A reservoir in Hingham was shut down yesterday after a man was seen throwing something into the water, police said. At 8:09 a.m., Hingham police received a report from a resident who saw the man throw something into Accord Pond, Hingham police said. After investigating, staff from the Aquarian Water Co. elected to shut down the reservoir as a precaution, police said. The State Police dive team checked the water, but did not find anything. Accord Pond serves Hingham, Hull, and a portion of Cohasset. The company has other water sources, so water service was not affected.