I'm building a 28' Sailboat and just got transferred to Michigan. The boat will now be used on Lake Michigan. The Michigan Department of Environmental Quality tells me that there is no discharge of any type allowed. Does everyone plumb all the greywater to holding tanks for pumpout? Seems like a large tank and frequent pumpouts would be a problem. Are diverter valves allowed for sinks to drain to seacocks in the event that the boat is taken to waters where the discharge of greywater is permitted? I'm not familiar with the regulations and state officials haven't been very helpful.