Water Quality
Preface
Establishing
the Guidelines
The Ministry
of Environment is developing ambient water quality guidelines
for British Columbia. This work has two goals:
- to provide
guidelines for the evaluation of data on water, sediment
and biota, and
- to provide
guidelines for site-specific ambient water quality objectives
The guidelines represent safe conditions or safe levels of a substance, and
are set to protect various water uses. A guideline is defined as "a
maximum and/or a minimum value for a physical, chemical or biological characteristic
of water, sediment or biota, which should not be exceeded to prevent specified
detrimental effects from occurring to a water use, including aquatic life,
under specified environmental conditions."
The guidelines
are applied province-wide, but they are use-specific, and are
being developed for the following:
- raw drinking
water, public water supply and food processing1
- recreation
and aesthetics2
- aquatic
life and wildlife, and
- agriculture
(livestock watering and irrigation)
The guidelines are established after considering the scientific literature,
guidelines and criteria from other jurisdictions and environmental conditions
in British Columbia. The scientific literature provides information about
the effects of toxicants on various life forms. This information may not
be conclusive since it is usually based on laboratory work that only approximates
field conditions. To compensate for this uncertainty, the guidelines have
built-in safety factors that are conservative, but reflect natural background
conditions in the province.
The guidelines
are subject to review and revision, as new information becomes
available or as other circumstances dictate. The working guidelines
in this document are established using the best readily available
published data.
________________________
1 The
guidelines apply to an ambient raw water source before it is
diverted or treated for domestic use. The Ministry of Health
regulates the quality of water for domestic use after it is
treated and delivered by a water purveyor.
2 Guidelines
relating to public health at bathing beaches will be the same
as those developed by the Ministry of Health, which regulates
the recreation and aesthetic water use.
