Panel Releases Long-term Operations Biological Opinion Actions Review

A panel of experts convened by the Delta Science Program has released its independent scientific review of the implementation of the Long-Term Operations Opinions (LOO) Reasonable and Prudent Alternative (RPA) Actions for the prior year’s operations to protect salmon and steelhead.

The review focused on implementation of the National Marine Fisheries Service (NMFS) Clear Creek RPA actions and the Spring 2012 Delta Operations action. The latter was conducted instead of the NMFS’ RPA action that restricted Delta exports based on San Joaquin River inflow as called for in a joint stipulation agreement for water year 2012. The overall goal of this peer review was to inform NMFS as to the scientific efficacy of the prior year’s actions and to make suggestions for 2013.

The review panel was generally encouraged by the response to its prior year’s recommendations, noting an improved research focus on the effect of RPA actions on the behavior and survival of fish. Compared with previous reviews, the panel indicated that it also appreciated the opportunity to review a reduced number of actions in more depth. Panel members provided several insights and recommendations for implementation of the RPA actions in their report.

Clear Creek Actions

The Clear Creek actions are concentrated on a few key aspects of the stream environment affecting the spawning and rearing of salmon and steelhead in an important tributary of the Sacramento River: the volume and temperature of stream flows in Clear Creek, and the presence of suitable spawning gravel.

Clear Creek is one of the larger tributaries of the lower Sacramento River and is considered critical habitat for Central Valley steelhead and spring run Chinook salmon. Removal of a small dam in 2000 opened up 12 miles of potential spawning and rearing habitat for these species. Since then, numbers of both steelhead and spring run salmon have increased while efforts to improve habitat quality in Clear Creek for these endangered species continue. Clear Creek is also an important spawning tributary for fall run Chinook salmon with runs of around 16,000 fish in recent years.

Central Valley Fall Chinook abundance in 2007-2010 collapsed to only 24 percent of the 1992-96 average. However, in Clear Creek the decline was less severe (74 percent). Tributaries like Clear Creek are important for sustaining salmon population levels as well as improving our understanding of the factors that contribute to the resilience of the species.

Both the volume and temperature of stream flows in Clear Creek, and the presence of suitable spawning gravel are identified as key factors for successful reproduction of salmonids. Water volume and temperature depend on operation of upstream reservoirs on Clear Creek and the Trinity River. The panel made several recommendations for improved monitoring and modeling to make better use of the available cold water. It also made suggestions for improved evaluation of gravel augmentation and channel maintenance flow actions; again expressing the need to relate these to fish and other ecosystem goals.

Spring 2012 Delta Operations Actions

The spring 2012 Delta Operations actions, also known as the Joint Stipulation actions, included installation of a rock barrier at the head of Old River in the southern Delta and evaluation of the effects of changing flows in southern Delta channels on the migration and survival of juvenile steelhead. Using acoustic tags, juvenile steelhead were tracked under a range of flow conditions. The panel identified a number of technical problems with the studies but agreed with some of the conclusions including the apparent lack of a relationship between fish movement and particle tracking model results. This suggests that such models (simulating the movements of inanimate objects) are poor predictors of the effects of Old and Middle River (OMR) flows on the fate of steelhead in the Delta. It also suggests that a more sophisticated descriptor of the response of fish to flow cues should be incorporated into the particle tracking model.

The panel also noted the absence of a relationship between OMR flow and smolt movement and survival under the flow conditions investigated. The panel stated that discerning behavioral responses of fish to tidal flows is crucial for understanding variation in salmonid survival but that information was not used in the spring 2012 studies. To improve future survival studies, the review panel provided a detailed analytical framework for assessing the effects of flows in Delta channels on fish survival in the complex tidal environment of the Delta.

The review panel suggested a more systematic incorporation of climate change information into flow management decision making. Near-term climate conditions (e.g., global patterns in sea water temperatures driving El NiƱo-Southern Oscillation events) could be used to improve hydrologic predictions.

Panel members suggested that a review of annual flow records to detect any predictable patterns influenced by the Pacific Decadal Oscillation as well as proposed scenarios for climate change in California might be useful exercises to “fine-tune” future management options.

This was the third LOO (formerly OCAP-Operations Criteria and Plan) annual review. These reviews have been held annually, no later than November 30 of each year, consistent with the NMFS biological opinion. The report fulfills a request to the Delta Science Program from NMFS, the United States Bureau of Reclamation, and United States Fish and Wildlife Services to provide annual independent external review of implementation of the RPAs in the NMFS and the USFWS Long-term Operations biological opinions for the state and federal water projects.

Detailed information on the Long-term Operations Opinions Annual Review can be found here.