Rivers of salt: The Llobregat How salt mining has destroyed some rivers inthe Sallent area (Catalonia, NE Spain) and still is a threat for the Llobregat river ecosystem, the water supply of great Barcelona region and the health of more than 2 million people Narcís Prat Maria Rieradevall, Pau Fortuño and the members of the F.E.M. research groupMany thanks to Jordi Badia (Montsalat platform) and to the students of themaster course : “Indicadors d’estat ecològic de les aigües continentals” of theyear 2012
Salt effects in the vicinity of the mines: Sites studied Vilafruns salt waste disposal L68 Balsareny Usptream of salt area (restored in 2011) (mesocosm’s site) Torrent Conangles 1 Sallent village Torrent Soldevila Llobregat (Botjosa) 2 5 Mine Water with salt percolates facilities) Riu d’Or though the calcareous rocks 3 Main salt waste disposal 4
Rivers of salt: The Llobregat The Llobregat before the salt: Balsareny station In red: conductivity; in blue: biological quality (EQR values) L68 - Llobregat a Balsareny EQR IBMWP Conductivitat (µS/cm2) 1.00 2500 0.80 2000 0.60 1500 0.40 1000 0.20 500 0.31 0.41 0.22 0.15 0.23 0.15 0.24 0.30 0.79 0.85 0.46 0.40 0.55 0.75 0.24 0.44 0.72 0.49 0.78 0.53 1.13 0.00 0Conductivity: 0,6 mS/cm; Number of taxa (families): 30;Biological quality (IBMWP index based on macroinvertebrates): good.Despite the river regulation and the many villages and sewage plantsupstream of the mining area the biological quality at this point is goodand has been improved in the recent years.
The salt waste: Montsalat The salt mine waste mountain: Montsalat
Effects on the Llobregat river and tributaries Site 1. Riera de Conangles. Water coming from a salt mine waste recently restored (Vilafruns). Subterranean inflow in the stream has conductivities up to 50 mS/cm.Conductivity: 4,5 mS/cm;Number of taxa (families): 16;Biological quality: poor.Observe that the Phragmites living into the river are very small in sizecompared with those in the background. No riparian vegetation.
Effects on the Llobregat river and tributaries Site 2: Torrent Soldevila, Salty water coming from the actual main salt waste deposit (active, increasing every year). Picture: Rubén LandreraConductivity: 132 mS/cm;Number of taxa (families): 2;Biological quality: Very poorThe fauna inhabiting the stream is reduced mostly to Ephydridae, a salt tolerantdipteran taxon. Observe the dead vegetation.
Effects on the tributaries Site 2: Inlet to the Soldevila Torrent, water coming from the salt waste. Left: in normal conditions; Right: after a heavy rain.Conductivity: Left 177 mS/cm; Right 4,5 mS/cm;
Effects on tributaries: Unaffected headstream Site 3: Riu d’Or, just before the entrance of salt coming from the Salt Waste. An agricultural area with many fields.Picture: Rubén LandreraConductivity: 1,3mS/cm;Number of taxa (families): 18;Biological quality: ModerateSmall Mediterranean stream, pools and riffles with some eutrophication.Observe the Phragmites and other semiaquatic vegetation growing without problems.
Effects on tributaries Between site 3 and 4: Salt incoming to the stream trough the calcareous rocksConductivity of the resurgent water up to 55 mS/cmConductivity in the stream is close to 10 mS/cm.Observe the dead vegetation in the resurgence area.
Effects on tributariesSite 4: Riu d’Or 2 km downstream of theresurgence areaConductivity: 10mS/cm;Number of taxa (families): 7;Biological quality: Very poorAgain the Phragmites are very small in the river bed area
Effects on the LLobregat river: Entrance of salt Site 5: Llobregat river at La Butjosa. In this area there is a large inflow of subterranean salt water in the middle of the river. In the bottom of the river conductivities of sediments are close to 20 mS/cm.Conductivity: 2,5 mS/cm;Number of taxa (families): 18;Water quality: ModerateMost of the river water (up to 1 m3/s) is diverted into a channel to produce electricity, onlypart of the river water (close to 100 l/s) circulates by the stream channel in this reach.
Salinity downstream of the mine areaEffects downstream (15 Km away form the mine area):Conductivity and biological quality downstream of the salt mines L102 - Llobregat al Pont de Vilomara EQR IBMWP Conductivitat (µS/cm2) 1.00 2500 0.80 2000 0.60 1500 0.40 1000 0.20 500 0.26 0.15 0.08 0.18 0.14 0.04 0.08 0.13 0.33 0.48 0.42 0.25 0.24 0.37 0.26 0.18 0.34 0.23 0.15 0.24 0.00 0The river is affected by the salt inputs and by other anthropogenicstressors (sewage plants inputs), in addition the river is extremelyregulated by weirs.Conductivity values are always higher than 1 mS/cm.Biological quality is always poor, moderate in some spring of wet years.
Historical dataHistorical data since 1979, sampled twice every year since 1994(macroinvertebrates) http://www.ub.edu/fem/ http://ecobill.diba.cat/ Guardiola Salt mines are the breaking point for the Salt Mines biological quality of L68 water (Index L102 IBMWP). Changes from green (good) to yellow (moderate) or Area of the next slide orange (poor) colors St Boi Potabilization plant Molins de Rei
Effects on water supply of the great Barcelona region Molins de Rei (Red color, very poor, in the previous slide) 1.00 4000 Water supply intake 0.80 3000 0.60 2000 0.40 0.20 1000 0.00 0 Llobregat river Water supply plant This plant supplies water for up to 2 million people and due to its salt content many secondary products are produced during the potabilization process (as trihalometanes and bromides). Recently a RO process has been added to the potabilization process to guarantee the accomplishment of the levels of such secondary products in the water supplied.