More than 5 million people live near Lake Urmia in northwestern Iran, one of the world's largest hypersaline lakes. Over the past two decades, the lake has lost 95% of its volume, lake level has dropped more than 7 m, and lake restoration has gained widespread interest. The government seeks a uniform "ecological" target lake level of 1274.1 m above sea level to lower salinity below 240 gL-1 and recover brine shrimp (Artemia spp.) and flamingos (Phoenicopterus roseus).

We have synthesized over 40 years of available data, defined 8 ecosystem services for human health, water quality, ecology, recreation, and economy (Box 1), and related each service to lake levels with uncertainties (Box 2).