Environmental Assessment
Volume B-3.9
Mine
Water Quality
Ambatovy Project
117
January 2006
Table 3.9-1 Madagascar Classification System for Surface Water Quality
Factors
Class A
Class B
Class C
Unclassifiable
(Class HC)
Classification
definition
Good quality:
multiple uses
possible
Moderate quality: non-
contact recreation
allowed; swimming
may not be allowed
Poor quality:
swimming not allowed
Excessive
contamination: no
use possible except
for boating
Biological Factors
dissolved oxygen (mg/L)
DO
≥
5
3 < DO < 5
2 < DO
≤
3
DO < 2
5-day biological oxygen
demand (BOD
5
)
BOD
5
≤
5
5 < BOD
5
≤
20
20 < BOD
5
≤
70
BOD
5
> 70
chemical oxygen
demand (COD)
COD
≤
20
20 < COD
≤
50
50 < COD
≤
100
COD > 100
presence of pathogenic
bacteria
no
no
no
yes
Physical and Chemical Factors
colour (TCU)
colour < 20
20
≤
colour
≤
30
colour < 30
n/a
water temperature (°C)
temperature < 25 25
≤
temperature < 30
30
≤
temperature < 35
temperature > 35
pH
6.0
≤
pH
≤
8.5
5.5 < pH < 6.0 or
8.5 < pH 9.5
pH
≤
5.5 or pH
≥
9.5
N/A
total suspended solids
(TSS) (mg/L)
TSS < 30
30
≤
TSS < 60
60
≤
TSS < 100
TSS > 100
conductivity (µS/cm)
conductivity
≤
250 250 < conductivity
≤
500 500 < conductivity
≤
3000 conductivity > 3000
TCU = True colour unit.
N/A = Not applicable.
Madagascar does not have water quality guidelines for the protection of aquatic
life. In the absence of national guidelines, international guidelines from other
jurisdictions including Canada (Canadian Council of Ministers of the
Environment [CCME] 2003) and the United States (US Environmental
Protection Agency [EPA] 2004) were used to screen baseline water quality.
Where CCME and EPA guidelines for aquatic life differed, the most stringent
guideline from both jurisdictions was compared to observed water quality data.
South African Aquatic Ecosystem Guidelines (Department of Forest and Water
Affairs 1996) were used to compare to assessment results because they are the
closest regionally approved set of water quality guidelines.
Screening results show that several metals including aluminium, arsenic,
chromium, copper, iron, lead, mercury, nickel and zinc occasionally had
concentrations exceeding either EPA or CCME aquatic life guideline values.
However, because the EPA or CCME guidelines do not take into account local
ecological conditions in Madagascar, exceedances of these guidelines should be
treated with caution. Indeed, it is not uncommon for baseline substance
concentrations to be higher than guideline values even in jurisdictions where they
