Every May the alewives push up Outlet Stream toward China Lake in a silver, thrashing crowd, and Vassalboro knows spring has actually arrived. A2Z Contracting & Property Maintenance is out about then too, running spring cleanups — winter sand raked off, matted leaves pulled from the beds, the lawn given room to breathe again. Then it is mowing, string trimming and edging clear through to leaf drop, on the yards around Webber Pond and at both village ends of town. Ground between the lakes and the Kennebec comes in dense and dark once the grass gets going. Keeping it that way is mostly a matter of showing up the same day every week and cutting it right.