Most water systems in the industrial regions of the world are already developed. At the same time they are highly complex. This is true with respect to physical configuration, managment, operation, political goals, environmental interactions, etc. Thus the basic systems are already in place. This realization is the starting point for any new water developments and for operation. From this we conclude that whatever we do to meet new exigencies requires an understanding of the presently in-place complex water systems. Their operation is the important thing. And how can we adjust their operation to meet the new demands upon the system? This book deals with complex water systems and their operation. Some chapters are highly theoretical while others are rooted in practical applications. How can we an~lyze the operation of a complex water system and determine how its performance can be improved? Several chapters on mathematical analysis give approaches involving different aspects of this problem. But operation also has political, management, and physical aspects. These problems are addressed in chapters by managers who operate such systems. The main theme of all chapters is how to deal with the different aspects of a complex water system, already in place. We feel the book, in dealing with this question could be a start for new theoretical premises in water planning.

Most water systems in the industrial regions of the world are already developed. At the same time they are highly complex. This is true with respect to physical configuration, managment, operation, political goals, environmental interactions, etc. Thus the basic systems are already in place. This realization is the starting point for any new water developments and for operation. From this we conclude that whatever we do to meet new exigencies requires an understanding of the presently in-place complex water systems. Their operation is the important thing. And how can we adjust their operation to meet the new demands upon the system? This book deals with complex water systems and their operation. Some chapters are highly theoretical while others are rooted in practical applications. How can we an~lyze the operation of a complex water system and determine how its performance can be improved? Several chapters on mathematical analysis give approaches involving different aspects of this problem. But operation also has political, management, and physical aspects. These problems are addressed in chapters by managers who operate such systems. The main theme of all chapters is how to deal with the different aspects of a complex water system, already in place. We feel the book, in dealing with this question could be a start for new theoretical premises in water planning.

During the past five decades, we have witnessed a tremendous evolution in water resource system management. Three characteristics of this evolution are of particular note: First, the application of the systems approach to complex water management problems has been established as one of the most important advances in the field of water resource management. Second, the past five decades have brought a remarkable transformation of attitude in the water resource management community towards environmental concerns and action to address these concerns. Third, applying the principles of sustainability to water resource decision-making requires major changes in the objectives on which decisions are based, and an understanding of the complicated inter-relationships between existing ecological, economic, and social factors. The Special Issue includes 15 contributions that offer insights into contemporary problems, approaches, and issues related to the management of complex water resources systems. It will be presumptuous to say that these 15 contributions characterize the success or failure of the systems approach to support water resources decision-making. However, these contributions offer interesting lessons from current experiences and highlight possible future work.

Legionnaires' disease, a pneumonia caused by the Legionella bacterium, is the leading cause of reported waterborne disease outbreaks in the United States. Legionella occur naturally in water from many different environmental sources, but grow rapidly in the warm, stagnant conditions that can be found in engineered water systems such as cooling towers, building plumbing, and hot tubs. Humans are primarily exposed to Legionella through inhalation of contaminated aerosols into the respiratory system. Legionnaires' disease can be fatal, with between 3 and 33 percent of Legionella infections leading to death, and studies show the incidence of Legionnaires' disease in the United States increased five-fold from 2000 to 2017. Management of Legionella in Water Systems reviews the state of science on Legionella contamination of water systems, specifically the ecology and diagnosis. This report explores the process of transmission via water systems, quantification, prevention and control, and policy and training issues that affect the incidence of Legionnaires' disease. It also analyzes existing knowledge gaps and recommends research priorities moving forward.