Discharging toxic waste in a river which is a source of drinking water for villagers will injure their health. But the villagers are unaware of it since the poisonous effluents are discharged secretively. When she knows that an act is harming innocent people, It becomes her moral duty to alert the villagers. If one becomes cognizant of all illegality, especially within an organisation one is working, it becomes her legal duty to inform the authorities. Otherwise, one will be colluding, though not directly, in an illegal act.
At a minimum, the villagers have to be tipped off so that they can at least take preventive steps to protect their health.
(b)
As she cannot afford to lose her job, she has to tread cautiously and indirectly. She can ask a reliable acquaintance to approach local authorities to test the river water quality. He/she should not bring her name into the matter. As a measure of abundant caution, he/she may in turn request another person or group to approach authorities for testing the river water quality. To stay in the background, she should not sign any applications or fill in any forms. She can also discreetly find out if the villagers are suffering from any water pollution-related diseases. The local PHC can be alerted through third parties about the source of pollution. PHC will get the water tested. Authorities will force the company to stop dumping toxic waste.