Biological Impacts on Reclamation Operations from Climate Change
What Reclamation operations will be affected by climate change's impact on biological resources? How great will the effects be? How can Reclamation respond to insure water supply reliability?
Climate change has the potential to produce new operational constraints for Reclamation water managers. Water supplies may be altered as the climate warms. Climate models predict a variety of effects depending on latitude, altitude, and other factors. But a few water supply changes predicted include: reduced snowpack in many areas, changes in rainfall amount and temporal distribution of precipitation. While water supply is of high importance to Reclamation other parameters may change, e.g. temperature.
On the demand side, changes in precipitation and temperature would affect consumptive water use requirements on irrigated lands. The sum effects of climate change on supplies and demands could affect Reclamation's ability to meet contractual water obligations.
Ecologically, climate and hydrologic changes could affect fish spawning migrations, reducing reproductive success (e.g. fall run Chinook salmon), and increasing the probability of future ESA listings. Before new ESA listings, Reclamation may be required by NMFS or FWS to change dam releases to meet fish life history requirements.
Climate change could lead to modifications in water temperatures and potentially stimulate the growth rate of invasive mussels, leading to increased biofouling of physical structures. Reclamation managers could respond by implementing new maintenance and mussel-removal schedules. These new schedules could minimize the effect of biofouling in critical Reclamation structures.
Need and Benefit
Reclamation needs to meet its contractual water delivery schedules. This research will insure that biological effects will not impair Reclamation's ability to meet its delivery schedules in the face of climate change. Furthermore, Reclamation has a responsibility to manage water resources in a environmentally sound manner. To accomplish this, Reclamation should manage aquatic systems to provide for the continued existence of native species, especially those that are now rare.
Thorough comprehension and management of biological resources in the presence of climate change could benefit Reclamation by facilitating stable fish populations; allowing understanding of fish's physiological processes that can limit production; determining maintenance schedules necessary to minimize biofouling due to invasive mussel settlement; and reducing water delivery losses from pest plant obstructions. These actions can save water, reduce operational constraints, and allow us to improve water supply reliability for meeting Reclamation's mission.
Climate change could have a variety of effects on fish. Climate change could change the temporal distribution of precipitation. The temporal distribution of precipitation is a strong influence on ground water in the Cle Elum Basin (Bowen et al. In Review). In turn in the Cle Elum (tributary to the Yakima), the ground water drives hyporheic flow. We showed that changes in discharge can influence the hyporheic flow in the fall when spring chinook spawn; but, these changes may not affect egg survival (Bowen et al. In Review). We propose to identify appropriate fisheries models, e.g. EDT, SALMOD, etc., to take field research like that described in Bowen et al., use it to parameterize models, and use these model outcomes for management scenario planning.
Climate change and the increase of water temperatures will have direct impacts on fish populations through their physiology. Fishes' physiological mechanisms are temperature dependent. Geospatial ranges of fishes are determined largely by water temperature, which influences metabolism, growth, activity, reproduction, and immune function. Water temperature increases will result in species geographic range changes and extirpation of some species from their current locations. Increased temperatures also influence water chemistry (e.g., dissolved oxygen concentration and ph). Oxygen solubility decreases with higher temperatures, while fish oxygen demand increases with increases in temperature. Thus, there is an imbalance and metabolic needs for oxygen may not be met. Fish must relocate to a more suitable habitat, attempt to live in a compromised state, or perish. We will inventory fish species in Reclamation's regions and determine which fish are at the peripheries of their temperature tolerances. These inventories can be used to tailor operations and management decisions.
Mussel infestations are causing physical obstruction of flow in water conveyance systems, ranging from roughening to complete blockage. Increasing temperatures may increase the range of the invasive mussels, the rate of spread of these mussels and increase the growth rate of mussels. The ongoing proliferation of mussel populations threatens to seriously impact Reclamation operations, resulting in the interruption of hydropower and water delivery at significant economic costs. We will use quantitative methods to prioritize high risk water bodies to maximize efficiency of prevention, monitoring and control. This will make Reclamation more efficient reducing costs in the long term.
We need to mitigate for the impacts of climate change on infrastructure maintenance requirements caused by pest plant species. For example Eurasian Water Millfoil in the Truckee Canal constrains water flow. The growth rate of EWM will increase as temperature increases and the growing season lengthens. Growth models can be used to specify EWM removal schedules and provide efficient maintenance planning.
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