS on endangered species affected by the dam. Due to concerns over groundwater recharge, two local water districts intervened in the litigation on our side, and local flood control districts backed the Corps. One of the water districts suggested independent studies to determine if water discharges from the dam – anticipated by the federal permit but never undertaken – might show a path forward. 

While the litigation was put on hold, multiphase studies were undertaken by the districts, with EHL making a financial contribution. The initial results were devastating: even at full dam release volumes and using Mill Creek’s tributary flows, the amount of water would not overtop the incised river channel and rejuvenate endangered species habitat. However, based upon workshops that included experts retained by EHL as well as from the San Diego Zoo, the consultant team developed options to physically alter the floodplain, for example, with periodic water diversions, that might allow today’s smaller flows to create a biologically functional, albeit much smaller, floodplain than the historic one. Groundwater recharge could be a compatible use.

Much more work remains, and we need more collaboration from the Army Corps and the flood control districts. Nevertheless, EHL believes these interventions could tangibly help the endangered plants and animals of the river and allow the various parties to work together constructively. We commend our partners, the San Bernardino Valley Municipal Water District and the San Bernardino Valley Water Conservation District, and the consultant team, a consortium led by ICF International.

Two related projects – Habitat Conservation Plans (HCPs) under the Endangered Species Act – also show promise for river species. In July 2020, the “Wash Plan” HCP was approved. Led by the San Bernardino Valley Water Conservation District, it provides mitigation for ongoing water recharge and sand mining operations just below Seven Oaks Dam. Creative land exchanges consolidate conservation and impact areas, and restoration is also a component. The Upper Santa Ana River HCP, led by San Bernardino Valley Municipal Water District, focuses on the Santa Ana suckerfish, a gravely imperiled animal now reliant upon artificial water treatment plant discharges. Restoration of habitat along tributary streams is a key part of the draft plan, just released for public review and comment.