The way I see it you also believe that to be true.
I guess all the runoff from rivers to the ocean is insignificant compared to irrigation water. Using your/their rising sea logic. At the rate of yearly river water runoff for centuries Phoenix should be beach front property.
All the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come, thither they return again. Eccl 1:7 (KJV).
Its not aur fault even if the sea level was rising, which it it ien’t; We have to be causing something or you will be out of Business, Al.