Where does the pollution go in lakes from speedboats?

The oils and hydrocarbons from the gasoline engines that spill into the water pollute the lake. Almost all lakes have a stream that enters it and one that flows out. Thus there's a limiting effect to how polluted it gets, as some of the pollutant flows out through the outflow stream.

If there's no outflow, the concentration of pollutant never diminishes. But even then some -- not much -- pollutant is eliminated by (1) sinking into sediment, (2) broken down by bacteria, or (3) absorbed by fish which may be removed by fishermen or predators.

I've never heard of solar-powered pleasure watercraft.

The pollution usually comes from the exhaust of the watercraft. This is a mixture of burnt gas and oil from the motor. Most of the older watercraft had 2 stoke motors that you mixed oil and gas together in and used it as a fuel. The oil was for lubrication of the motor. Today we have 4 stoke motors which are more environmentally sound but they still pollute. As for where the pollution goes in the lake, air, and even land. It is air born usually when it comes from the watercraft and this air born pollution will settle on the surface they oil eventually mixes with the water and come in contact with the land.

As for solar boats I do not know of any commercially available but I have read about some people who take pontoon boats and put solar on them. They are slow and have limited daily range are not performance by any standard but can be fun.

2 places:

1) The air

2) The lake

if we had a solar powered watercraft, that would be an end to alot of pollution in the water.

Into the water, plants and soil that surrounds the lakes. It can also be ingested and absorbed by people and animals. Gross but true.

It goes into fish, and the into you if you eat fish. Think about that next time you're chowing down on some nice bass.

the polution ends up on the bottom and on the edges of the lakes

and if it flows out it goes on to polute other places