One-third of Jerusalem's sewage runs untreated into the West Bank, ruining the historic Kidron Valley. Now an Israeli-Palestinian team is working to rehabilitate it.
Although an economic boon, tourism can be a destructive force for the environment. Israel, filled with religious tourism destinations, is exploring ways to make pilgrimages sustainable.
Six Olympic-size pools of trash and sewage are dumped in Kidron Valley, which abuts Jerusalem's holiest sites, every year.