Trinity River summer flow cuts ill-advised

 

This piece was originally published in The Trinity Journal February 12, 2025.

By Tom Stokely

On Aug. 28, 2024, Trinity River Restoration Program hydrologist Dr. Todd Buxton presented his findings on pool stratification in the Trinity River. Though indicating more studies are in order, he proposed significantly reducing summer flows on the Trinity to allow pool stratification that mimics the pre-dam era.

Dr. Buxton maintained lower flows (down to 70 cfs from the current base flow of 450 cfs) would result in pool stratification and provide adequate temperatures for holding adult spring chinook salmon while reducing water velocities, allowing fish to reduce energy expenditures. He appeared to blame low spring chinook numbers on high summer flows.

However, his logic is seriously flawed. Cutting summer flows would significantly impact both spring chinook and the communities that depend on the Trinity River. Dr. Buxton also failed to note that some of the highest adult spring chinook runs on record followed nine to 12 years after the 450 cfs minimum summer flow standard was established. Contrary to his claim that the 450 cfs is a relic of the 2000 Trinity Record of Decision (ROD), it began nine years earlier in 1991.

A little history of Trinity River summer flows clearly is in order:

The 1955 Trinity River Act that authorized construction of Trinity and Lewiston dams required summer low flows of 150 cfs. That requirement is in federal law and is also contained in the Bureau of Reclamation’s 1959 State Water Permits, which require a total annual fishery flow of 120,500 acre-feet (af) per year. In 1981 Interior Secretary Cecil Andrus signed a decision authorizing a 12-year flow study that specified instream flow volumes of 140,000 af in critically dry years, 220,000 af in dry water years and 340,000 af in normal water years. The Andrus Decision allowed minimum summer flows of 300 cfs in all but critically dry years.

Unfortunately, such critically dry years soon developed, and flows were scheduled to go to 150 cfs in 1991. However, Interior Secretary Manuel Lujan signed another Secretarial decision in 1991 making 340,000 af the minimum Trinity River volume in all years. That was also included in federal law with Public Law 102-575 in 1992.

Also in 1991, the state approved temperature objectives for the Trinity River that, combined with the higher minimum annual flow volumes, required summer flow releases of 450 cfs. Some of the biggest returns of adult Trinity River spring chinook occurred in 2002 and 2003 with 450 cfs summer flows, casting serious doubt on Dr. Buxton’s assertion that the high summer flows are the problem for spring chinook salmon. Perhaps it’s something else: lack of higher winter flows, gravel dumps in the river that fill in pool volumes, disease problems in the Klamath River or running heavy equipment in the river during spring chinook spawning. These issues are ongoing, and their impacts have not been analyzed to any meaningful degree.

One of the main rationales supporting Trinity River summer flows that are higher than “natural” pre-dam flows is historic spring chinook behavior. Typically, they would migrate past Lewiston Dam to hold and spawn in cold tributaries upstream from the reservoirs. That habitat is no longer available. The Trinity River is clearly not a “natural” river and returning to “natural” summer flows would be a disaster.

The Trinity River Restoration Program recently achieved a major victory for their science program by obtaining approval of the Winter Variable Flows. If indeed more winter flows are needed to improve chinook and coho adult returns, it makes sense to wait and see results before taking such a dramatic step as cutting summer flows. It also would be a good idea to wait and see if removal of the Klamath dams reduces diseases that have, at times, killed up to 90% of the salmon smolts migrating to the Pacific Ocean.

The impact of cutting summer flows involves huge risks. If the pools don’t stratify as posited, it would likely kill adult Spring Chinook — especially during heat waves. There is no turning back the clock on dead fish.

Cutting summer flows would also have a significant impact on water quality. It would clearly violate Trinity River temperature objectives approved in 1992 by USEPA. Decreased river flows would likely cause severe impacts to the municipal diversions for Lewiston, Weaverville, Hoopa and Willow Creek, and to the hundreds of private diversions along the Trinity River. The lower Trinity River is already experiencing toxic blue-green algae blooms that impact fish, wildlife and municipal water supplies, including Hoopa’s diversions and many private diversions. Dramatically cutting summer flows can only result in increased algae contamination and perhaps even dry pumps, depriving people of water.

Other impacts would be the economic loss of one of Trinity County’s few remaining viable economic opportunities: summer whitewater boating. Following the 1991 increase in summer flows, commercial whitewater boating immediately increased by 1,500%. Combined with low Trinity Lake levels, fires and reduced steelhead fishing opportunities due to high winter flows, Trinity County has been identified as “the poorest county in California.”

The new administration in Washington, D.C., is not expected to be friendly to the Trinity River, and it’s likely that there will be attempts to divert additional Trinity water to the Sacramento River. Trinity River interests are horribly divided at a time when they should all be uniting. Moving ahead with plans to dramatically cut summer flows would further divide diverse Trinity River interests, exacerbating the extreme animosity that many Trinitarians feel toward the Trinity River Restoration Program.

Furthermore, cutting summer flows below 150 cfs would require an Act of Congress. It seems unwise and ill-advised to seek Trinity River legislation at a time when Washington is not friendly to salmon and dependent cultures and economies.

In conclusion, I urge the TRRP to drop its plans of cutting summer flows. It’s scary to many, dangerous, foolhardy and divides Trinity River interests at a time when we should all be coming together to protect the gains of the past 40 years. Please give current efforts an opportunity to show progress (or not) — and don’t muddy the waters with a new and perilous “grand experiment.”

Tom Stokely is a board member of the California Water Impact Network.

 
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