The role of the Kis-Balaton Water Protection System in the control of water quality of Lake Balaton

• Published in: Ecological engineering 2000-10, Vol.16 (1), p.73-78
• Main Authors: Tátrai, István, Mátyás, Kálmán, Korponai, János, Paulovits, Gábor, Pomogyi, Piroska
• Format: Article
• Language: English
• Subjects: Freshwater; Hungary; Lake Balaton; Nutrient removal; nutrient status; The Kis-Balaton water protection system
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/S0925-8574(00)00091-4

Since the 1960s the nutrient load of Lake Balaton has increased significantly, causing a clear decline in water quality. To retain the nutrients from the lake, the Kis (small)-Balaton Water Protection System (KBWPS) was designed on the lower part of the main inflow, the River Zala. The first part of the KBWPS started to function in July 1985. After a few years the system became hypertrophic. According to our results, approximately 80 000 t of suspended solids, 300 t of total phosphorus (TP), 250 t of phosphate-P, 850 t of total nitrogen (TN), and 2450 t of nitrate-N were retained between 1986 and 1997 by the first part of the system. At present, the KBWPS retains about half of the suspended solids, more than one-third of TP, more than two-thirds of phosphate-P, only one-tenth of TN, but more than half of nitrate. A 16 km 2 area of the second part has been operating experimentally since 1992. This part retains approximately 75% of suspended solids (mostly of phytoplankton origin) coming from the first phase, but the phosphorus retention is low due to release of phosphorus from sediments. Until 1991 there were no significant differences in monthly means of the chlorophyll-a content from the western part of Lake Balaton. Since that time the chlorophyll-a content has been decreasing in the lake. This decrease could have been the result of the combined effects of weather conditions (temperature, rainfall) and nutrient availability.