Customers of NSTAR who heat & cook with natural gas could be seeing a rate reduction just in time for winter. NSTAR is submitting a new supply rate to the State Department of Public Utilities that would lower the average price of a gas heating customer by $15 a month compared to last year. The supply rate, known as the cost of gas adjustment, reflects the price that NSTAR pays for natural gas which reflects a continued decline in natural gas prices due in part to abundant domestic supplies.