Hydro in the Ninth District

Since 1999, the hydropower share of electricity production has generally declined in the district—by as much as a third in some states.

That is partly due to two reasons. First, hydropower has seen little expansion over the years, while energy production and consumption have risen significantly since 1999. Second, hydropower depends on river flows, and the years of drought in the Dakotas and Montana have had an impact on its production. That influence can be seen in 2010 figures, which increased dramatically in the Dakotas, taking advantage of a high-water year in the Missouri River basin.

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Hydropower’s share of a state’s electricity production is also a bit misleading because some states are major power exporters. South Dakota produces about three times the hydropower as its northern sibling, but hydropower’s share of state electricity production is more than 10 times higher (54 percent versus 4 percent, respectively). That’s because North Dakota’s vast coal reserves have made it a major producer (and exporter) of power.

The federal government defines energy in “megawatt hours,” or MWh. One MWh is 1 million watt hours.