Photo credit: Adobe Stock

By Scott Hamilton, President, Hamilton Resource Economics

As of January 7th, more than 100,000 cfs (200,000 af/day) were flowing through the Delta to the Pacific Ocean when pumps that supply the State Water Project were operating at one-fifth of their capacity. As California struggles to recover from three years of intensive drought and the San Joaquin Valley desperately tries to restore its groundwater supplies, this management of such a scarce resource is mystifying. So, why weren’t the pumps operating at full capacity?

These maps show the distribution of delta smelt during the water year 2006, a year with a big first flush, like 2023. The solid blue dots show the distribution of delta smelt in the fall. Blue pie segments represent males. Pink pie segments represent females. The bigger the pie, the greater the number of delta smelt observed at a location. These maps indicate: that delta smelt are not located near the water project pumps in years with large first flush events until mid-February, that restricting pumping in January does not help delta smelt, and that most delta smelt are never near the pumps. Source: Hamilton Resource Economics, compiled using maps from the California Department of Fish and Wildlife.

The primary reason for the restrictions in mid-January was the need to protect the endangered delta smelt from entrainment at state and federal pumping plants in the Delta. Some background. Delta smelt are a small (2”) native fish that resides only in the Sacramento-San Joaquin Delta and adjoining waters. Delta smelt are mostly annual fish, meaning they typically hatch, grow, reproduce, and die in one year, although a few live two years. The California Department of Fish and Wildlife conduct fish surveys throughout the year in the Delta to detect changes in abundance and trends of many fish species, one of them being delta smelt. Some of these surveys have been conducted for more than 40 years. Consequently, scientists have some idea of when the fish will be in certain locations and why.

So back to the current regulation. The theory behind the regulation is that delta smelt disperse to shallow, turbid, fresh water where they spawn following the first big inflow event of the water year (commonly called a “first flush”, which started this water year at the end of December 2022). Then they typically stay in those areas. The premise is that pumping can be increased later because delta smelt will stay in those spawning areas away from the pumps. Unfortunately, the premise was based on a bad interpretation of a good scientific study.

A closer look at the data suggests the premise is without merit. When the first flush is very big, such as this year, delta smelt are far from the Delta pumps in January. A small percentage of them will move into the south Delta to spawn, generally starting around mid-February. So, given the hydrologic conditions in December and January, the regulation to protect delta smelt was unnecessary, but it cost the state as much as one-quarter of a million acre-feet of water.

Does any of this make sense? How can agency staff responsible for developing regulations so misinterpret scientific data and studies? Why is it so hard to change when the underlying premise is found to be faulty? Can misrepresentation of science in regulations be prevented? Tens of thousands of hatchery delta smelt (which have the same DNA as native fish) were added to the Delta last year to supplement the native population. Even if the projects do take some delta smelt when pumping, why can’t those impacts be mitigated by adding hatchery fish? These questions deserve answers.

Previous articleBuilding a Better Ranch with Ranchbot
Next articleWho Leads Us?