EcoWatch: Three million gallons of brine, a salty, toxic byproduct of oil and natural gas productionalso known as fracking wastewaterspilled from a leaking pipe in western North Dakota. State officials say its the worst spill of its kind since the fracking boom began in the state. The spill was reported 17 days ago when Operator Summit Midstream Partners found a toxic leak of salty drilling waste from a pipeline in the heart of the Bakken oil boom. Officials say theres no immediate threat to human health...