water Article Water Quality as an Indicator of Stream Restoration Effects—A Case Study of the Kwacza River Restoration Project Natalia Mrozi ´nska 1, Katarzyna Gli ´nska-Lewczuk 2 , Paweł Burandt 2 , Szymon Kobus 2, Wojciech Gotkiewicz 3, Monika Szyma ´nska 1, Martyna B ˛akowska 1 and Krystian Obolewski 1,* 1 Department of Hydrobiology, Kazimierz Wielki University in Bydgoszcz, 85-064 Bydgoszcz, Poland;
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[email protected] (M.B.) 2 Department of Water Resources, Climatology and Environmental Management, University of Warmia and Mazury in Olsztyn, Pl. Łódzki 2, 10-719 Olsztyn-Kortowo, Poland;
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[email protected] (S.K.) 3 Department of Agrotechnology, Agricultural Production Management and Agribusiness, University of Warmia and Mazury in Olsztyn, Pl. Łódzki 2, 10-719 Olsztyn-Kortowo, Poland;
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[email protected]; Tel.: +48-52341-9184 Received: 31 July 2018; Accepted: 12 September 2018; Published: 14 September 2018 Abstract: River restoration projects rely on environmental engineering solutions to improve the health of riparian ecosystems and restore their natural characteristics. The Kwacza River, the left tributary of the Słupia River in northern Poland, and the recipient of nutrients from an agriculturally used catchment area, was restored in 2007. The ecological status of the river’s biotope was improved with the use of various hydraulic structures, including palisades, groynes and stone islands, by protecting the banks with trunks, exposing a fragment of the river channel, and building a by-pass near a defunct culvert.