Aquatic Habitat (aka Weeds) by Simon Lunn Parks Canada Agency
This article originally appeared in the Summer, 1999 issue of the Friends of the Rideau newsletter, The Rideau Ripple.
As most boaters and waterfront residents along the Rideau are well aware, 1998 was a banner year for the aggressive growth of aquatic plants and algal blooms. Eurasian Watermilfoil, a prolific submergent aquatic plant common to many North American waterways, was first introduced to the Rideau in the 1960's, and has since spread here to become a nuisance species, particularly in navigation channel areas.
In 1998, excessive growth of this plant (or "aquatic weed" as many regard it) showed up weeks earlier than normal in areas like the River Styx near Joyceville, and for the first real time, in the downtown cut in Ottawa. Neither Parks Canada nor the contractor (through no fault of his own!) we hired to mechanically harvest the vegetation in the main navigation channel were fully prepared for the impact of such early, sustained warm weather conditions. Combine this with unusually clear water conditions in the Ottawa Reach, waters high in nutrients, and the usual efforts to minimize in-water disturbance during fish spawning activity at this time of year- and voila!- a perfect opportunity for aggressive underwater plant growth! As a result, we were hard pressed to properly manage the aquatic plant growth in the usual 20 selected channel areas between Ottawa Locks and Kingston Mills, and especially in downtown Ottawa where explosive growth took place!
To help address some of these problems, Parks Canada has recently contracted the services of two companies to mechanically cut and harvest submerged aquatic vegetation along the Rideau Canal in 1999. Jeff Pitt of Elgin has a two year contract to clear 18 problem areas from Burritts Rapids to the River Styx. In response to another warm spring and some low water levels, emergency harvesting work was already started on Saturday of the May Long Weekend in the River Styx, to be followed up quickly by a visit to the area directly upstream of Burritts Rapids. Other areas may have to wait until late June-early July, once fish spawning activity subsides.
A second company, Aquasphere Technologies, from London, Ontario has been contracted to work exclusively in the downtown "Ottawa Reach" section of the canal, between Hartwells Lockstation and Ottawa Locks, including Dows Lake. One or two sessions of early-mid summer mechanical cutting and harvesting of the milfoil vegetation will be combined with use of other patented technology on a limited experimental basis later in the season. Emphasis will be placed on doing a better job at keeping the full navigation channel clear in the main cut as well as into Dows Lake, and cutting in other selected areas of particularly thick growth in the man-made "Ottawa Reach". It will be a bit of an ecological and aesthetics balancing act as we try to meet the needs of people and their recreational pursuits while maintaining newly developing habitats that are already supporting healthy populations of waterfowl and fish in the heart of the city.
In the meantime, since Rideau Canal policy no longer permits the use of chemicals (since about 1995) to control aquatic vegetation along the Rideau, waterfront residents should apply to the Parks Canada-Rideau Canal Office in Smiths Falls to obtain written approval to mechanically harvest submerged aquatic plants causing a serious problem (e.g. for boat access) in front of their property. For further information, call Jim Reynolds or Simon Lunn at (613) 283-5170.
UPDATE
For information about aquatic vegetation see the Managing Aquatic Vegetation Page in the local resident's section of this website
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