Abstract:
Stormwater ponds are often assumed to be well-mixed reactors. To better
understand the water quality of stormwater ponds, the seasonal and diel water quality
patterns of the Potomac Science Center stormwater pond were discerned using weekly
depth profiles, continuous monitors, light profiles, and local weather stations from July
through October of 2020. Water samples were also collected for analysis of total
suspended solids, in situ chlorophyll a, and phytoplankton taxa. Results indicated the
pond experienced summer stratification driven by air temperature and solar radiation.
For the period July 24 through August 29, biological processes drove the water quality of
the pond’s 10-day stable periods, which were disrupted by three mixing events. No
surface HABs were observed, but the lower layers of the pond experienced hypoxia and a
HAB. Ultimately, the pond performs its intended function: to allow the settling of
organic matter to the bottom layers so the surface waters maintain good water quality.
