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Feds Plan For Climate Change In Columbia Basin: Earlier Runoff, Lower Flows In Late Summer
Posted on Friday, August 05, 2011 (PST)

Three federal agencies have been collaborating on a climate change initiative launched in 2008 that called for the development of common and consistent climate change data for use in the three agencies’ longer-term planning activities for operation of Columbia-Snake hydro system for power production, and to assure safe passage up and downstream for salmon and steelhead.


Generally, a steady warming over time is expected to result in more wintertime runoff from the mountain snowpacks that rim the Columbia River basin and less spring-summer runoff, Rick Pendergrass of the Bonneville Power Administration, Pat McGrane of the Bureau of Reclamation and Jim Barton of the U.S. Army Corps of Engineers said during their presentation to the Northwest Power and Conservation Council last month.


That means that the region’s rivers will have lower flows in late summer.


“What happens is that runoff ends in August and September,” McGrane said. “But as long as you have reservoir storage you’re not going to be so bad off.” Those that need to draw water from rivers in late summer, however, could run short.


Storage reservoirs may have to be drawn down earlier, in fall and winter rather than in spring, and deeper to allow for earlier refill flows, Barton said.


Such runoff scenarios could lead to increased power generation in fall and winter and less generation in the late summer when energy demand is high.


“Traditionally historical climate data has been used when evaluating proposed actions; however, there is growing evidence that the global and regional climate system is changing and is expected to continue changing,” according to a summary report on work undertaken by the agencies over the past two years in collaboration with other federal, state and tribal entities.


This effort was led by the River Management Joint Operating Committee, a forum of water managers, hydrologists, and power schedulers from the three agencies.


That collaboration the three agencies has produced three technical reports that identify how climate change could impact hydrology and water supplies in the Columbia River basin and the potential impacts of the operation of the 31 federal dams on the Columbia River and its tributaries. The study, called Climate and Hydrology Datasets for use in the RMJOC Agencies’ Longer-Term Planning Studies resulted in the following reports:


-- Part I – “Future Climate and Hydrology Datasets (completed December 2010). Collects a consistent set of future climate and hydrologic data from the Climate Impacts Group;

-- Part II – “Reservoir Operations Assessment – Reclamation Tributary Basins” (completed January 2011). Looks at potential climate change impacts to the USBR projects on the Yakima, Deschutes and upper Snake River subbasins, and

-- Part III – Reservoir Operations Assessment – Columbia Basin Flood Control 43 and Hydropower (completed June 2011). Makes projections of future reservoir elevations, outflows, power generation and spill for each of the climate change scenarios developed.


The three agencies recently completed a draft report entitled the Draft Climate and Hydrology Datasets for Use in the River Management Joint Operating Committee Agencies’ Longer-Term Planning Studies – Part IV Summary” that gives a synopsis of the findings of the three technical reports.


The report can be found at


The draft summary report has been released to the public for review and comments. Comments may be submitted to BPA at until close of business on Aug. 19.


The Corps and Bureau are the owners and operators of the 31 hydro projects on the Columbia and Snake rivers. BPA markets and distributes the power generated from these federal dams and from Columbia Generating Station. BPA also owns and operates about 75 percent of the Northwest's transmission system.


The dams and the electrical system are known as the Federal Columbia River Power System. Revenues collected through power rates cover the operation of these projects and the transmission system, the debt service required to repay the initial investment in the system, and contributes to other costs associated with these projects, such as the region's efforts to protect and rebuild fish and wildlife populations in the Columbia River basin.


According to a project fact sheet, the three federal agencies will integrate the new climate change data into their ongoing modeling and planning efforts on a number of topics including:


-- the Columbia River Treaty Review,

-- flood risk management,

-- future fish and wildlife program needs,

-- future biological opinions,

-- ESA and National Environmental Policy Act analyses,

-- asset planning for the federal hydro system,

-- future energy resource development needs,

-- water conservation studies and measures (such as piping canals) that leave more water in-stream for fish,

-- tributary and watershed habitat improvement projects.


Among the key findings:


-- Temperature: Northwest temperatures are expected to increase by 1 to 3 degrees F from 2010 to 2039 and by 2 to 5 degrees from 2030 to 2059.


-- Precipitation: Overall yearly precipitation changes in the study were minimal. However, some of the models showed large seasonal changes, including more extreme wet and dry periods, some wetter falls and winters, and some drier summers.


-- Snow pack: More winter precipitation would fall as rain instead of snow, producing more runoff in the winter, earlier runoff in the spring and less in the summer.


-- Annual water runoff: The January through April runoff volume is projected to exceed normal flows at The Dalles Dam by 20 to 85 percent. The June through August runoff varies between 65 and 95 percent of normal flows at The Dalles Dam. Normal flow, or the historical reference climate period, is the average of flows from 1970 to 1999. Higher January through April flows would generate more hydropower and produce more spill at most dams. Hydropower production would decline at the same time increased temperatures drive greater summer power use.


-- Flood risk management: Flood risk management procedures will need to anticipate that runoff may come weeks earlier, shifting the peak runoff from April through August to March through July. Earlier releases of water from reservoirs at the flood risk management projects may be needed to capture the early runoff. Impacts to the timing of federal hydro system operations could also impact other spring and summer objectives such as flows for fish.


-- Energy consumption: Higher temperatures in the summer will result in more energy use to cool homes and businesses. Warmer temperatures in the winter will reduce energy use for heating. BPA computed the estimated changes in energy consumption and determined that the demand for federal power from 2010 to 2039 showed increases of 1 to 3 percent in July and decreases of 3 to 4 percent in December.


-- Fish impacts: The increase in the January through April flows would result in higher generation and increased spill at most dams. The reduced flows during July and August may impact the federal agencies’ ability to meet future objectives, including flow management, intended to benefit salmon and steelhead and other fish stocks.


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