Lab analysis of complaint samples from the DPS Holding Pond, Belapur, reveals chloride levels nearly 8× above the safe limit and sulphate concentrations more than twice the acceptable threshold. While pH and BOD remain within range, the salinity surge signals significant contamination that demands urgent investigation and remediation.
"Our community deserves clean, safe water. The data from DPS Holding Pond is alarming — and the Rotary Club will not stay silent while our neighbourhood's environment is at risk."
— Rekha Sankhala, President · Rotary Club of Navi Mumbai Nerul (RCNN) · Joy of Giving| Parameter | Measured Value | Permissible Limit | Status | Ratio |
|---|---|---|---|---|
| pH | 7.5 | 5.5 – 9.0 | ✓ Pass | — |
| Suspended Solids (S.S.) | 1446 mg/L | Not specified | ⚑ Monitor | — |
| Dissolved Oxygen (D.O.) | 12.6 mg/L | 4.0 – 7.0 mg/L | ↑ Elevated | 1.8× |
| BOD | 99 mg/L | <100 mg/L | ✓ Borderline | 0.99× |
| Nitrate | 0.028 mg/L | <20 mg/L | ✓ Pass | 0.001× |
| Nitrite | 0.163 mg/L | — | ✓ Low | — |
| Phosphate | 0.328 mg/L | <5 mg/L | ✓ Pass | 0.07× |
| Chloride | 7778.44 mg/L | <1000 mg/L | ✕ CRITICAL | 7.8× |
| Sulphate | 2330.77 mg/L | <1000 mg/L | ✕ CRITICAL | 2.3× |
Chloride is the "salt" in saltwater. At 7,778 mg/L — nearly 8× the safe limit — the pond water is saltier than many brackish estuaries. This can corrode pipes and infrastructure, harm aquatic life, make water unfit for irrigation, and indicate illegal discharge of industrial brine or saline effluent into the holding pond.
Sulphate at 2,331 mg/L (2.3× the limit) can cause a bitter taste in water, trigger diarrhoea at high doses, and in stagnant ponds it fuels the growth of sulphate-reducing bacteria — producing foul-smelling hydrogen sulphide gas. It is often a marker of construction runoff, chemical dumps, or sewage infiltration.
Biochemical Oxygen Demand measures how much organic waste is decomposing in the water. The safe limit is 100 mg/L, and the pond sits at 99 — technically within range but at the very edge. Combined with 1,446 mg/L of suspended solids, the pond is turbid and ecologically stressed. Any further organic load could push it into failure.
pH at 7.5 is neutral and healthy. Nitrate (0.028 mg/L) and phosphate (0.328 mg/L) are both far below their limits, meaning there is no algal bloom threat from nutrient overload at present. Dissolved oxygen is actually slightly elevated — suggesting some aeration or algal activity — which is a silver lining in an otherwise concerning picture.
Suspended solids (S.S.) refer to particles floating in water — silt, clay, organic matter, algae, and pollutants that haven't dissolved. At 1,446 mg/L the pond water appears murky and turbid.
High S.S. blocks sunlight, smothering aquatic plants; provides surfaces for bacteria to colonise; and when solids settle, they smother the pond bed, destroying habitat for bottom-dwelling organisms. It also suggests significant surface runoff or construction activity upstream.
Safe DO for aquatic life is 4–7 mg/L. The reading of 12.6 mg/L is above the upper threshold — a condition called "supersaturation." This may sound positive, but it can indicate an algal bloom producing excess oxygen through photosynthesis.
Algal blooms are often triggered by nutrient enrichment, and at night — when algae respire instead of photosynthesise — DO crashes sharply, suffocating fish. The reading warrants careful monitoring alongside the other salt stress indicators.