Our LakesLooks can be deceiving
Water shortage? Look at all that water!
With so many large lakes, how could we be short of water? Well, looks can be deceptive. Only the upper metre or two of lake water is replenished each year by stream flow, and much of that evaporates to the atmosphere. This thin layer is all that people and nature can use. If we withdraw more than that, the lake levels will start to fall. Imagine the impact on docks and marinas if the lakes fell to much lower levels. Be careful! We might 'mine' the lake.
Poorly flushed lakes
Most of our big lakes are composed of 'old' water. Scientists describe the lakes as 'poorly flushed' and estimate that water resides in Okanagan Lake about as long as an average human lifetime. This is because outflow from the lake is small relative to the volume of lake water. So we literally 'live with' whatever pollutants we put into the lakes.
A 'bank account' view of our lakes
Think of our lakes as a bank account. Lakes are big accounts, but nature's annual deposit is small. If our withdrawals exceed the deposit, we start drawing down the account. |
Waterscapes:
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