Just looked up something on MDU's site and made my way over here: www.montana-dakota.com/safety-education/powerline-safety - I know EXACTLY where that is because of that water tower. It's actually behind MDU's headquarters campus - the line was a 115kV/41.6kV double circuit (it originally was a double 41.6kV line but it was rebuilt in the very early 1980s).

That must have been quite the light show (and outage) when that happened. This segment of 41.6kV has only 1 source (and it now serves just one substation) - and it was no more than 2-3 poles to the right.