According to The Jordan Times and other sources, Jordan is accusing Syria of violating a water-sharing agreement over the Yarmouk river by cultivating summer crops on the banks of the River.
According to the article “Under agreements signed between the two countries, Syria’s share of water from the Wihdeh Dam, which is built on the Yarmouk River, is six million cubic metres (mcm) for agricultural purposes, provided that the dam reaches its full capacity of 110mcm.
But for the first time since its construction two years ago, the dam currently holds only 18mcm, and thus Syria’s share declines to 1mcm. The neighbouring country, however, is pumping more than its allocated share to water crops planted all the way from downstream of Wihdeh Dam to Al Raqqad Valley located on the banks of the Yarmouk River.”
Jordan contends that “The river’s flow dropped from 1,200 litres per second last year to 900 litres per second currently, which is blamed on the cultivation of crops on the river’s banks.”
You can find the following two treaties between Jordan and Syria related to the Yarmouk River on the IWLP website: