WAPA - Western Area Power Administration

02/14/2018 | Press release | Distributed by Public on 02/14/2018 15:10

​Summarizing Water Year 2017 hydrology conditions​

Editor's Note: The following report summarizes Fiscal Year 2017 data from the WAPA Hydropower Conditions webpage for straight power purchase costs, which are based solely upon hydrology, actual hydropower generation and related generation shortages. Readers may review all data by visiting wapa.gov, Power Marketing, Hydropower Conditions.

One of the biggest challenges for hydropower is water variability due to intermittent drought and flooding. By definition, hydropower needs water to generate electricity. Without it, WAPA must buy power on the open market from other sources to meet contractual obligations to its customers. This is referred to as purchase power.

In an ideal year, snowpack around the West is average or above average, yielding snowmelt runoff to recharge reservoirs behind the dams and powerplants that provide the energy WAPA markets. Federal dam owners like the Bureau of Reclamation, the Army Corps of Engineers and the International Boundary and Water Commission move water to federal hydroelectric powerplants.

WAPA markets the subsequent power generated more than 700 preference customers. Its customers, in turn, sell that power to about 40 million Americans.

Water around WAPA in 2017

WAPA's actual generation was 101 percent of average in Water Year 2017, for a total generation of 26,148 gigawatt-hours.

For the same period, total purchased power was 2,638 GWh with actual purchase power expenses of $64,687,868, which equates to $24.51 per megawatt-hour.

The Colorado River Storage Project Management Center projected most probable purchase power expenses for Water Year 2017 to be $11,688,670. Actual purchase power expenses were higher, at $12,200,933. The cost per MWh was $24.16. Lake Powell ended the water year at around 60 percent of capacity with an elevation of 3,628, which is about 138 feet above the minimum generation level. Throughout the fiscal year it held relatively steady between 46 and 63 percent of capacity.

Desert Southwest's hydrology is mostly dependent on the Colorado River Basin snowpack and precipitation above Lake Powell. The Water Year 2017 precipitation was 81 percent of average. The region's most probable projected purchase power expenses were $8,527,308. Actual purchase power expenses were higher, at $9,686,758, with a cost per MWh of $44.29. Lake Mead ended the fiscal year with an elevation of 1,082 feet, about 132 feet above the minimum generation level. Throughout the water year it fluctuated between 31 and 135 feet above the minimum generation level.

In Rocky Mountain, the overall reservoir content at the end of September was 83.5 percent of average. The overall reservoir content peaked in February at 126 percent of average. The Loveland Area Projects area remains mostly drought free, but the trend is for drier conditions in some areas. The Water Year 2017 reservoir content at the end of September was 83.5 percent of average. The most probable projected purchase power expenses were $12,537,488, but actual purchase power expenses were significantly lower, at $8,314,367. The cost per MWh was $37.50.

In Sierra Nevada as of Sept. 30, cumulative precipitation of the Northern Sierra Eight Station Index was at 186 percent of average for the date. Accumulated inflow for the water year was 171 percent of the 15-year average for Trinity, 181 percent for Shasta, 281 percent for Folsom, and 271 percent for New Melones. Reservoir storage as of the same date was 125 percent of the 15-year average for Trinity, 138 percent for Shasta, 142 percent for Folsom, and 158 percent for New Melones. The region began Water Year 2017 with a most probable projection of purchase power of $8,093,706 and ended at $10,918,440. The cost per MWh was $24.91.

In Upper Great Plains, runoff in the Fort Peck and Garrison reaches was below average due to continued drought conditions, but runoff in the lower four reaches was above average. In Montana, 86 percent of the state is impacted by drought, with the most severe conditions present over the northeastern quarter of the state. In North Dakota, 63 percent of the state is impacted by drought. In South Dakota, 59 percent of the state is impacted by drought. The water year ended with the active conservation pools for the Canyon Ferry and Yellowtail dams were 81.9 percent and 99.2 percent full, respectively. UGP's most probable projection for purchase power was $31,636,163. Actual purchase power expenses were lower at $28,072,390. The cost per MWh was $20.28.

Anticipating upcoming water year

The Seasonal Drought Outlook provided by the National Weather Service's Climate Prediction Center in November 2017 showed that drought development is likely throughout much of the southern United States. Drought is also anticipated to persist throughout many areas in the southern United States and several northern states.

Drought removal or improvement is expected in western Montana, however. Eastern Montana, North Dakota and South Dakota are expected to receive above-normal precipitation this winter, but this is not expected to be enough to overcome existing drought conditions.

Dryness and drought have decreased in coverage over the Midwestern states during the past month, with the exception of Missouri, where moderate to severe drought covers most of the southeastern half of the state. Prospects for improvement and removal of drought are best for the northern and eastern portions of Missouri.

Elsewhere across the Midwest, drought removal or improvement is expected. A comparison of the latest drought conditions with those from a month ago across the High Plains region reveals relatively small changes overall, especially in terms of spatial coverage.