I sought and found such a place not far from Bangor, just below the Veazie dam. I obtained permission to set up a blind - essential for not scaring off the birds. Once I had my spot, it still wasn't so easy. Remember that it's vital not to harass these birds. During the winter, wildlife needs to maintain energy reserves for survival.
Wasted effort fleeing enough human encounters can mean death for a bald eagle.
I had to be in the blind before dawn when the eagles came down river to perch in tall white pines across the way. Then I had to wait until they moved on, sometimes watching them for hours without one ever coming close enough to fire a single frame of photography. Anyone pursuing wildlife photography in winter really needs to understand the survival needs of their subjects. A Nicad battery in the camera or a separate battery pack or spares in a warm pocket are essential to keep a modern camera operating when it's below zero. Film should be rewound slowly, preferably by hand, to prevent tearing the brittle stuff or the possibility that static electric sparks will imprint on the film.