Lake Ellyn Park 2013 Master Plan

2. site analysis & existing conditions
event. Recommended improvements included lowering
the lake level by six inches, increasing the discharge rate
to the maximum allowable under the DuPage County
stormwater ordinance, and modifying the outlet structure
to allow greater discharge during smaller events. None of
the proposed improvements would prevent flooding of
Duchon Field during large events. However, the proposed
improvements would reduce the potential flooding of the
boathouse.
A bypass pipe was installed in 2005 to allow the lake to
freeze in the winter months to allow skating on the lake.
Today, virtually all the runoff entering Lake Ellyn
originates from the roofs, lawns, and streets within the
watershed drainage area of the lake. This runoff contains
heavy metals, petroleum based hydrocarbons, salt, and
other automobile related pollutants from the streets as
well as fertilizers and pesticides that run off from lawns.
Urban runoff also typically includes salt from winter
deicing, which impacts water quality. However, the bypass
pipe that was installed to reduce water movement in the
lake to allow for wintertime freezing routes runoff straight
from the inflow structures to the outflow structure during
winter months, bypassing the lake, and reducing the
amount of salt directly entering the lake.
To address the other urban pollutants, particularly
the nutrients in fertilizers that result in algae blooms,
a number of features are proposed as discussed in a
subsequent section. These features include aquatic plant
material to utilize the nutrients, reducing their availability
to grow algae.
Lake Ellyn is excavated in 2005 to install a bypass pipe
flooding overtops the dam in a large storm event in 2008
inflow structure on the south side of Lake Ellyn
20 Glen Ellyn Park District