Spreck Rosekrans is an Economic Analyst at EDF.

Amidst the recent (media frenzy ) about Delta water supplies, it seems worth noting that many scientists and environmentalists have been warning for decades that it will not be possible to sustain the valuable and unique Bay-Delta ecosystem if we continue to divert increasing amounts of water from the Delta and the rivers that feed it.

It also seems worth noting that the "Wanger" diversion reductions are not so large when considered in a historical context – under the “Wanger” decision State Water Project customers would receive as much exported water as they did only ten years ago. The recent Biological Opinion reductions need to be considered in this same context.

The chart below shows the history of State Water Project deliveries compared against projections of what would be allowed under the recent federal court ruling (2007) and under the more permissive State Board’s Water Quality Control Plan (1995). Unfortunately, as evidenced by the dramatic fish population declines in recent years, we have found that the Water Quality Control Plan clearly does not provide for the needs of Delta smelt.

And it is not just the smelt. Salmon and a number of other fish species depend on freshwater flows as well. The smelt is the Delta's canary in the coal mine. When the canary begins to have problems, it is a safe bet that conditions are not healthy for other species either.

We of course agree with DWR Director Lester Snow that there are other ecosystem “stressors”, including pollution and invasive species, beyond the diversions of fresh water upstream of, within and from the Delta. But if we want to save the rich and diverse Delta ecosystem, we must allow enough fresh water to flow through as confirmed by Judge Wanger and now by the Biological Opinion.