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Continued urban growth and the related demand for water services such as water supply, wastewater treatment, and drainage pose a considerable challenge.

All the urban centres in the basin provide treated water and some level of wastewater treatment to household, industrial, commercial, and institutional users. The cost of providing these services is recovered through water charges and municipal taxes.

Two of the key challenges for the Saskatchewan River Sub-Basin (SSRSB) are providing safe drinking water and reducing effects of wastewater effluents on downstream communities and ecosystems.

Read more… about water and wastewater treatment in Medicine Hat

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Water Supply

Almost all the water used in the cities of the basin is surface water.

ssask3Groundwater tends to be used only by smaller communities and farmsteads. Although urban water withdrawals are large, household water consumption in the basin is relatively small. The reason for this is that almost all the domestic water used indoors returns to the aquatic system as wastewater; only water used outdoors tends to be consumed. If one includes stormwater runoff as part of the contribution of urban centres to streamflow, most urban centres in the basin return more surface water to the natural system than they withdraw. Urban centres also tend to be net contributors to the groundwater system, as water tables in urban areas can be as much as five metres higher than those in undeveloped areas. There are several reasons for this, the most important being excessive lawn watering.

The main advantage of urban water conservation, therefore, lies not so much in saving water, as in postponing the need for capital investments in water supply and wastewater treatment systems. Calgary, for example, has a goal of decreasing per capita water consumption by 30 percent in 30 years. Water-use efficiency goals of this magnitude are readily achievable; Denver uses about the same quantity of water today as it did in the 1960s, despite a 65 percent increase in population. Reduced water withdrawals also benefit the aquatic health of the streams receiving municipal effluents, by enabling more effective operation of wastewater treatment systems.

Safe drinking water and public health and environmental consequences of municipal effluents are shared concerns among municipal, provincial, and federal governments. The federal government has little direct authority over drinking water supplies, except in the case of federal lands such as First Nations reserves. Provincial governments have primary jurisdiction and responsibility for drinking water quality. However, a federal/provincial/ territorial government committee on drinking water standards develops and maintains Guidelines for Drinking Water Quality.12 The committee takes into account health assessments (both domestic and international), treatment costs, and other economic factors. The Guidelines specify maximum acceptable concentrations of substances known to or suspected of causing health effects.

Public concerns about safe drinking water can be addressed through source water protection, effective water treatment, a secure distribution system, and robust operating and control systems. Larger centres have the skilled personnel and financial resources to design, build, operate, and maintain a satisfactory water supply system. This is not always the case for smaller centres and First Nations reserves. Difficulties lie not only in the need to secure resources and skills to implement a water supply system, but also in particular problems related to protecting and enhancing local source waters, including meeting the need for innovative small-scale systems. In fact, rural water supplies in the basin rarely meet health and aesthetic objectives. The United States Environmental Protection Agency has observed that municipal water systems serving more than 20,000 people tend to be safer than smaller systems.

Read more… about the Canada Survey of Drinking Water Plants (2005 to 2007).

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Municipal wastewater consists of human and other organic waste, suspended solids, nutrients, microorganisms, and various household and industrial chemicals. It may also contain stormwater runoff in centres where combined sewers are still in use. All cities in the basin treat their wastewater before discharging it to the natural system. The treatment process reduces contaminant levels of the effluent, but the sheer volume of effluents discharged annually to the environment make urban wastewater an environmental concern.

Effluent suppresses oxygen levels in the stream and may contain suspended solids, nutrients, organic chemicals such as pesticides, and metals. Other contaminants may include pharmaceuticals, personal care products, endocrine-disrupting compounds, and brominated flame retardants. These effluents affect the quality of the receiving waters as well as the quality of the sediments in the stream, in turn affecting the plants and animals of the ecosystem. Effluents may also lead to human health and economic effects.

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Wastewater

Generally, municipal wastewaters are treated through a progression of processes usually identified as preliminary, primary, secondary, tertiary, and quaternary. These processes incrementally remove increasing amounts of suspended solids from the effluent stream and reduce the oxygen demands of the effluent. Sewage lagoons provide a level of treatment similar to secondary treatment. Some wastewater treatment systems in the basin also include nutrient reduction. Effluents are disinfected before release to the environment. All municipal effluents in the basin receive at least secondary treatment. Banff, Calgary and Saskatoon all perform advanced nutrient reduction.

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Stormwater

stormwaterPrior to the 1940s, cities constructed combined sewers to convey sanitary and stormwater runoff to receiving streams. Even as wastewater treatment facilities were in development, combined sewers continued to discharge untreated sewage to receiving waters during high-runoff events. These combined sewers still exist in the central cores of some cities in the basin. Cities are modifying infrastructure to reduce overflow incidents.

Recognizing problems associated with combined sewers, cities developed sewer systems exclusively for stormwater runoff. Early systems were aimed, primarily, at reducing property damages from flooding and allowing traffic to move during storms. Some of these systems caused physical damage to conveyance channels and to downstream properties, and little consideration was given to effects of stormwater runoff on aquatic resources or wildlife habitat.

Stormwater detention ponds were developed in the 1970s as a means of reducing physical damage from urban runoff, and as a means of enhancing environmental values. They have met with varying degrees of success. They will, in general, reduce downstream damages while maintaining reasonable quality water in the pond.

Stormwater runoff contains much lower levels of contaminants than sewage effluent, but flows of stormwater are much greater than those of sewage effluent and are often confined to pulses of flow during wet weather. These flow pulses contain contaminants from streets and parking lots. As wastewater treatment systems improve, effects of stormwater runoff on receiving waters become more apparent. Treatment of stormwater runoff will become an increasing requirement in the basin.