Corps plans more Montana dam releases to help sturgeon spawn
BILLINGS, Mont. (AP) — A plan designed to test whether boosting water releases from Fort Peck Dam in the spring could help endangered pallid sturgeon successfully spawn has been approved.
The U.S. Army Corps of Engineers released its environmental impact statement on Sept. 24 outlining its proposed path forward as well as the predicted economic impacts.
Under its chosen alternative, when reservoir water levels allow, the Corps would request that Fort Peck Dam begin increasing releases in April to see if mimicking spring runoff will attract pallid sturgeon into the Missouri River.
The concept is not a new one, U.S. Geological Survey research fish biologist Pat Braaten noted. In the early 2000s fisheries and biologists worked on test flows from Fort Peck to gather data but the push evaporated around 2007 when water levels dropped due to drier weather.
Mother Nature eventually provided proof of concept in the high water years of 2011 and 2018, Braaten said, as pallid sturgeon females moved up the river below the dam. Without managed flows like the Corps’ proposed tests, such opportunistic runoff scenarios provide the best chance for the fish to successfully spawn in the wild, he added.
Under the Corps proposal, the tests would fluctuate dam releases between April and July.
Beginning on April 16 — only when Fort Peck Reservoir’s elevation is at 2,227 feet and other downstream and runoff factors align — flows would be increased by 1,700 cubic feet per second each day until the peak flow at the Wolf Point gauge reached 16,000 cfs. That flow would be held for three days and then gradually decreased before being boosted in late May to 28,000 cfs. The peak flow would be held for three days, and then gradually decreased to 8,000 cfs and held there through mid-July.
“It’s built around a whole cascade of processes,” Braaten said, each of which has to work.
Despite the work of Corps scientists to develop models to design the best possible scenario, the agency hedged in its EIS by noting that whether the fish will “successfully spawn immediately below Fort Peck Dam remains a significant uncertainty” because of the unpredictability of weather, water temperatures and predation which “are highly variable, difficult to quantify, or otherwise uncertain.”
“You can think everything will work one year, and then the fish will throw you a curve,” Braaten said, making predictability an uncertainty.
The financial impacts to conducting such tests are estimated in the millions of dollars due to a loss of irrigation water for some Missouri River farmers later in the summer, a decline in power generation when water is dumped over spillways instead of through turbines, as well as a hit to the recreation economy on Fort Peck Reservoir as the lake is drawn down. The Corps is also concerned that flows could damage the Fort Peck spillway.
Gov. Greg Gianforte came out against the plan earlier this year, despite the fact that biologists with Montana Fish, Wildlife & Parks had long been advocating for the Corps to release warmer water over the spillway. Warmer flows increase pallid sturgeon larva growth rates, shorten drift distance and thereby decrease mortality by allowing the fish to mature before they hit Lake Sakakawea.
Pallid sturgeon were listed an endangered species in 1990. Only about 100 of the wild fish are believed to still live below the dam, although state and federal agencies have cooperated to stock hatchery raised pallids to ensure the species doesn’t disappear. An estimated 16,000 of the stocked fish are still alive in the Missouri and Yellowstone rivers, including some living above Fort Peck Reservoir.
Dams are the main impediment to the river fish successfully spawning. Their larva need eight to 14 days of drift time after hatching to mature, instead they are dying before then in the oxygen starved environments found at the head of reservoirs like Sakakawea and Fort Peck.
“We know they can spawn,” Braaten said.
On the Yellowstone River, a tributary to the Missouri, the Bureau of Reclamation is reconstructing Intake Dam — an irrigation impoundment — to include a two-mile-long bypass channel in hopes pallid sturgeon and other native fish will have access to another 165 miles of river above the dam to successfully spawn. The channel is expected to be operational by spring 2023.
“That’s a good thing, it increases the chances to get spawning and recruitment out of one of the rivers,” Braaten said.
Complicating whether runoff is manmade or natural are predictions of a drier climate, including less moisture falling as snow.
“We’ll really have to see where Mother Nature goes with that,” Braaten said.
DETAILS ON ECONOMIC IMPACTS
Details on the economic contributions of Fort Peck, Sakakawea and Oahe reservoirs can be found in the U.S. Army Corps of Engineer’s environmental impact statement.
In 2018, the three reservoirs were estimated to support more than 5.6 million recreation visits.
On an annual average, Fort Peck, Sakakawea and Oahe support $14 million, $140 million, and $32 million in recreation benefits, respectively.
In the highest visitation year the upper three reservoirs were shown to support approximately 535, 2,791, and 1,283 jobs at Fort Peck, Sakakawea and Oahe, respectively.
In an average year, recreation-based employment associated with Fort Peck Lake accounts for approximately 55% (378/687) of the tourism jobs (retail sales; arts, entertainment, and recreation; food and beverage; and accommodations) in the gateway communities.
Visitation and recreation benefits would decrease at Fort Peck Lake during flow release years, ranging from a decrease of 14,000 to 16,000 visitors and a decline in regional spending of $211,000 (-1.2%) to $450,000.