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By Darrell Corkal, Prairie Farm Rehabilitation Administration, Saskatoon
In December 1993, a project aimed at developing economical options for improving the quality of surface water supplies in rural Saskatchewan was announced by the federal and provincial governments. Funded under the Agriculture Green Plan, the objectives of the four-year project are:1) To develop cost-effective and easily implemented methods to ensure drinking water in small rural reservoirs meets or exceeds current water quality standards. To achieve this goal, both safety and aesthetic factors must be improved.
2) To develop reservoir management techniques that will provide safe water for non-potable agricultural uses such as livestock watering.
At first glance, this may sound relatively easy to achieve. However, dugout water can contain compounds such as dissolved organics (some of which will discolour the water) in levels that can be 10 times higher than both Buffalo Pound (Regina's drinking supply) and the South Saskatchewan River (Saskatoon's supply). Quite simply, rural prairie water from ponds, dugouts and small reservoirs is amongst the most challenging in the world to treat for safe drinking water.
To help us work toward our goal, PFRA and the Saskatchewan Research Council have put together a network of agencies and people. This network includes the University of Saskatchewan (Civil and Chemical Engineering), Napier University (Scotland), the Saskatchewan Water Corporation, and the City of Saskatoon Water Treatment Plant. The effort also involves several private companies, including one manufacturer of dugout covers and one manufacturer of biofilm reactors.
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Under the Canada-Saskatchewan Agriculture Green Plan, we have also begun collaborating with several Saskatchewan ADD Boards. We are now monitoring and carrying out experiments on more than 50 locations across Saskatchewan (mostly private farms and a few small communities). We have carried out thousands of chemical analyses.
Highlights of our work to date include the implementation of several pilot water treatment systems throughout Saskatchewan. These treatment systems produce drinking and household water from poor quality surface water. The system consists of a large sand filter (around 1,000 L) and a biofilm reactor where dissolved organics are removed biologically. This water is then suitable for non-potable household use or can be further treated through reverse osmosis to obtain high quality drinking water.
No matter how good an in-house treatment system is, it is better to also manage the water source (the dugout), and the land draining into the dugout (the watershed). A critical component of our research is focused on managing water reservoirs. We have worked extensively on coagulation using aluminum and iron salts. These chemicals are commonly used in community water treatment plants, but we are trying to modify their application for direct use in reservoirs. To that end, numerous field experiments on dugout sites have been conducted.
We are also looking at reservoir management techniques using biological manipulation to encourage the growth of certain organisms which improve water quality. For example, by manipulating the nitrogen to phosphorus balance within the water, levels of future algae growth can be minimized. On-site dugout experiments with nitrogen manipulation have been completed with promising results.
Dugout management can also include the installation of covers, which act as a light barrier to prevent the growth of algae. An added benefit of the covers is reduced evapo-transpiration and lower summer water temperatures. Under this initiative, nine pilot sites have been physically modified with dugout covers to study the results.
To contact the author, write to PFRA, Box 908, Saskatoon, Sask., S7K 3M4.
