Shoreland Protection Rules

[Gavia immer]

Originally Posted by Pineedles

Our shoreline is lined with huge granite boulders of various shapes and sizes and frankly looking at pictures taken over 100 years ago there has been no erosion.

I'd need to check with DES, but geologically speaking, it's only recently that the lake has been managed to limit damage from winter's ice. For 10,000 unmanaged years, the lake's level has seen many extremes.

I can see where thousands of years of high winter ice allowed the pressure of ice expansion to move boulders into an ancient shoreline. It would be the most extreme of those expansions that made the shoreline of "just" 100 years ago.

Ancient forest fires, modern clear cutting, and the subsidence that resulted has allowed much sand and soil to be washed through that border of boulders. The land erosion you are witnessing would be wave action pulling nutrient-rich soil out from behind those original boulders. Runoff from impervious surfaces speeds the erosion.

Depending on exposure and rock ledge borders, shorelines that have limited wave action often have the steepest slopes. Winni's lakefront lots and shallows would generally be even steeper if it wasn't for erosion. That said, I'd ask "shore things" to correct any of my assumptions.

[Orion]

Originally Posted by Gavia immer

I'd need to check with DES, but geologically speaking, it's only recently that the lake has been managed to limit damage from winter's ice. For 10,000 unmanaged years, the lake's level has seen many extremes.

I believe before the dam was built, the lake probably maintained a more consistent level, within a foot or so of the natural spillway. There were, of course, a few major geological events (such as earth surface shifts that changed the lake's outflow from Alton to Laconia) but aside from that, the levels were consistent for a long time. The dam allows a much wider range of level control, to include winter drawdown.

Originally Posted by Gavia immer

I can see where thousands of years of high winter ice allowed the pressure of ice expansion to move boulders into an ancient shoreline. It would be the most extreme of those expansions that made the shoreline of "just" 100 years ago.

Actually, the opposite is true. The natural wave action around the lake eroded the soil between and around the rocks exposing the granite. Where there are larger wave forces, the shoreline is more rocky. This also one of the reasons why the lake tends to be so clear since there is less suspended sediment from erosion. Ice does move the rocks around a bit, but if anything, it would tend to continue breaking up the shorline (over millenia) and decompose the rocks into sand into the lake.