LANSING — A few things change for Lansing Board of Water & Light customers on April 16. That's the date they're eligible for help with overdue utility bills through a state emergency relief program. BWL, a city-run utility that provides electricity to roughly 97,000 residential and commercial customers in the Lansing area, does not participate in the Low-Income Energy Assistance Fund. That state program collects money from electricity customers through small monthly surcharges and distributes it to low-income people at risk of losing power or heat. BWL opts out of the program. That saves its electric customers a little less than $12 a year, but means its poor customers