| http://www.w3.org/ns/prov#value | - The first North American Secchi Dip-In started in 1994 and now thanks to the support ofvolunteer programs and volunteers, the North American Lake Management Society, and theEnvironmental Protection Agency, the Dip-In database has grown to more than 41,000 records on morethan 7,000 separate water bodies (not including different sites, such as along rivers and estuaries).Macroinvertebrate, macrophyt
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