A view of Mirror Lake. (Peter Morenus/UConn photo)
The University of Connecticut (UConn) in Storrs is redesigning its project to improve Mirror Lake to address flooding and stormwater runoff concerns, holding off for now on dredging efforts that the college had planned to deepen the lake by removing decades' worth of built-up muck.
The UConn Board of Trustees earlier in May approved funding to revise the project's design, which will entail improvements determined in consultation with the Connecticut Department of Energy and Environmental Protection (DEEP).
UConn Today, the university's news service, said engineers will focus on two safety and compliance elements: improvements and/or repairs to Mirror Lake's dam and spillway, which pose flooding hazards during heavy rain; and stormwater control and water quality improvements associated with construction of the nearby South Campus Residence Hall and related infrastructure work.
Mirror Lake is visibly shallow, murky and weedy during many periods of the year, and has accumulated several feet of organic muck and sediment from the 50 years of development nearby, both from on- and off-campus projects.
Additionally, stormwater runoff from the lake's 165-acre Roberts Brook watershed, which includes non-UConn property, has flowed toward the lower-lying pond for nearly a century, impacting water quality and increasing Mirror Lake's volume.
The university originally had planned to dredge the lake, as well, to help maintain its existing footprint during storm events and reduce the need to increase the height of the dam – something necessary for flood control and dam safety. However, UConn decided to reduce the scope of work amid its campus-wide budget constraints.
The work is expected to begin in August 2024 once the design, permitting and construction bidding processes are complete, and to conclude all work within about a year, UConn Today noted May 5.
After 100 Years, Mirror Lake Still Has Issues
Unlike the university's Swan Lake to the north, Mirror Lake is not a natural water body. Instead, it originally was a marshy meadow just off campus when UConn began as the Storrs Agricultural School in 1881, and later became part of the institution's property.
By 1910, landscape architects already were proposing turning it into a human-made lake, both as an aesthetic feature and landmark of the central campus, and to find a proper use for the otherwise swampy, insect-friendly marsh.
Around 1922, the wooden dam on the marsh's northern side was removed, a new soil dam was created, and about four acres were flooded to create Mirror Lake. It was fully dredged in 1946 and partially again in 1970, but sediment from stormwater runoff has continued to make it shallower. In addition, goose, gull and duck excrement, along with other pollutants, have affected the water's quality.
Currently, UConn conducts annual maintenance programs, including cleaning and treatments, to combat algae growth. The addition of two fountains has also helped mitigate some of the algae blooms, although they are currently inoperable because their electrical connection is sourced near the adjacent fire-damaged Whitney House.
But Mirror Lake's capacity has been so greatly reduced by sediment, UConn Today reported, that during heavy rainfalls, water occasionally flows over the banks of the brook originating at the dam's spillway, becoming temporarily impounded at downstream culverts.
UConn Now in Charge of the Lake's Dam
The university took over dam inspection and assessment processes in 2016 from DEEP due to changes to Connecticut dam safety regulations.
After UConn's 2019 assessment, Mirror Lake's dam was determined to be an even higher danger than before and was moved into a hazard class defined by DEEP in which failure would result in probable life/safety issues and likely to cause problems along Connecticut Route 195, secondary roads and other downstream impacts.
As a result, UConn now conducts regular maintenance, including temporary repairs enacted in 2020 to the dam's spillway and surrounding area.
The planned work at Mirror Lake will likely help resolve the flooding issues, although university officials acknowledge dredging and site improvements that were planned around the pond will need to be revisited when capital budget funding allows it.
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