What would be some grassroots options each of us on HT could take part in? It is definitely a daunting task on a broad level, but I feel our collective energy/efforts/money could be targeted towards the initiatives we all give a damn about.
The groups you mention are a great state. American River's does a ton on Clean Water, as does Trout Unlimited.
Grassroots is being involved in your local scene. Contact your County Commissioners, State Legislators, and others to make sure they know your position. When contacted elected officials, don't ask, "Why did you vote for that?" They will have some part-line BS and I don't really care why they voted for it, rather I want them to know it is against what their constituents want. Be professional and tell them how you feel on the issue, taking away the opportunity for them to rationalize and use generic terms of "local control, etc. They are to represent the people, whether you voted for them or not, making it more important for them to hear loud and clear what your position is.
It starts with you being informed. From there, informing your circle of friends and family. From there, your community and elected officials. Information is the key. Does anyone really think we need "dirtier water?"
When I hear people complain about the Clean Water Act, I ask for an example that has them so pissed off. To date, not a single example has been provided. I think part of grassroots activism is pushing back on the barstool rumors and forcing people, often family and friends, to think about it. They usually are faced with the "look in the mirror" of whether or not they are just regurgitating party line rhetoric they heard on talk radio or do they have a true concern based on facts/examples.
I know for many, this Clean Water issue causes some squirming. People they voted for due to positions on other issues are the ones behind it. Now, to get change on other issues comes this big problem. So, are people who voted for these folks going to be apologists or are they going to contact that elected person and say, "Hey, I voted for you, but this is bullchit. What is it about clean water that bothers you?"
I am hoping when Americans vote for someone they don't feel the obligation to be apologists for every idea that elected person might support. Hell, every person I have ever voted for did something I disagreed with. I felt it was more important for me, someone who voted for that person, to let them know the foolishness of their vote than to just let their political opponents criticize them. I do worry that America feels too much committed to the party system and the mostly terrible candidates that system produces, making them less likely to criticize someone they voted for.
Probably not a good answer, but the manner by which I do grassroot activism. And it seems pretty effective when done in large numbers.