Switching back to lake water
 

My cottage has gotten its water from the lake for years with no issues. This summer I decided to tap into the seasonal town water. I switched back today in anticipation of seasonal being shut off and the water is very dark and dirty. Any suggestions? I am thinking the intake became covered with silt while sitting unused all summer. Will I need to flush the hot water heater?
Also wondering if the shallow water level will cause intake to freeze. Its less than a foot deep where it enters lake.

yes it will freeze
 

When the Lake freezes down to the level of your line, you line will freeze as well. The ice can get 3-4 ft thick in some areas, so it's inevitable. Right now the water temp is still pretty warm, so if you're not staying all winter, you should be OK until there is a good amount of ice on the lake. There are heating wires you can have installed in your line to prevent freezing, but if the intake is not below ice thickness level, it won't work all winter. Also, the line running to the house needs to be deep enough underground to prevent it from freezing as well, which can happen if the air temps get cold enough.

If the line has been sitting idle in the water for an extended period, it will form scum on the inside of the line and will have to be flushed out, along with the hot water heater, if the water brown water has been run into it.