Rila Monastery Nature Park Management Plan - part - usaid

February 2004
2.3.5 River water quality
Surveys of the water quality along the valley of the Rilska River are limited in both
number and scope. Mountain waters, in general, have a low mineral content; they are
very soft and rich in oxygen. On the basis of a comparative analysis of samples taken
separately from the Iliyna and Rilska Rivers, at different altitudes above and below
their point of confluence, the following conclusions can be made:
• In its upper course, the Iliyna River shows lower oxidizability and
higher nitrogen content in the form of nitrates, making it possible to consider
the river water unpolluted with biological substances (Fig.5). A sample taken
at Brichebor shows a slight increase in oxidizability and decrease in nitrogen
content, evidence of a certain level of organic pollution – possibly from
stockbreeding farms along the river valley. Still, water pollution is relatively
low, as can be seen from a comparison with the admissible pollution norms.
Pursuant to Ordinance # 7/08.08.1986 of the Committee for the Protection of
the Environment, regarding the quality of surface waters (SG, # 96/1986), the
admissible pollution norms for Category 1 surface waters (as in RMNP) are as
follows: permanganate oxidizability: 10 mg/dm³; total hardness: 7 mg eq./dm³;
NO3: 5 mg/dm³; PO4: 0.2 mg/dm³.
мг/дм 3
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
900 1000 1100 1200 1300 1400 1500 1600
М н.в.
Перм. Окисл. Обща твърдост
NO3 PO4
Fig. 5: Values of some basic indicators of the quality of waters of the Iliyna River
by altitude zones
• Samples taken from the Iliyna River at places of different altitude along its course
show more or less the same results as with the Rilska (Fig.6). There is a certain
increase of the nitrogen content downstream of Rila Monastery;
Rila Monastery Nature Park
Management Plan -Draft
2004 - 2013
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