2.2. Water Table Changes

Long ago mature forests covered the watersheds. The story of how forests soak up snowmelt and rainfall can be complicated to explain. Forests catch and use water to live and grow. They also provide uneven ground that slows flows and a climate for soils under them with a shady environment sheltered from prevailing winds all of which encourage the water to soak into the soils rather than run off. For these and other reasons forests tend to retain water in the soil after rainstorms. This sponge-like ability to hold and gradually release water helps to ensure that the roots of trees have adequate water supplies and the streams have a good base flow of water.
 

A stream is only as healthy or clean as the valley through which it flows.
Extensive use of the valley without regard for the stream will quickly spell the end of a cold water (and sometimes a warm water) fish community and affect many other forms of life.

Forests harvesting, agriculture or urban and rural development, in short our land use practices change the runoff patterns increasing the quick and erosive surface flows and decreasing how much soak into the ground. This can change low flow summer and winter habitats for fish. Water running off cleared land peaks quickly, disappears downstream, and tends to be warmer. Humans add to this effect by filling in swamps and marshes, digging tile drains into once-moist fields, creating road ditches, and installing storm sewers that "quick-charge" our watercourses. What is the result of all this activity? When it rains, there is an erosive flush of high water over the land and into rivers. Shortly after, water tables quickly lower in the soils and our watercourses wither in dry summer heat.

The "Global Climate Change Effect" of warmer climate has resulted in shorter more intense summer rainfall, which combined with our poor land use and physically degraded streams, to produce even lower water tables and low stream flows in Nova Scotia. The worst droughts in recorded history have become progressively worse in the 1980's, 1990's and 2000's. Compared to the past, our summer habitats for freshwater fish are warm and drying up and in the frozen winter we have low flows that weaken over winter habitats.

.