Fill in the Blanks (Reading & Writing)

Environmental agencies have warned that road salt used to melt winter ice is steadily —contaminatingcontaminatecontaminatedcontamination nearby rivers. Once dissolved, the salt —washeswashwashingwashed into drains and eventually reaches waterways, where it can harm fish and aquatic plants. Some councils are now —triallingtrialtrialledtrials sand or beet-based alternatives to reduce the —impactimpactingimpactedimpacts on freshwater ecosystems.