Ornamental lakes were hugely popular features in grand Victorian gardens. At the beginning of the period, they tended to be highly formal, drawing on the symmetrical, balustraded Italian style. As the impact of industrialization deepened, however, there developed a desire for more natural gardens, a trend pioneered by the Irish gardener and writer William Robinson. From the description, it seems that whoever laid out the lake at Bly was ahead of the times in favouring a comparatively ‘wild’ aesthetic.
British readers can find near-by Victorian gardens run by the National Trust here.