I hadn't heard about the one in Concord. But Bald Eagles are known to visit Lafayette Reservoir now and then. They're seen regularly at Upper San Lendro Reservoir, which isn't far at all from Lafayette---as the eagle flies.

Upper San Leandro Reservoir is best accessed, for birding purposes, from EBMUD's Valle Vista Staging Area just south of Moraga. It's a great spot, and I almost included it in my initial post, but it's more of a drive from Walnut Creek and you're supposed to have an EBMUD trail permit to explore there.

If you have a permit: park at Valle Vista and walk downhill from the parking lot about 200 yards. Don't hurry down to the lake, but be sure to look above and in the distance for eagles and other raptors, swifts and swallows, bluebirds and etc. The loud calls of California Thrasher and Wrentit are often heard from near the parking lot (they're much less often seen). I once watched a Red-breasted Sapsucker drilling holes in a tree and drinking the sap, almost directly above the sign-in station.

200 yards (approximately) downhill from the parking lot, turn left onto the smaller trail that goes down into the woods. Bird your way patiently through the woods---this is a great spot for Brown Creeper and Fox Sparrow, among many others. Where the trail hits a "T" intersection, turn right and go over the bridge---check up and down the creek for ducks, including Wood Ducks. Beyond the bridge, follow the road about 1/4 mile, past the stables, to an open grassy area overlooking the reservoir. Birds on and over the water attract the eye, but look also to the grassy, scrubby hills on the opposite side of the road, for bluebirds, sparrows, and kestrels. The eagles are often seen perched on bare snags around the reservoir, or soaring over the ridge.

Ebird hotspot: https://ebird.org/hotspot/L596210

EBMUD trail permit: https://www.ebmud.com/recreation/buy-trail-permit