HOPKINTON - There’s going to be an emergency response test this Thursday May 4 at the Eversource liquefied natural gas plant in Hopkinton. Expect a lot of emergency vehicles around for the required test which is scheduled to go from about 8am to 1pm.  And the Hopkinton Water Department says the drill could lead to your water being discolored for a couple of days because they will be using fire hydrants at high velocity and high volume. Water Department Manager Eric Carty says that discoloration could go on for a few days.