Environmental engineers design systems and solutions that prevent or remediate pollution of the air, soil and water. They have a long history of promoting public health through infrastructure and treatment systems that provide potable water, treat wastewater, and manage solid waste. Their work also includes water quality protection, flood prevention, stream restoration, land development and stormwater management and treatment. Environmental engineers design and use models to assess the environmental impact of current and/or proposed actions. Environmental engineers have been in the forefront of promoting sustainable designs and practices for all engineering disciplines to lighten the impacts of the built environment on natural systems. This has led to innovations in natural treatment systems, low impact development, and biologically based renewable energy. Environmental engineers do their work in ways that can assist society and policy makers in providing sound and sustainable environmental management.