MATERIAL DAMAGE FINDINGS
Material damage is any long-term or permanent change in the available quantity or quality of a water or soil source that will prevent its use or reduce its utility to an existing user within the CIA. In terms of the hydrologic balance, material damage would occur when post developmental operation (dam construction) levels exceed defined limits. These defined limits thus become the criteria or standards against which material damage will be evaluated. The increased public concern for the quality of the Nation's water supplies has led to the establishment of water-quality standards by various regulatory agencies. These standards generally are based on the maintenance and protection of specified water uses such as public and domestic water supply, agriculture, industry, aquatic life, and recreation. After the cumulative impact assessment has been made, the projected impacts for the parameters of concern (projected indicator parameters) are compared to the material damage criteria. Table 3 shows the comparison of material damage criteria for drinking water quality with that of existing standards.
TABLE-3
PARAMETER OBTAINED VALUES PERMISSIBLE LIMITS COMMENTS PH 6.53-7.74 6.5-8.5 Positive Impact DO 5-8 mg/l Should not be less than 3.0 mg/l Positive Impact Turbidity <10 - 75 NTU Should not be greater than 10 NTU Negative Impact Total Suspended Solids 21.3-110 mg/l 100 mg/l Negative Impact Color Colorless - Brown Colorless Negative Impact Alkalinity 20-68 mg/l 200 mg/l Positive Impact Sulphates 2.93-32.02 mg/l 150 mg/l Positive Impact Chlorides 4.9-24.9 mg/l 250 mg/l Positive Impact Sodium 4.433-32.02 mg/l 200 mg/l Positive Impact Potassium Nil-2.5029 mg/l - Positive Impact Nitrates Nil- 0.42 mg/l 45mg/l Positive Impact Phosphates Nil-0.032 mg/l 0.03 mg/l Negative Impact EC 0.005-0.44 ms/cm 50-1500 m
S/Cm Positive Impact Ammonia <0.2- 3 mg/l Should be less than 0.2 mg/l Negative Impact Coliform bacteria ND-Present Should be nil Negative Impact
The physico-chemical and biological parameter analyses indicate siltation [turbidity exceeds the limit (at Sharavathi 1 & 2, Sharmanavathi, Haridravathi and a small stream near Haridravathi), brownish color (almost at all sampling points), higher total suspended solids (at Haridravathi and near by streams)], higher phosphate [at a stream near Haridravathi], ammonia > 0.2 mg/l [mainly at Hurlihole, Yennahole, Haridravathi and a stream near Haridravathi] and coliform bacteria [at Sharavathi 2, Sharmanavathi, Haridravathi and its near by streams and at Muppanae forest area]. Based on these suitable mitigation measures and management strategies are formulated.