**Since the government is responsible for making a lot of this information publicly accessible, your best bet is start with a web search engine like Google.**
Before you delve into those government sources, you need to know:
I'm interested in doing a legislative history on water conservation policies in Colorado. So here is my search in Google on: water conservation laws colorado
The first few results take me to the Colorado Water Conservation Board website which lists current bills going to the Colorado legislature and a list of related state statutes, rules, and policies! Another result is the Citizen's Guide to Colorado Water Law which provides a comprehensive history of water regulation in Colorado.
Either way, I realize now there are a lot of laws and policies involved with this topic, so I need to further narrow. I decide to focus on ground water and I see that the Colorado Ground Water Commission is the main regulatory agency involved, so I jump over to their site to learn more.
On that site, I read about the Ground Water Management Act and the Colorado Ground Water Commission policies. Now I'm ready to jump into the Colorado Revised Statutes to start my legislative history of the Colorado Ground Water Management Act.