If the temporary base level is lowered a stream will attempt to adjust to lower its valley. In this photograph of the Snake River in Idaho you can see two terraces. The highest terrace is the oldest. Think about the history of this area as reflected by these features. Lacustrine - Lake Environments.
Lakes are rather ephemeral features.
Sedimentation acts to fill up the lake and the area may become swampy and then dry land over time. Aeolian - Wind Deposits. Shifting of river systems, advance and retreat of glaciers, the action of the wind, etc. The first deltas studied were deposited in fresh water lakes - Gilbert Deltas. When a stream actively deposits sediment in a lake the delta progrades and may eventually fill in the lake.