Table 1: Summary of the physical and chemical parameters of the Lower Cross River study stations (January–August, 2011). Values are mean ± SE. The minimum and maximum values are noted in parentheses.

ParametersStation 1Station 2Station 3Statistical significanceMaximum permitted levels
SONWHO

Air temperature (°C)
(28.0–33.1)(29.6–34.3)(26.0–32.4)

Water temperature (°C) Ambient
(26.1–32.0)(26.0–32.3)(26.0–33.2)

Transparency (m)
(0.250–2.160)(0.400–2.195)(0.210–1.550)

Water level (m)
(3.86–10.015)A(2.40–9.62)A(5.30–13.99)B

TDS (mg/L) 500NHC
(20.0–40.0)(21.0–50.0)(18.0–40.0)

TSS (mg/L)0.0128 ± 0.005
(0.003–0.011)(0.001–0.04)(0.002–0.03)

TS (mg/L)
(20.0–40.01)(21.0–50.001)(18.0–40.0)

Flow velocity (m/s)
(0.047–0.230)(0.078–0.276)(0.031–0.262)

Electrical conductivity ( S/cm) 1000
(48.0–80.0)(41.0–80.0)(36.0–80.0)

pH 6.5–8.5NHC
(6.30–6.90)(6.50–7.04)(6.10–7.06)

Alkalinity (mg/L CaCO3)
(3.0–8.5)(3.0–10.0)(3.0–9.5)

Dissolved oxygen (mg/L)
(4.6–18.2)(4.0–19.8)(5.0–13.6)

BOD5 (mg/L)
(2.10–7.60)(1.70–8.20)(1.75–7.10)

COD (mg/L)
(102.45–211.2)A(67.11–158.14)B(48.30–127.52)B

Nitrate (mg/L) 5050
(2.06–8.17)(1.13–6.99)(1.01–4.85)

Sulphate (mg/L) 100NHC
(1.2–5.9)(0.4–4.7)(0.0–3.2)

Phosphate (mg/L)
(0.00–0.71)(0.00–0.45)(0.00–0.29)

Similar letters indicate means that are not significantly different from each other.
NHC means not of health concern at levels found in drinking water.
: not significant; : significant.