Questions and Answers
Regarding the U.S. Fish and Wildlife Service’s
Supplemental Biological Opinion
for the 2003 Missouri River Operations
What is the supplemental biological opinion for the 2003 Missouri River Operations and how does it relate to the biological opinion provided to the Corps in November 2000 concerning the operations of the Missouri River Main Stem Reservoir System?
The U. S. Fish and Wildlife Service’s supplemental biological opinion analyzes the effects of the Corps of Engineers’ 2003 water management plan on the endangered least tern and pallid sturgeon and the threatened piping plover for the period from May 1 to August 15, 2003.
This supplemental biological opinion represents a collaborative effort between the Service and the Corps of Engineers and considers habitat conditions and new information not considered in the November 2000 biological opinion. It provides short-term compliance with the Endangered Species Act while acknowledging that the Service and the Corps will be addressing the long-term operations of the Missouri River and the long-term conservation and recovery needs of the federally-listed species during consultation on the Master Manual which will begin almost immediately.
This supplemental biological opinion, valid for a portion of the 2003 water year only, is an attachment to the Service’s 2000 biological opinion regarding operations for the Missouri River Main Stem system. It does not supersede the 2000 biological opinion or set a precedent for future water plans.
What is Corps of Engineers’ 2003 water management plan?
The Corps’ 2003 water management plan sets a release rate of 26,000 cubic feet per second (cfs) from Gavins Point Dam near Yankton, South Dakota for the period from about May 8 to 20 when terns and plovers begin nesting.
Immediately following the stabilization of the river stage at that level, a field survey will be conducted to identify any at-risk nesting sites. If a potential exists for a significant number of nesting sites to be at risk at 26,000 cfs flows, flows will be raised to no more than 27,000 cfs to minimize the potential future loss of nests, eggs, and chicks. Further increases throughout the summer may be necessary to support downstream flow targets as tributary contributions to the river dry up.
How does the 2003 water management plan differ from the Corps’ 2003 Annual Operating Plan?
The 2003 water management plan is a combination of "steady flow" features from the plan presented in the Final 2003 Annual Operating Plan and elements of a "flow-to-target" plan that would meet authorized purposes while conserving more water in the three biggest reservoirs.
It takes advantage of the likelihood of effective downstream tributary flows during the early part of the nesting season through an initial flat release rate. These tributary flows will allow for lower releases from the dams during the nesting season. If runoff conditions permit, those releases will be maintained throughout the nesting season. If downstream flow targets cannot be met at that rate, they will be increased to in order to meet them.
Additionally, use of the three Kansas River Corps reservoirs that are authorized to provide Missouri River flow support will be used if appropriate. They could be used to provide additional water to meet the Kansas City flow target, which may reduce the release needed from Gavins Point dam, thus limiting impacts to birds. However, there is currently insufficient water in the Kansas reservoirs to provide Missouri River flow support. Minimization efforts are in place to reduce the impacts to the birds if additional flows from Gavins Point dam are required.
How will the 2003 water management plan affect the least tern, piping plover and pallid sturgeon?
Terns and Plovers:
Reservoir releases under the 2003 water management plan are expected to have less impact (flooding of eggs and chicks) on nesting terns and plovers than the flow-to-target proposal.
Although the 2003 water management plan will increase the availability of habitat early in the nesting season compared to a flat release, less total habitat will available later in the season when flows are increased to support downstream flow targets.
However, new information, since the 2000 Biological Opinion, suggests that the rate of habitat degradation since the habitat was created following the1997 floods, may be slower than expected. More importantly, the impacts to productivity due to loss of that habitat are not what we expected. In other words, the birds have continued to have higher productivity (higher than the historic average) in spite of the declining rates of habitat.
We anticipate that productivity this year will be as good as last year because we are exposing as much high elevation habitat as possible, while limiting the low elevation habitats (i.e. habitats less than 6 inches above river surface). Forcing birds to nest on higher elevation habitats will allow chicks to escape to higher parts of the island if flows are increased to meet navigation targets. It will also allow Corps biologists to move nests and eggs to higher elevations if necessary. We also expect that by providing more habitat under this flow scenario, as opposed to the flat release, birds will initiate nesting early and fledge birds before additional flows may be needed to meet navigation targets. We also anticipate that the reservoirs this year will continue to supply the abundant and productive habitats that they supplied last year both on Lakes Oahe and Sakakawea.
Changes in reservoir releases under the new plan, the continued availability of river and reservoir habitats, the results of a population modeling exercise that showed a one-time loss of piping plovers (at the proposed levels) is not likely to jeopardize species recovery, the habitat enhancement measures being implemented this year by the Corps (e.g., vegetation removal practices), and the Corps ongoing management program for the birds (e.g., predator control) were all factors in assessing impacts to nesting terns and plovers.
The Service and the Corps believe the combination of these factors and the status of the birds, allows navigation requirements to be met while not jeopardizing the species this year.
Previously, the Corps had proposed to bring least tern and piping plover eggs and chicks into captivity as a means of offsetting impacts to the species resulting from an increase in flows throughout the nesting period. The Corps and Service have reached agreement that this approach is not in the best interest of the species, is inconsistent with existing policies, and will only be used in the future to meet specific research needs agreed to by both agencies.
Insufficient water runoff in the system due to the on-going drought will prevent the release of increased spring flows needed to provide spawning cues to pallid sturgeon. Since we don’t anticipate natural reproduction of pallids this year, the Service will again stock year-old pallids into the system this spring.
While lower summer flows would provide slow, shallow backwater areas for young fish to rest, feed, and grow, these year-old pallids will have passed the critical one-year mark and will not be as vulnerable to predation by larger fish species. Sandbar habitat will still be necessary to provide invertebrate populations for foraging. The area between Fort Peck and Gavins Point dams provides the necessary habitat requirements for pallids. The area below Gavins Point dam will continue to be restored by the Corps to provide backwater areas.
These are only interim measures. The long-term survival of pallid sturgeon will depend on a more natural hydrograph consisting of an increase in spring flows and declining summer flows.
What are the Service’s long-term recommendations for restoring ecological health to the Missouri River?
The Services believes that variable river flows are necessary to provide for the long-term ecological health of the Missouri River and the long-term conservation needs of the federally-listed threatened and endangered species.
The recommendations as set forth in the 2000 biological opinion will help achieve those goals.
Last update: 4/21/03