In this week’s Environment Report, let’s focus on an issue that doesn’t always get much attention in Southern California: the rivers of Northern California. Every so often, people get together and divide a river. That’s been happening a lot lately in the final throes of Gov. Jerry Brown’s term. State and federal water officials have worked furiously to redo how we all share the Sacramento and the San Joaquin rivers and their numerous tributaries. At stake for cities and farms is how much water will be available and at what price. At stake for fish is their very existence.