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I recently spent three weeks traveling down California's San Joaquin, which was named this year by the advocacy group American Rivers as the "most endangered" river in the United States. It's a river that all of us depend on -- 40% of U.S. fruits are grown in the Central Valley, where the river is located, as well as 80% of the world's almonds -- but that very few people care about.

I hope my trip will be some tiny part of changing that.

But for the San Joaquin to once again flow to the ocean -- and support a salmon population, as it once did -- it needs plenty of help.

Here are seven ways you can support this neglected waterway.

If you have other ideas, send me a note!

And look for other stories in this series at CNN.com/Change.

1. Restore half of the San Joaquin's flow

If I told you a river had half of its natural flow, that would seem like a problem, right? Like, where did the other half go? But restoring 50% to 60% of the San Joaquin's flow is a hopeful prospect -- something environmentalists are advocating for. That's because currently, in an average year, the San Joaquin only sees about a third of its natural flow, said Jon Rosenfield, from the Bay Institute. In a dry year, like this one, that number is more like 10%. The river goes dry for about 40 miles -- and doesn't reach the Pacific Ocean.

That's why I'd ask you to consider signing a Change.org petition asking the California State Water Resources Control Board to restore "60% of the San Joaquin River basin's natural flow in the winter and spring." Farmers might oppose such a proposal, since some of the water they use to grow crops would go down the river. But that water wouldn't be wasted -- it would be used to one again connect the San Joaquin to the ocean, and to revive a once-thriving salmon population. Salmon migrate from the ocean to the mountains via rivers, and the San Joaquin is so disconnected they can't thrive. They're a valuable economic resource, like crops, and they're part of a healthy natural system. The San Joaquin is a river that's been engineered nearly to death, but it doesn't have to be that way. The proposal to ask the water board to restore 50% to 60% of the San Joaquin's flow may sound wonky, said Rosenfield, but "it's probably the most important thing that is happening right now" in terms of the San Joaquin, he said.

2. Send low-income kids on a river trip

So many people live right along the San Joaquin and barely know it exists -- and this is particularly true in low-income neighborhoods like those in Modesto, California. "If you don't know about it, you don't care," said Ed Aguilar, a community organizer with Tuolumne River Trust. Ed's group has been trying to connect low-income people, including farmworkers and their families, with the rivers of California's Central Valley.

In response to this series, Tuolumne River Trust, which is named for a tributary of the San Joaquin, has set up a page where CNN readers can donate to send low-income community residents on 4-mile river trips on the San Joaquin. That's a potentially life-changing and river-changing experience. "The relationship between these riverside communities and the rivers is symbiotic," the group says on its website. "If the rivers are clean and healthy, the neighborhoods will benefit by having safe access to parks, swimming, boating and fishing. If the neighborhoods are healthier and safer, the rivers will benefit through greater care and stewardship."

I'd encourage you to donate to the group's efforts. A $50 donation enables one "riverside community resident" to go on a guided canoe trip down the San Joaquin.

Donate here. And I'll report back on how it goes.

3. Put a bucket under your shower

Californians are going to extremes to save water. They're putting buckets under their showers, to collect the water that otherwise would be wasted while the water's heating up. They're ripping out their lawns in favor of water-saving native vegetation. (Some communities are smartly paying them to do that, since lawns and other outdoor water uses account for more than a third of all urban water use in the Golden State, according to a state report.) And they're not flushing the toilet unless it's No.2. (!!) Many Californians care -- like, maybe an unsanitary amount -- about water conservation.

But, on the whole, it's not enough. Despite California Gov. Jerry Brown's calls for the state to reduce urban water use by 20% -- and despite the fact that electronic billboards are running save-water messages on California highways -- water use in the state actually increased 1% over last year, according to news reports.

People in California -- and everywhere -- should do more to save water. It's not a sexy topic, but it matters, and thinking about it helps connect us to the natural water cycle. Try National Geographic's "Water Footprint" calculator; water-saving apps, like Drip Detective and Tap the Tap, which turn conservation into a game; or Dropcountr, which compares your water use to average people who live in similar situations.

4. Support water-efficient farming -- and less of it

For the San Joaquin to survive, farms have to cut back on their water use in a serious and potentially painful way. That's something level-headed policy experts agree upon, but is heretical in the farming community. Farms account for 80% of the human use of water in the state. California has about 9 million acres of irrigated land -- and needs to eliminate 1 million of those acres in order to use water sustainably, said Jeffrey Mount, a senior fellow at the Public Policy Institute of California.

"It's almost inconceivable at this point," he said.

It's also a wise response to the coming era of climate change. Currently, the San Joaquin River is dry or stagnant for about 40 miles. Snowpack from the Sierra Nevada is expected to decrease drastically as the climate warms, reducing flow for many of the state's rivers. California is a place that has used engineering might -- moving water over mountains, through tunnels and down hundreds of miles of canals -- to try to control the water cycle. It has moved water from the northern part of the state, which is relatively wet, to the south, where Los Angeles and Central Valley farms are thirsty for water.

To adapt to the climate-change century, however, it needs to learn to live within its means. That calls for less farming, as well as radically improved efficiency.

California uses 6 million more acre-feet of water than "our rivers and aquifers can sustainably provide," according to a June report from the Pacific Institute and the Natural Resources Defense Council. Making agriculture and cities more water-efficient could save 14 million acre-feet of water per year -- more than twice the state's water deficit.

5. Petition to designate the upper San Joaquin a scenic river