US agencies have sued the fate of the rare Rio Grande minnow

ALBUQUERQUE, NM (AP) — Environmentalists Wednesday accused the U.S. government of not doing enough to ensure the survival of the Rio Grande’s silverfish as drought tightens its grip on one of the longest rivers in the West.

In a lawsuit filed in federal court, the WildEarth Guardians group asked a judge to force the Bureau of Reclamation and the Fish and Wildlife Service to reevaluate the effects of water management activities on endangered fish.

They also want federal officials to develop enforcement measures to prevent dams and diversions along the stretch of the river through New Mexico’s most populated region from jeopardizing the minnows.

The tiny fish was declared endangered almost 30 years ago and has been the subject of much controversy over the decades. The challenges have only increased in recent years as demands on the Rio Grande have increased due to climate change, with snowpack melting earlier and strong winds further drying out the thirsty soil and limiting the amount of spring runoff reaching the river.

Like the Colorado River and other western streams, record flows are becoming normal for the Rio Grande.

Parts of the Rio Grande at the south end of Albuquerque dried up completely earlier this year, something they hadn’t done in more than 30 years. Teams of biologists scrambled to collect small fish from puddles in the river bed before they dried up.

“Unsurprisingly, silverfish populations remain in crisis,” said Daniel Timmons of WildEarth Guardians. the native species that call the river home.

Timmons said the status quo is a recipe for minnow extinction.

The Fish and Wildlife Service and the Bureau of Reclamation declined Wednesday to comment on the ongoing litigation.

Management of the Rio Grande is based on decades-old water sharing agreements that also involve Colorado, Texas and Mexico. The irrigation districts that supply water to thousands of farmers up and down the river valley are also part of an equation that includes the basic water rights of Native American communities located along the river and the Hispanic enclaves that irrigate their crops through traditional canals. called acequias.

In some cases, changing the dynamics of Rio Grande management would require congressional action.

The Bureau of Reclamation has for years worked closely with irrigation districts, tribes, the City of Albuquerque and other water rights holders to release water for fish when the river was in danger of drying out or to mimic spring flows and encourage spawning.

There was no extra water this year.

A bureau-funded study released in October indicates that the minnow’s status appears heavily dependent on ensuring sufficient seasonal fluxes and habitat conditions that promote successful spawning.

The WildEarth Guardians in their complaint blame “a century of unsustainable water use and mismanagement of the Great” for conditions that barely allow minnows and other protected species to survive. The group argues that the Rio Grande has been transformed into a conduit rather than a “living river” with variable but persistent flows.

Conservationists dispute the findings of a 2016 biological opinion adopted by the agencies that said water operations in the Medio Rio Grande could not have endangered endangered species or adversely affect their habitat.

Measuring approximately 3 inches (7.62 centimeters) long, the silverfish was historically one of the most abundant and widespread aquatic species in the Rio Grande, found from Espanola downstream nearly 1,000 miles (1,609 kilometers) to the Gulf of Mexico. Biologists say it has disappeared from more than 95% of its historic range.

There have only been three times in the past 26 years — in 1995, 2005 and 2017 — that the population density in the Middle Rio Grande has exceeded the density at the time the minnow was listed in 1994.

The Fish and Wildlife Service had set a goal of having at least 5 fish per 100 square feet. This has only been achieved twice in consecutive years. In October 2022 the density was 0.17 fish per 100 square meters.

The lawsuit claims that regarding climate change, scientists predict Rio Grande flows will decline by at least a third and likely by half by the end of the century due to rising temperatures, significantly impacting silverfish and on its habitat.

The complaint also notes the effects of river management on the southwestern willow flycatcher and yellow-billed cuckoo.

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