Green infrastructure mitigates severity of flooding events on the State University of New York at (SUNY) New Paltz campus

Background/Question/Methods Increased frequency and severity of storms due to climate change will directly affect
biogeochemical cycles within aquatic ecosystems in the eastern US. Anthropogenically
impacted watersheds, like the Saw Mill Brook watershed in New York, are highly
susceptible to large storms. The watershed encompasses the SUNY New Paltz campus
where we are collaborating with the facilities department to promote infrastructure that
will allow our watershed to be more resilient after large storm events. We sought to
investigate water quality changes within our subwatershed
to the Hudson Valley by
monitoring water quality throughout the summers of 2013 and 2014 to determine how
an ecosystem comprised of a series of ponds on our campus responded to storm
events. We compared infiltration rates of different land surfaces including a vegetated
bioswale, impervious asphalt and porous blacktop parking lot. Monitoring occurred at
several temporal scales including weekly sampling for biological and chemical
parameters and high frequency measurements of water quality parameters using an
automated buoy with dissolved oxygen, conductivity, and turbidity environmental
sensors. Additionally, in the summer of 2013 copper sulfate was sprayed twice, acting
as an herbicide to sink algal biomass to the bottom of the ponds for aesthetic reasons.
The consequent summer no copper sulfate was sprayed; however, algal biomass was
periodically manually removed from the ponds and composted.

Results/Conclusions We found that storms affect water quality in different ways. High frequency data
collected from the sensor data of the buoy allowed us to watch water quality impacts
from storm events. Land use distribution on our campus dictates infiltration rates of
stormwater entering the watershed. Infiltration of the porous parking lot was 24 times as
efficient at recharging groundwater than the impervious lot which made rainfall a source
of overland flow into the ponds. Following storms, dilution in the pond caused baseflow
conductivity levels to decrease by half and fecal coliform bacterial densities to decrease;
erosion caused sediment to enter and consequently turbidity increased four fold from
baseflow measurements. Additionally, total phosphorus increased resulting in an algal
bloom with highly variable dissolved oxygen fluctuations. Composting algal biomass in
the series of ponds lowered algal biomass compared to months when copper sulfate
was sprayed on the surface of the ponds.This data will provide the baseline as SUNY
New Paltz implements campus wide green infrastructure practices such as vegetated
bioswales, rain gardens, and permeable pavement parking to alleviate these storm
related water quantity and quality issues.