1. The 30-day average chloride concentration should be used to determine the appropriate 30-day average nitrite guideline.

Reference 3

1. For the buried embryo/alevin life stages these are in-stream concentrations from spawning to the point of yolk sac absorption or 30 days post-hatch for fish; the water column concentrations recommended to achieve interstitial dissolved oxygen values when the latter are unavailable. Interstitial oxygen measurements would supersede water column measurements in comparing to guidelines.

2. The instantaneous minimum level is to be maintained at all times.

3. The mean is based on at least five approximately evenly spaced samples. If a diurnal cycle exists in the water body, measurements should be taken when oxygen levels are lowest (usually early morning).

Reference 11

1. The continuous exposure average should be based on at least 5 samples, equally spaced in time and the averaging period should be not less than 4 days nor more than 30 days for freshwater and not less than 2 hours nor more than 30 days for marine or estuarine water. This is the threshold of chronic toxicity.

2. The duration in controlled intermittent exposures is the exposure period in minutes. This is the threshold of acute toxicity.

3. For the maximum controlled, intermittent exposure of aquatic life, the total duration of exposure in any consecutive 24-hour period should not exceed 2 hours. This is the threshold of acute toxicity.

4. TRC is the total residual chlorine in fresh water.

5. CPO is the chlorine-produced oxidants in marine or estuarine water.

6. The irrigation guideline applies to plants grown in soil-less media and should be applied as a maximum under continuous or intermittent exposure situations.

Reference 12

Water Use

Guidelines (in mg/L as total fluoride)

Raw Drinking Water

1.0 mg/L as a 30-day mean
—
1.5 mg/L as a maximum

Fresh Water Aquatic Life

0.2 mg/L maximum where water hardness is less than 50 mg/L as CaCO₃
—
0.3 mg/L maximum where water hardness is greater than or equal to 50 mg/L as CaCO₃

Marine Aquatic Life

1.5 mg/L maximum

Wildlife

1.0 mg/L as a 30-day mean
—
1.5 mg/L as a maximum

Dairy Cows, Breeding Stock
- long-lived animals

1.0 mg/L as a 30-day mean
—
1.5 mg/L as a maximum

Livestock
- high fluoride diets
- mineral or bone meal feed additives

1.0 mg/L as a 30-day mean
—
2.0 mg/L as a maximum

All Other Livestock
- normal diet

2.0 mg/L as a 30-day mean
—
4.0 mg/L as a maximum

Irrigation
- all soils

1.0 mg/L as a 30-day mean
—
2.0 mg/L as a maximum

Recreation

No guideline set

Industrial
- beer
- beverages
- processed foods

1.0 mg/L as a 30-day mean
—
1.5 mg/L as a maximum

1. Table values are in mg/L of total fluoride.

2. The freshwater aquatic life guidelines are interim until carefully controlled experiments can determine the appropriate levels of fluoride under various combinations of water temperature and hardness, measured as calcium carbonate.

Reference 13

1. g/kg salinity is equivalent to parts per thousand (ppt)

2. The guideline value is obtained by using the average pH, temperature and salinity field values, and is compared to the mean of the measured ammonia concentrations.

3. Intermediate values of pH, temperature or salinity should be interpolated linearly.

4. The freshwater guidelines apply at salinity less than 10 g/kg (see Tables 4 and 5)

Reference 14

1. g/kg salinity is equivalent to parts per thousand (ppt)

2. The guideline value is obtained by using the average pH, temperature and salinity field values, and is compared to the mean of the measured ammonia concentrations.

3. Intermediate values of pH, temperature or salinity should be interpolated linearly.

4. The freshwater criteria apply at salinity less than 10 g/kg (see Tables 4 and 5)

Reference 14