Yes water cooling of the inlet air is common on stationary GTs. The compressors are density sensitive and produce less powe as the density drops. S&L GE aircraft derivatives are rated at around 60MW, but derated to around 50MW in the Goldfields. Super pure water is often injected just before the combusters. Is converts to steam (a steam turbines effect) and cools the combusted exhaust gas and allows more fuel to burn and a consequential power output. Some aircraft also do this to compensate for air density power loss in hot environments on take off. Super pure water is expensive to make so water injection is only used when an increased power is needed, or in power generation to the grid makes it economic. Walnut shells are often used in the air to clean blades.