1. Rivers of salt:
The Llobregat
How salt mining has destroyed some rivers in
the 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 group
Many thanks to Jordi Badia (Montsalat platform) and to the students of the
master course : “Indicadors d’estat ecològic de les aigües continentals” of the
year 2012

2. 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

3. 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 0
Conductivity: 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 plants
upstream of the mining area the biological quality at this point is good
and has been improved in the recent years.

4. The salt waste: Montsalat
The salt mine
waste mountain:
Montsalat

5. 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 size
compared with those in the background. No riparian vegetation.

6. 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 Landrera
Conductivity: 132 mS/cm;
Number of taxa (families): 2;
Biological quality: Very poor
The fauna inhabiting the stream is reduced mostly to Ephydridae, a salt tolerant
dipteran taxon. Observe the dead vegetation.

7. 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;

8. 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 Landrera
Conductivity: 1,3mS/cm;
Number of taxa (families): 18;
Biological quality: Moderate
Small Mediterranean stream, pools and riffles with some eutrophication.
Observe the Phragmites and other semiaquatic vegetation growing without problems.

9. Effects on tributaries
Between site 3 and 4: Salt incoming to the stream trough the
calcareous rocks
Conductivity of the resurgent water up to 55 mS/cm
Conductivity in the stream is close to 10 mS/cm.
Observe the dead vegetation in the resurgence area.

10. Effects on tributaries
Site 4: Riu d’Or 2 km downstream of the
resurgence area
Conductivity: 10mS/cm;
Number of taxa (families): 7;
Biological quality: Very poor
Again the Phragmites are very small in the river bed area

11. 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: Moderate
Most of the river water (up to 1 m3/s) is diverted into a channel to produce electricity, only
part of the river water (close to 100 l/s) circulates by the stream channel in this reach.

12. Salinity downstream of the mine area
Effects 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 0
The river is affected by the salt inputs and by other anthropogenic
stressors (sewage plants inputs), in addition the river is extremely
regulated by weirs.
Conductivity values are always higher than 1 mS/cm.
Biological quality is always poor, moderate in some spring of wet years.

13. Historical data
Historical 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

14. 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.