This is the third in a series of articles on project priorities from the Dunlap Lake 20-Year Master Plan. It has been recommended that the Association build a catch basin with berms to slow down the flow of incoming water and allow sediment to drop out of the water before it flows into the main part of the lake.
Sediment from upstream (siltation) has been filling the lake’s coves unchecked for several years. This is most visible at the south end, where two major creeks drain almost 70% of our watershed into the lake.
The silt retention basin built in 2009, following a major washout of the bridge on East Lake Drive, has almost fully silted in. Other sections of the lake continue to accumulate material from other smaller tributaries and shoreline erosion. The shallow waters contribute to algae growth and other water quality issues. DLPOA has worked with the Army Corps of Engineers and Engineering firm Horner Shifrin to come up with a plan that addresses these issues.
The plan allows us to remove material from the lake in multiple phases and trap more silt in the retention basin. Engineers recommend a first phase that would expand the south-end silt retention basin and build a berm and weir structure that would slow water flow into the lake in most rain conditions, and allow the silt to “drop” out of the flow into the basin before it enters the main part of the lake. The plan would capture up to 60% of the “silt” in this area (reducing future removal costs) and still allow boat traffic into the southernmost area of the lake. The plan would include a regularly-scheduled clean out of the basin to keep it operating efficiently.
An engineer’s drawing of the preferred option for the sediment basin is shown above. The red checkmarks indicate where additional association land could be removed to expand the capacity of the basin.
Ask questions at www.dunlaplake.org/vote/ or join the Zoom Q&A at 7 p.m. Monday, April 12. A zoom link will be mailed to this e-mail address the day of the event. Contact Carolyn Green at 791-1398 If you don’t have it by 2 p.m.