Enviros in New England worry that the region’s ski resorts are disrupting ecosystems by pumping large amounts of water from rivers and ponds to make snow for their slopes. The region now has plenty of natural snow, thanks to recent storms, but earlier this season New England had a glaring lack of the white stuff and many resorts are believed to have pumped more water than usual to make snowy trails. Enviros say snowmaking, which the ski industry has practiced for some 30 years, is imperiling river and pond habitats for fish and wildlife at a time of year when they are particularly vulnerable, and putting people at risk by reducing the capacity of rivers to dilute the municipal and industrial wastes that are dumped in them. Enviros complain that state agencies have little oversight of the resorts and are unaware of how much pumping has occurred and whether it has caused any problems.