Why do federal courts have a jurisdiction on disputes involving the states? give an example of such a case

I think that the federal courts rule over state disputes because there needs to be an unbiased third party making unbiased decisions, unbiased rulings. An example would be if California and Colorado disputed over rights of water to the Colorado River, the federal court would intervene.

Sorry sir you did not give us the graph i typically but i'm very confused my conclusion is you're missing valuable information in the question