I saw a pair of Barrow's Goldeneyes today (Saturday) on the Mississippi River at the Coon Rapids Dam. They were on the east side of the river, south of the main entrance to the park. They were near the bend in the river close to the north end of Cenaiko Lake. There are two parking lots near there and a plowed trail that leads to the river where there is a snow-covered observation deck. The goldeneyes were close to the observation deck, and there were only about 25 goldneyes in total on the water. The female Barrow's stood out almost more than the male because of her bright orange bill. The male and female stuck close together.
Technically you need a park sticker to enter the park, but I don't know how strictly they enforce the requirement this time of year. They accept Anoka/Washington/Carver park stickers.