All West Marin beaches received top marks for water quality in a new report, but a few swimming holes on Lagunitas Creek were not so lucky. Heal The Bay, a Santa Monica environmental advocacy group, releases a beach report card, and three popular spots—at the Inkwells, White House Pool and the Green Bridge—received F and D grades this year, based on average levels of fecal bacteria. The sites didn’t fail for the same reason. At…