For six years, a coordinated campaign has fought to save the Colorado River, influencing policy decisions like a recent interstate drought plan. But you can’t find it on Google. The Colorado River Sustainability Campaign has been an important behind-the-scenes player for environmentalists working on the waterway, which provides water to 40 million people. It is housed at the New Venture Fund, a tax-exempt charity based in Washington, D.C., that funnels money to dozens of advocacy campaigns on a variety of issues. There is no mention of the Colorado River Sustainability Campaign on the fund’s website, or anywhere in its tax filings. And those tax returns are opaque.