Nurture v. nature: managing the MIssissippi

0

by Trish Dyer

The Mississippi River does not spring forth from the centre of the earth.

And her waters are not infinite.

The fact is that, without human intervention, entire stretches of the River between Carleton Place and Pakenham would dry up completely during the heat of summer.  

She’s long, the Mississippi (212 kilometres) and she collects water from over 250 lakes, major river systems, creeks and streams along her length: forming lakes and tumbling down spectacular waterfalls before draining into the Ottawa.

In fact, geographers seldom refer to the Mississippi as a River. In her role as a drain for an entire complex of other inland bodies of water, the Mississippi is elevated to the status of a watershed: as in Mississippi River Watershed.

However, lakes, rivers, creeks aside, the Mississippi River Watershed (which covers  4.450 square kilometers of Eastern Ontario )  has some challenges. Aside from constantly draining into the Ottawa River below us, water surfaces throughout the watershed are subject to (incredible) water loss through surface evaporation and transpiration (through thousands of kilometers of shorelines). And it’s only sources of ‘new’ water to replace those losses are snowmelt and rain.

Indeed, annual records of water-in (precipitation) versus water loss (see Millstone: Tales of the Riverbank) show the entire system relies on a foot of water, more or less, to exist from year to year.

Our aboriginal predecessors accepted the Mississippi as is.

The River’s shores made ideal camping grounds during snowmelt and spring rains, when she ran high and fast, teeming with fish, a magnet for wildlife. However, as May turned to June and her waters grew lower, slower and warmer, they broke camp and paddled down or upstream to the deep colder waters of lakes to fish bass, lake trout and pickerel and hunt attendant wildlife.

Our European forefathers were not nearly as sanguine.

Lumber barons searching out ship worthy timbers for the burgeoning British fleet in the early 1800’s were impressed by vast stands of virgin pine, spruce and other species lining the Mississippi shoreline and by our cold and long winters, ideal for felling and hauling logs out of the bush to the water’s edge. However, they were almost as dismayed to learn that there was scarcely time for a single log run down to the Ottawa, before the River subsided.
Initially, they made do.  Water powered lumber mills sprung up below falls and rapids to saw stranded left over and logs from Dalhousie Lake to Pakenham, grist mills matched them across the River at Almonte and Carleton Place, textile mills sprung up at Almonte and Appleton.  But by the 1860’s they’d hit upon a partial solution.

By driving pairs of pegs into the riverbed at the narrow outlets of upstream lakes, including a cluster of finger lakes, and settling logs into them they formed a series of rudimentary dams at Crotch, Big Gull and Kashwakamak Lakes (near Cloyne) and Mississippi Lake ( behind present day Carleton Place Town Hall).

In fact, the system worked so well, that much of it remains in place today: between Upper Mazinaw Lake and the village of Lanark water levels at five descending lakes,Mazinaw, Shabomeka, Kashwakamek, Mississagogon and Big Gull are deliberately lowered each fall (by Mississippi Valley Conservation Authority) upstream of Crotch Lake to accommodate snowmelt and spring rain. If they were not lowered, Crotch Lake ( a semi-reservoir which is also ‘drawn down’ or lowered several feet each fall) would spill over High Falls and flood Dalhousie Lake, Ferguson Falls, Innisville, Mississippi Lake, Carleton Place, Appleton, portions of Almonte and all points in between. The partial dam at Carleton Place, on the other hand, is used during the summer to ‘augment’ low flow (keep water) from flowing out of Mississippi Lake.

Contrary to myth, none of those structures are capable of slowing the River’s flow. However, lack of water, increasingly pronounced droughts and downpours and changing patterns of precipitation (more rain during the fall in particular) are affecting it- making watershed management more and more challenging.

Downstream communities (including Carleton Place) which rely on the Mississippi for drinking water, require flow sufficient to keep the river running clean. And ever increasing numbers of year-round residents on Dalhousie and Mississippi Lakes, to name just two, want enough water at their end to enjoy their properties.

The provincial Lakes and Rivers Act, on the other hand, requires specific flows and levels at certain times of year at the upstream, the top end of the river, to protect fish and wildlife (lake trout spawning in the upper Lakes in September, for instance, require cold, deep water).