Water Clarity

Sand can have a negative impact on the water quality and overall health of the lake. 

Some of these effects are algae blooms, decrease in lake depth, fish habitat loss and decline in fish population.  

While sand is not the only cause of these problems, it is the easiest one to control – simply don’t put more of it into the lake.  

Here are some of the ways that beach sand harms the lake.

Silting.
Sand does not stay put. Every footstep on the beach pushes it downhill towards the water and it drifts with the current and wind. 

Sand leaves the beaches and flows with the water toward the middle. Exposed sand blows from one spot to another, moves with rain and snow melt winds up in unintended places.

Sand that doesn’t drift away eventually works its way into the lake bottom, but even though we may  not see it, it’s still in the lake.  

The sand we add contributes to silting-in, making the lake shallower. People react by adding more and more sand which is not allowed in Minnesota.

Shallow water is warmer, supports algae growth and is lower in oxygen, conditions that create fish kills. 

Silting is a geologic process that happens naturally over hundreds of years, adding beach sand to the natural sediment load hastens this aging process of turning lake into bog or swamp.

Water clarity.

Beach sand is different from native lake soil. Sand drifts easily in water, it clouds it, preventing UV light from disinfecting bacteria in the lake —  a natural process that is necessary for maintaining good water quality.  As rainwater and snowmelt run over the beach they pickup this silt, it goes into suspension in the lake, and can be transported significant distances. The smallest/lightest particles are the last to settle, and thus the first to be stirred up by aquatic animals, humans or even wind fetch induced currents or the annual temperature induced turnover. Reduced clarity correlates to reduced visibility, and a reduction in disinfection of pathogens by ultraviolet light and in studied cases, increases in presence of microbial pathogens. Decline in lake water clarity caused a noticeable decrease in the value of surrounding homes.

Biological Impact.

Deposited sand has major biological impacts on the lake ecology. Sand deposited and drifted along the shore and lake bottom can smother bottom-dwelling algae and invertebrates, reduce the amount of aquatic and shoreline habitat for fish and crayfish, destroy spawning and nesting sites for reptiles and amphibians, and disrupt the food chain. Fine sand particles suspended in clouded water may clog the gills of our lake fish that are not adapted to a sandy environment. This threatens the fish population.

Chemical Impact.

Beach sand may contain a number of contaminants that will wash into the lake water changing its natural chemistry.  If the sand contains phosphorus, a nutrient that supports plant growth and a major contributor to the decline of lake quality, it washes into the lake essentially fertilizing it.  One pound of phosphorus can produce tens of thousands of pounds of algae! As the lake becomes shallower from erosion and silting, there is less volume of water in which these toxins and other contaminants can be diluted.  Sand is not the only or largest source of contamination in the lake (bigger culprits are run-off from our septic systems, roads and lawns), but it contributes.

Options. 

There are alternatives to beach sand that cause less damage to the lake ecosystem and water quality. 

Check with the county for permits and advise on the best management practices.