Citation: ˇ Cegar, S.; Denona Bogovi´ c, N.; Jugovi´ c, A. Impact of Intersectoral Dependencies in National Production on Wastewater Discharges: An Extended Input–Output Study of the Croatian Economy. Water 2022, 14, 2122. https://doi.org/10.3390/ w14132122 Academic Editor: Juan Carlos Leyva Díaz Received: 2 June 2022 Accepted: 1 July 2022 Published: 3 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). water Article Impact of Intersectoral Dependencies in National Production on Wastewater Discharges: An Extended Input–Output Study of the Croatian Economy Saša ˇ Cegar 1, *, Nada Denona Bogovi´ c 1 and Alen Jugovi´ c 2, * 1 Faculty of Economics and Business, University of Rijeka, Ivana Filipovi´ ca 4, 51 000 Rijeka, Croatia; nada.denona.bogovic@efri.hr 2 Faculty of Maritime Studies, University of Rijeka, Studentska ulica 2, 51 000 Rijeka, Croatia * Correspondence: sasa.cegar@efri.hr (S. ˇ C.); ajugovic@pfri.hr (A.J.) Abstract: The Croatian economy performs unfavorably in terms of the impact of production on wastewater discharges, which is particularly pronounced in the industrial sectors. Each unit of gross industrial value added produced in Croatia generates significantly more wastewater discharges than in most European countries with a similar level of economic development. Moreover, in 2020, only 26.9% of the total industrial wastewater discharges of the Croatian economy were treated, while 76.2% of the total industrial wastewater discharges were directly discharged into the environment. Since most of the industrial production in the Croatian economy is destined to meet the intermediate needs of other sectors, policy makers in Croatia must take into account that the level of industrial wastewater discharges is also influenced by the production level of sectors that depend on the intermediate products of wastewater-intensive industries. For this reason, we developed a wastewater extended input–output model of the Croatian economy to determine and analyze the impact of intersectoral linkages in Croatian production systems on the amount of untreated wastewater discharges. The results of the study show that wastewater flows in the Croatian economy are largely generated by the processes of production and consumption of intermediate products from the chemical and petroleum refining sectors, which also account for the largest share of the calculated wastewater footprint of total Croatian production. In light of the emerging empirical evidence, it can be concluded that targeting market-based and regulation-based measures at wastewater-intensive producers is not sufficient to reduce the relatively high level of untreated wastewater discharges in the Croatian economy. There is also a need for appropriate integrated policy measures in sectors that have a large wastewater footprint due to their established supply chains. Keywords: Croatian economy; EEIO analysis; indirect wastewater intensity; cumulative wastewater intensity; wastewater footprint; forward and backward linkages 1. Introduction Wastewater streams discharged into water reservoirs are of great concern as they contribute the most to inorganic, organic and thermal pollution of water resources [1]. By definition, wastewater is water used in households, industries or other economic and social facilities that does not serve a useful purpose or does not meet physical, chemical, biological or other water quality standards without adequate treatment [2] (p. 7). Since raw wastewater streams contain pollutants, bacteria and viruses that can seriously damage ecosystems and endanger human health, adequate wastewater treatment prior to discharge into the environment is an important requirement for maintaining and improving the quality of available water resources [3]. Domestic wastewater, service wastewater and man- ufacturing wastewater are critical types of wastewater, of which manufacturing wastewater is more difficult to treat due to its complex pollution components and high concentration of pollution [4]. In order to reduce overall wastewater discharges, it is particularly important Water 2022, 14, 2122. https://doi.org/10.3390/w14132122 https://www.mdpi.com/journal/water