Chinook salmon are facing unprecedented challenges as their once-thriving populations struggle to survive. A new study published in the journal Ecosphere suggests that decades of human activities, including ocean harvest, artificial propagation and reservoir construction, have not only reduced the size of these fish, but also disrupted their ability to spawn successfully.

A decade ago, California fish advocates and water suppliers seldom crossed paths except as entrenched opponents in a court of law.

When salmon return from the ocean to the Klamath River after the world’s largest dam removal project ends this fall, they will regain access to 400 miles of historical spawning habitat their species has been cut off from for more than a century.