In California, where epic Sierra Nevada snowpack and “the Big Melt” have substantially increased the stakes for reservoir managers, officials say they’re taking steps to protect the state’s water systems from hackers, terrorist attacks and natural disasters, such as the flooding that temporarily severed the Los Angeles Aqueduct — the city’s water lifeline to the Owens Valley. But experts say the challenges are numerous. Many of the systems in California and nationwide are still operating with outdated software, poor passwords, aging infrastructure and other weaknesses that could leave them at risk. … Andrew Reddie, an assistant professor of practice in cybersecurity at UC Berkeley’s School of Information, said much of the problem is “driven by the fact that the infrastructure is really, really old, and ultimately predates the era that we find ourselves in now, where we actually bake cybersecurity into these … systems by design.”