San Diego County residents are turning to rain barrels to make the most of Tuesday’s rainfall, with environmental advocates saying even small amounts of precipitation can provide months of garden irrigation. A 50-gallon rain barrel can capture significant amounts of water during San Diego’s infrequent rain events, according to Jessica Toth, executive director of the Solana Center for Environmental Innovation. … Through the rain barrel program, they’ve kept about 90,000 gallons of water from going into the rainwater system.