Boraginaceae, the borage family.
Plant: Robust, hairy, branching plant 1'-2', with tight hanging clusters of blue or sometimes pinkish, bell-shaped flowers. Perennial
Flowers: Blue to pinkish, narrowly bell-shaped, about 1/2"long, with five shallow lobes and five sepals. The slender pistil protrudes well beyond the corrolla lobes. The flowers are arranged in a tight, uncoiling cluster - a raceme.
Leaves: Alternate, ovate, to 4"-6", very hairy below, with a short stalk (petiol) often winged.
Fruit: Separating into four hard, seed-like segments.
Habitat: Clearings, forest boundaries.
I'm not entirely sure what Merensia species is pictured here.
M. virginica, Virginia Bluebells, the common native species in this area
has smooth leaves and stems and larger flowers; this plant is extremely rough and hairy.
It most closely matches the description of M. paniculata commonly known as Northern
or Tall Bluebells, which is native to the US, but not to this area.
The plant is almost certainly a garden escape, and may be derived from a commercial cultivar.
Where to find it:
A single location on the north shore of the large pool north of the main pond.