California officials are raising concerns that the intense heat waves across the state may cause nearly all young endangered salmon in the Sacramento River to die.

The California Department of Fish and Wildlife (CDFW) told CNN that there could be a “near-complete loss” of juvenile chinook salmon because temperatures have reached higher than 100 degrees for prolonged periods of time, which causes the river to overheat.

Those conditions, according to the department, create an environment where the fish are not able to grow beyond their egg stage.ADVERTISEMENT

“This persistent heat dome over the West Coast will likely result in earlier loss of ability to provide cool water and subsequently, it is possible that all in-river juveniles will not survive this season,” CDFW said in a statement to CNN.

The CDFW confirmed in a statement to The Hill that the possibility of a “near-complete loss” of young in-river Chinook salmon does exist, based on potential water and weather outlooks.

“Modeling of monthly operations predicts high levels of mortality for Chinook salmon during egg incubation in the Sacramento River due to limited cold-water pool in Lake Shasta and downstream water deliveries. Unanticipated depletions downstream have resulted in increased releases from numerous reservoirs in the Central Valley,” the CDFW said in a statement to The Hill. 

“The State Water Project and Central Valley Water Project are attempting to balance many beneficial uses, including municipal drinking water. Chinook salmon mortality during egg incubation could be higher than originally predicted. It’s an extreme set of cascading climate events pushing us into this crisis situation,” the department added.

California is one of a number of Western states that has experienced extremely high temperatures in recent weeks, according to the network.

A study out last week determined that the heat wave and drought are continued symptoms of climate change. The study suggested that such a heat wave would not be possible if human activity did not play a role in Earth’s temperatures increasing.

As temperatures continue to rise, a number of reservoirs in California’s Central Valley have rerouted water to cities and farmers, according to CNN. That move, however, has caused rivers to become more shallow and too hot for fish to develop from eggs, which can on average take at least 60 days to happen.