Young People Swimming in Pine Lake, ca 1940s |
-- Salvato, Nemerow, & Agardy, Environmental Engineering, John Wiley & Sons, 2003, p. 551
Dredging the Lake
The average lifespan of a man-made lake is about 75 years. During that time sediment carried in by the lake's headwaters slowly settles on the lake bottom, making it more and more shallow. As the lake's depth increases the temperature decreases; this leads to increased algal and bacterial growth which can pose a hazard to swimmers and fishermen. Eventually the lake will fill with no longer be a lake.
Our lake was created in the mid-1930s-- 75 or so years ago. The eastern portion was purposefully shallow, the western portion less so. Snapfinger Creek apparently fed directly into the lake-- along with all its silt. At some point-- I believe it was the early 1940's-- the city created a berm along the south side of the lake, creating a separate channel for Snapfinger and a flume for inflow into the lake.This certainly reduced sedimentation, but by the beginning of the twenty-first century the lake was moving inexorably toward eutrophy. The lake had become warmer as it had grown more shallow, and bacterial counts often precluded swimming.
The solution to this problem is, clearly, dredging-- draining the water from the lake, removing accumulated silt and hopefully making the lake a bit deeper than it was originally, rebuilding the berm along the south side of the lake, refilling the lake, and restocking it with native fish.
Happily, this is about to happen.
In future posts I'll write more about this project and document its progress with photos.
No comments:
Post a Comment
Note: Only a member of this blog may post a comment.