5.2. SR 10-04-2004
Item 5.2.
MEMORANDUM
TO: Mayor and City Council
FROM: Rebecca Haug, Environmental Technician
DATE: October 4, 2004
SUBJECT: Consider Curlyleaf Pond Weed Remediation in Lake Orono
On October 20, 2003, the Elk River City Council approved a drawdown of Lake Orono
to help eradicate curlyleaf pond weed which had proliferated in the lake. This is a non-
native invasive species that can clog shallow areas of waterways if not controlled.
According to Wendy Crowell, Aquatic Biologist, Exotic Species Program, Department
of Natural Resources (DNR), the drawdown did reduce the abundance of the curly leaf
pondweed; however, temperatures were not as cooperative causing several curly leaf
pondweed plants to survive the drawdown. At the August 18, 2004 Lake Orono Water
Quality Task Force Meeting, it was discussed that another drawdown could reduce the
abundance even more. City Staff has discussed this with DNR Waters, Fisheries and
Aquatic Plant representatives and none of them had concerns with another drawdown.
The drawdown would be done the same way it was last year. It is proposed to start on
November I, 2004 with a gradual four-foot drawdown of the lake (approximately over a
one-week period), allowing the lake sediment to dry (approximately one week
depending on weather) and having cold temperatures to freeze the plant bulbs that are
contained in the sediment of the lake (approximately ten days). The lake will then be
refilled gradually (approximately over a one-week period). If temperatures are
cooperative, the drawdown is proposed to only last one month. DNR Fisheries will
determine if the lake needs to be refilled sooner if there is a threat of a fish-kill.
The public will be notified of the drawdown through the City's website, The Current, the
Elk River Star News and the Lake Orono Improvement Association flyer sent to all lake
shore owners. Anyone wishing work along their shoreline other than general cleanup,
will need to contact the Building and Environmental Department to make sure their
project conforms with shore land regulations.
Staff has discussed this with both Elk River Municipal Utilities and the Street
Department. The cost for this remediation is $0.