What Farmers Think About Their Water

by Hans Peterson, Saskatchewan Research Council, Saskatoon, Saskatchewan

Hans Peterson studies control and pesticide toxicity to improve water quality in farm ponds and dugouts

In February, 1987 the Saskatchewan Research Council (SRC) sent out a questionnaire to 105 farmers about their dugout drinking water Eighty-one of these questionnaires were returned with a bottle of water which was analysed by SRC. The responses were sometimes difficult to interpret, but the highlights are reported below. This study was funded by the Saskatchewan Agriculture Development Fund.

The chemical composition of these dugouts were determined by SRC and is shown in the table below.

This shows that the average pH is high, but acceptable. The average level of total dissolved solids (TDS) is suitable for drinking with only a few having levels above the level considered unacceptable (500 mg/L). The magnesium levels indicate that hardness should not be a concern and softening of dugout water is not necessary. The copper levels are high with only copper tolerant organisms being able to survive. The phosphorous levels are sufficiently high to form large algal blooms. The nitrogen content in the dugouts will support the major copper tolerant organisms, the green algae.

The two major problems for maintaining drinking water from dugouts were algae (94%) and weeds (75%). All other problems mentioned (12 categories) amounted only to an average of 5% per category. The problems were considered moderate to severe in 72% of the cases with 26% having low to occasional problems.

Odour was considered a problem by 76% of the respondents and taste was a problem for 58%. Forty-four percent considered this odour to be grassy and 38% described it as rotten eggs. The grassy odour is caused by algae and the rotten egg odour is caused by a lack of oxygen. Aeration will prevent the rotten egg odour and algae control will prevent the grassy odours. Less than a teaspoon of some taste and odour producing compounds produced by the blue-green algae is sufficient to make a dugout smell. This situation will also make the water taste bad.

The problems were recent for 47% (0-5 years) and 38% have had the problems for more than 6 years. The problems were most severe between June - September (5 1 %) with 26% having problems from January to May and 23% having problems from October to December. Forty-five percent had problems filtering the water with 48% getting their filters clogged monthly and 52% at intervals longer than one month. Only 17% of the respondents chlorinated their tapwater.

Ninety-eight percent of the respondents have treated their dugout to reduce the above problems. The major treatments were copper sulphate (bluestone, 94%), aeration (73%), diquat (Reglone A, 43%), pond aid (27%), chlorine (15%), aluminum sulphate (alum, 11%), potassium permanganate (10%). In addition, the use of pesticides that should not come in contact with drinking water was reported. Included among these were: paraquat, simazine, acrolein, and amitrole.

Copper was used most extensively and a comparison of the responses were divided into Good control of algae with copper; Poor control of algae with copper; Fairly good control of algae with copper; Not too good control with copper: It was found that the two extreme categories, Good control vs. Poor control, were reported an equal number of times, 28% each. Several respondents commented that treatments used to be effective, but not in the last couple of years. Copper treatments appear to have worked in several cases with quite low doses of copper. The use of such low doses were often due to stocking the dugout with trout. In other cases extremely high doses had been used.

Maintaining dugout water at extreme conditions of pH, copper sulphate, chlorine, diquat, aluminum sulphate, potassium permanganate, etc. will produce an appearance of good quality water because there is little or no biological activity after treatment. When such conditions retum to levels that are physiologically acceptable for the most tolerant organisms, which often are fastgrowing phytoplanktonic green algae, the water quality will degrade to make it virtually unusable as a water supply.