By

Nate Seltenrich
About the author

Nate Seltenrich is a freelance science and environmental journalist who covers infrastructure, restoration, and related topics for Estuary. He also contributes to the San Francisco Chronicle, Sonoma and Marin magazines, the journal Environmental Health Perspectives, and other local and national publications, on subjects ranging from public lands and renewable energy to the human health impacts of climate change. He lives in Petaluma with his wife, two boys, and four ducks. www.nate-reports.com

Articles by Nate Seltenrich

Groundwater pumped from subsided islands back into Delta channels through 200 or more active outfalls can be laden with excess nitrogen transported from island soils, report the authors of a new study.

The Sacramento-San Joaquin Delta contains more than 50 peat islands. Most have subsided—some as much as three meters — as a result of drainage for farming, and must maintain artificial water tables below the land surface via managed pumping. According to researchers from the University of California at Santa Cruz and the US Geological Survey, these pump stations are an underappreciated source of nutrients in nearby waters, with potentially significant implications for habitat and water quality.   To get a...
Read More
diagram of fish net trawl

Fish monitoring surveys in the San Francisco Estuary net different numbers of different fish species depending upon when and how they sample.

According to a new study published in San Francisco Estuary and Watershed Science, even surveys that target the same part of the water column can come up with significantly different catches. The study’s authors analyzed decades worth of data from the California Department of Fish and Wildlife (CDFW) Fall Midwater Trawl, which spans from San Pablo Bay to the upper Delta; CDFW’s San Francisco Bay Study midwater and otter trawls, covering the South Bay to the central Delta; and the...
Read More

Natives Who Can Rough It

Name a native fish. One that spends lots of time in the Delta. One that’s not a salmon, smelt, or sturgeon. One whose population isn’t plummeting, and in fact seems to be doing just fine. By now the list of possibilities has been shortened severely — though not exhausted. A number of native fish still ply Delta waters in stable numbers, but precisely because there are no restoration projects, monitoring programs, or conservation efforts designed to save them — or...
Read More

A large pulse of water sent through the Yolo Bypass in summer 2016 boosted phytoplankton biomass and food web conditions in Cache Slough and the lower Sacramento River, a new report confirms.

 “Our goal was to improve estuarine habitat by increasing net flows through the Cache Slough Complex to enhance downstream transport of lower trophic-level resources, an important driver for fish such as the endangered Delta Smelt,” write the authors—including esteemed (and recently retired) California Department of Water Resources lead scientist Ted Sommer—in the latest issue of San Francisco Estuary and Watershed Science. The pulse occurred over three weeks in July, a time when flows in the region above Cache Slough are...
Read More

Invasive Species Breakdown

The invasion of the Delta continues, with new plants and animals threatening to upend ecosystems alongside established non-native species like largemouth bass and spartina. Preventative measures, early detection, and rapid response to novel threats are all key in protecting the Delta from further disruption. But the concepts of community involvement and reconciliation ecology also encourage land managers to consider non-natives with nuance. This means accounting for the cultural and ecological values of invasive species and, in some cases, learning to...
Read More

Saving Water Under the East Bay

It’s a matter of semantics as to whether the Bay Area ever really left the drought of 2014-2017 before staring down another, more severe one beginning last year. But a huge lesson for our entire state from that “first” water shortage still being learned today is that more attention must be paid to groundwater. That’s true even in the urban East Bay, where the East Bay Municipal Utilities District (EBMUD) and the City of Hayward are developing a plan to...
Read More
Smelt cam photo

Monitoring Delta smelt with an underwater camera could be safer and more effective than with a traditional trawl.

Standard smelt surveys rely on the use of boat-driven nets, which trap fish by funneling them from the wide mouth of the net to the closed end (known as the cod end). To check their catch, researchers must pull the net and its contents from the water. But this additional handling can harm and even kill the same fish that wildlife agencies are trying to save with the support of robust, long-running monitoring efforts. There may be a better way:...
Read More

Three Ways to Feed the Marsh

Seal Beach is drowning. As a result of sea-level rise, subsidence, and limited sediment supply, much of the 920-acre National Wildlife Refuge in Orange County can no longer keep its head above water. Pacific cordgrass, normally exposed at low tides, is being completely inundated. Rare nesting habitat for the endangered light-footed clapper rail is disappearing at high tides. It’s a marsh manager’s worst nightmare, and a potential harbinger of things to come later this century for tidal wetlands up and...
Read More

Electrofishing is a powerful but underutilized tool for monitoring Delta fish, particularly species favoring “structured” habitats that are difficult to sample using more common methods like trawls and seines.

By analyzing fish catch data from past surveys, researchers Ryan McKenzie, of the US Fish and Wildlife Service, and Brian Mahardja, of the US Bureau of Reclamation, determined that electrofishing resulted in better detection rates for many native and non-native species than net-based surveys. Although electrofishing is currently restricted to freshwater areas of the Estuary and is more selective of larger fish and those with swim bladders, McKenzie and Mahardja recommend that resource managers employ the technique more widely to...
Read More

The robust monitoring programs established to track now-rare Delta smelt could benefit other native fishes, too.

Decades ago, resource managers first learned of declining Delta smelt numbers not through surveys targeting the once-abundant native fish, but rather as a byproduct of long-term monitoring programs for non-native striped bass. Now, the authors of a new study published in the March 2021 issue of San Francisco Estuary and Watershed Science advocate for the use of bycatch data from the recently established Enhanced Delta Smelt Monitoring (EDSM) program to better understand juvenile Chinook salmon distribution. “The scope of [this...
Read More

Fire Sparks Sewer Boon in Larkfield

Early on the morning of October 9, 2017, a firestorm roared with unforgiving speed across a swath of northeastern Santa Rosa. The unincorporated community of Larkfield lay directly in its path. One-hundred and sixty homes there burned to the ground. Three and a half years later, Larkfield is still being rebuilt—in some ways better than ever, thanks in part to an ambitious and innovative program by the Sonoma County Water Agency to bring sewer service to the modest, tight-knit community...
Read More

North America’s largest and most ancient freshwater fish species, white sturgeon, hang out in some kinds of Estuary waterways more than others, scientists find.

 Researchers with the U.S. Geological Survey found that adult and sub-adult white sturgeon occupy deep open-water channels and shallow open-water shoals in equal measure, but don’t use shallow wetland channels. As a group, white sturgeon are characterized as amphidromous, meaning they regularly migrate between freshwater and the sea, in both directions, but not for the purpose of breeding. According to the study, which appears in the December 2020 issue of San Francisco Estuary and Watershed Science, adults in the local...
Read More

Match Points in Stormwater Soup

Scientists studying environmental pollutants tend to divide them into two distinct groups. One includes “legacy” contaminants that drew attention during the early stages of the environmental movement, like mercury, PCBs, and some pesticides. The other is a much larger class of “emerging” contaminants whose production or monitoring began more recently and about whom less is known; think pharmaceuticals, plastic additives, and flame retardants. Effluent from wastewater treatment plants is often seen as the primary source of emerging contaminants in San...
Read More

Sacramento pikeminnow and introduced striped bass in the middle Sacramento River eat a surprisingly similar diet, says a new study in San Francisco Estuary and Watershed Science.

Both species have been implicated in the decline of vulnerable native species in the river, particularly juvenile Chinook salmon, says lead author Dylan Stompe, a PhD student and researcher at the University of California at Davis. For eight months in 2017, Stompe and fellow researchers with the California State University at Chico and the California Department of Fish and Wildlife surveyed a 35 kilometer reach of the river outside Chico for the two predatory fish. They baited hooks with with...
Read More

Squeezed by Geography

By Nate Seltenrich In most respects, Marin County is a privileged place. It ranks first in the Bay Area for income per capita and includes many of the region’s priciest zip codes. But its miles of Bay and ocean shoreline and many low-lying towns, positioned to afford easy coastal access and world-class scenery, represent a major liability in the era of sea-level rise. “Marin is the canary in the coal mine in some ways, because almost everything is in that...
Read More

A grassroots effort to move migrating newts across a Marin County road has drawn to a close, but organizers hope it leads to a more permanent solution.

For roughly half a mile, the two-lane road in a hilly rural area west of Petaluma travels alongside a large, natural body of water called Laguna Lake. On the other side is an oak woodland: the perfect place for California and rough-skinned newts, which spend the dry season in moist terrestrial habitat under leaf litter and wood debris or inside animal burrows. After seeing a number of native newts flattened along the road on rainy winter evenings, a small group...
Read More

Dennis McEwan finished work on the 430-acre Yolo Flyway Farms Tidal Habitat Restoration Project in September 2018. A month later, he retired.

The timing was no accident; he’d delayed his departure from the California Department of Water Resources (DWR) to see the project through after helping to launch it ten years earlier. But even from the very beginning of his career, McEwan had been committed to doing all he could for declining species in and around the Delta. That “calling,” as he put it, began with 25 years at the California Department of Fish and Game (now Fish and Wildlife) supporting Pacific...
Read More

Bob Fujimura spent his entire career with the California Department of Fish and Wildlife.

Bob Fujimura spent his entire career with the California Department of Fish and Wildlife. From 1987 until his retirement in late 2018, Fujimura served in a variety of roles at the department—but he is likely best known for heading up its long-term monitoring of native fishes in the Bay and Delta. Beginning in the mid-2000s, he oversaw annual smelt surveys with far-reaching implications for management and conservation, including the Spring Kodiak Trawl, which determines the relative abundance and distribution of...
Read More

An emergency barrier installed to protect the state’s water supply from saltwater intrusion during the recent record-setting drought had little effect on the ecosystem.

In spring 2015 the California Department of Water Resources dropped 150,000 tons of rock into False River in the Central Delta to halt encroaching tides that had little freshwater to hold them back. A few months later, it was clear the barrier worked, as salinity rose on one side and fell on the other. But what were the effects on local plants and animals? Through six overlapping yet distinct projects funded by the state Delta Science Program and NASA, and...
Read More

A small but mighty wetlands project on the San Rafael waterfront is moving forward thanks to a $1 million planning and design grant from the San Francisco Bay Restoration Authority.

Restoration of the heavily eroded 20-acre Tiscornia Marsh at the mouth of the San Rafael Canal will use dredged sediment to create new habitat for the endangered Ridgeway’s rail and salt marsh harvest mouse, migratory shorebirds, and other marsh species. Meanwhile, improvement of an adjacent levee will enhance public access along a levee-top section of the Bay Trail and, perhaps most critically, provide flood protection for the nearby Canal District, a dense, low-income community that’s home to many Latino immigrants...
Read More
1 2