1817-1862 1948- 1955- aquaculture aridregionsecology arizona aspectdel'environnement biographies biography biologistes biologists brianj brothersandsisters cachelapoudreriver cachelapoudreriverregion canada coastalecology colorado communicationinwaterresourcesdevelopment concordregion congresses conifers conservation coursd'eau dams danuberiverdelta(romaniaandukraine) david descriptionandtravel desertecology earthsciences ecology ecosystemmanagement engineering environmental environmentalaspects environmentalconditions environmentalpolicy fisheries fisherymanagement forestecology freshwaterbiology freshwaterecology general geomorphology glencanyondamregion governmentpolicy grandcanyon guidebooks harvey henrydavid history homesandhauntsthoreau humanecology hydrology identification indigenouspeoples lakeecology lakefauna lakeplants lakes limnology marineecology massachusetts mississippiriver nat010000 naturalhistory nature new newmexico northwest owen pacific polarregions politicalaspects pêches rivers science socialaspects southwest streamanimals streamconservation streamplants streamself-purification taosregion technology travel travelowen unitedstates water-supply waterresourcesdevelopment watershedmanagement watershedrestoration watersheds watersupply west zebramussel écologiedescoursd'eau