Nature, food, and water 259or into a sewage-treatment facility. Older industries, built before basic pollution
standards, are doubtless less effective, on average, in maintaining clean streams
and rivers. Finally, old industries by towns are often in prime riverside locations
readily converted into wonderful parks and places for residents.
Four rivers
Among the streams and rivers of the GBRegion four are especially impor-
tant, the Ter, Tordera, Besos, and Llobregat (Color Figure43)(Acebillo and Folch
2000,Forman 2004a). Various tributaries of the four, as well as the Foix River,
also have regionally important water flows and other characteristics. Here the
contrasting rivers are briefly introduced:
(A) The Ter River system mainly north of Vic drains a large agricultural
landscape with abundant livestock, particularly pigs. The Ter then flows
eastward into three reservoirs in the Serralada Transversal which are
amajorwatersupply for the Barcelona area. Phosphorus, and particu-
larly nitrogen, from livestock wastes heavily pollute the river and cause
eutrophication problems in the reservoirs.
(B) In contrast, the Tordera River system is by far the most natural one in
the GBRegion. It originates in mountains and in the Girona area, flows
through some farmland, woodland, and town areas to a wide lower
floodplain delta covered with market-gardening, plus scattered buildings
and small wetlands.
(C) The Besos River system drains much of the Valles, formerly covered
with small farms and now being rapidly urbanized and fragmented. The
Lower Besos is channelized between transportation corridors and passes
through Barcelona to its mouth. Although floods occur, the Lower Besos
is commonly a small channel of water mainly emanating from sewage-
treatment plants. A specific plan for the Valles and Besos is needed.
(D) Finally, the Llobregat, as the largest river system, drains a highly hetero-
geneous forested, agricultural, and built area representing nearly half
of the GBRegion. The Lower Llobregat is a wide urbanization-lined flood-
plain, normally with rather little river water, that ends in an impres-
sive delta. The delta is covered with market-gardening and family-food
gardening, plus the Barcelona Airport, a town, and transportation cor-
ridors. The coastal strip includes limited amounts of coastal vegetation,
undeveloped coastline, development, and highly significant wetlands.
Overall, the Llobregat River is degraded by reduced normal water flow,
pollutants from nearby industries and development, overloaded sewage-
treatment plants, and structures encroaching on the floodplain.