Spartina eradication: Herbicides are their dirty little secret

This is a good news/bad news story about the eradication of non-native Spartina marsh grass and the impact it has had on the population of endangered California Clapper Rail:

  • Spartina alterniflora, Smooth Cordgrass.  USDA photo
    Spartina alterniflora, Smooth Cordgrass. USDA photo

    The good newsUS Fish & Wildlife has temporarily halted efforts to eradicate non-native Spartina (Spartina alterniflora) in the San Francisco Bay Area because the population of endangered California Clapper Rail has declined by 50% during the period of eradication efforts from 2005 to 2011. (1)  This problem was identified several years ago and was attributed to the lack of cover for the rail as a result of eradication of non-native Spartina, which grows more densely, taller, and doesn’t die back in winter as the native Spartina does. (2)

  • The bad news:  US Fish & Wildlife attributes this negative impact on the Clapper Rail population on the slow recovery of native Spartina (Spartina foliosa). 
    Spartina foliosa - USFWS
    Spartina foliosa – USFWS

    They do not acknowledge that non-native Spartina provides superior cover compared to the native species.  Nor do they acknowledge that non-native Spartina was killed with herbicides.  Therefore, they do not consider the possibility that the slow recovery of native Spartina may be attributable to the herbicides that were used to kill the non-native plant.  They also continue to claim that the recovery of the endangered California Clapper Rail depends upon the return of native Spartina, despite the overwhelming evidence to the contrary.  The California Clapper Rail is a sub-species of Clapper Rail; the Clapper Rail is abundant on the East and Gulf Coasts and not endangered perhaps because of the superior cover provided by Spartina alterniflora on those coasts. (3)  Based on these fictions, US Fish & Wildlife proposes a new strategy that will simultaneously eradicate non-native Spartina while intensively planting native Spartina.  (1)

We have been following the Spartina eradication project since 2011.  For the benefit of new readers, we will review the issues with a few excerpts from previous posts on Million Trees.

Spartina alterniflora:  Treasured on the East Coast, reviled on the West Coast

Spartina alterniflora (Smooth Cordgrass) is a species of marsh grass native to the Atlantic and Gulf coasts of the United States, where it is considered a valuable plant making important contributions to the coastal ecology:

  • Its dense growth provides protection against storm surge and “erosion control along shorelines, canal banks, levees, and other areas of soil-water interface.” (4)
  • It filters nutrients, sediments and toxins from the water that flows off the land before reaching the ocean, acting as a natural water treatment facility.
  • It provides cover and food for birds, mammals and marine animals that live in the coastal marsh.

Where Smooth Cordgrass has died back in its native range, the dieback has been considered a serious environmental threat:

  • In 2001 the Governor of Louisiana declared a “state of emergency” when Smooth Cordgrass declined and the state obtained $3 million of federal funding to study and hopefully reverse the decline.  This study resulted in the development of a method of aerial seeding of Smooth Cordgrass to restore declining areas of marshland. (5)
  • A similar, but smaller dieback of Smooth Cordgrass in Georgia led to a collaborative research and on-going monitoring effort by 6 research institutions in Georgia.
  • Similar dieback of Smooth Cordgrass has been reported as far north as the coast of Maine.  A researcher at the Connecticut Agricultural Experiment Station is quoted in that report as saying, “In New Orleans, if their marshes were intact, the storm surge of Katrina would not have reached the levees.” (6)

 The war on Smooth Cordgrass on the West Coast

Smooth Cordgrass is not native on the Pacific Coast of the United States.  Therefore it is treated as an alien invader to be eradicated with herbicides:

  • $24 million was spent to eradicate Smooth Cordgrass in San Francisco Bay and Willapa Bay from 2000 to 2010 (7)
  • $16.3 million is projected to be spent on the entire West Coast from 2011 to 2020 (7)

Spartina is being eradicated with an herbicide, imazapyr.  This is a new herbicide about which little is known.  The analysis that was done to justify its use in the Spartina eradication project admits that no studies have been done on its effect on shorebirds, including the endangered Clapper Rail. 

The Material Safety Data Sheet mandated by the Environmental Protection Agency tells us that imazapyr is “not readily biodegradable.”  So, in the event that we eventually learn that this herbicide is harmful to shorebirds and/or to us, we probably should assume that it will still be in the environment in the nearly 200 sites in the San Francisco Estuary on which it has been sprayed.  Imazapyr is also being sprayed–sometimes from helicopters–in hundreds of places along the West Coast, including Oregon and Washington.

Imazapyr is often mixed with glyphosate by the Spartina eradication project.  Glyphosate is a non-selective herbicide.  That is, it kills any plant it is sprayed on at the right stage of its growth.  But imazapyr is far more insidious as a killer of plants because it is known to travel from the roots of the plant that has been sprayed to the roots of other plants.  For that reason, the manufacturer cautions the user NOT to spray near the roots of any plant you don’t want to kill.  For example, the manufacturer says explicitly that imazapyr should not be sprayed under trees, because that tree is likely to be killed, whether or not that was the intention. 

Furthermore, no tests have been conducted on the toxicity of combining multiple pesticides in a single application.  Therefore, we know nothing about the possible synergistic effects of combining imazapyr and glyphosate. 

These facts about the herbicides used to eradicate non-native Spartina bear repeating.  The main herbicide being used is known to be mobile in the soil and persistent in the environment.  The herbicide with which it is often mixed is an indiscriminate killer of any plant on which it is sprayed.  Therefore, the likelihood that these herbicides will prevent the establishment of the new plantings of native Spartina should be taken into consideration.  The entire enterprise seems deeply flawed, both harmful and futile. 

Bringing it home to the Bay Area

So, what does this have to do with you?  If you are concerned about pesticide use, you might be interested in the fact the East Bay Regional Park District (EBRPD) used 203 gallons of imazapyr in 2009 and 121 gallons in 2010 for the sole purpose of eradicating Spartina on their properties.  We don’t know how much imazapyr EBRPD used in 2011, 2012 and 2013, because they haven’t published a report of pesticide use since 2010.  Since their properties are only on the east side of the San Francisco Bay, we should assume that at least that much imazapyr was used by land managers on the west side of the Bay.

 Displacement of Clapper Rails in San Francisco

California Clapper Rail.  British Wikipedia
California Clapper Rail. British Wikipedia

In July 2011, a Clapper Rail was seen and photographed at Heron’s Head in southeastern San Francisco.  There was quite a bit of excitement about this sighting because a Clapper Rail had not been seen in San Francisco for decades.  That excitement dissipated when we learned more about where this bird came from, which provided a probable reason for its arrival.

The Clapper Rail was wearing a radio collar that had been put on him and 109 other rails by the USGS to track their movements.  He had moved from Colma Creek, 11 km south of Heron’s Head, which is one of nearly 200 Spartina “control sites” in the San Francisco Estuary.  The bird sighted at Heron’s Head is one of three Clapper Rails that have left Colma Creek since 2007, when the radio collars were placed.  The Spartina control project has been going on for over 10 years, so we have no way of knowing how many Clapper Rails were displaced prior to 2007.  In 2012, non-native Spartina at Heron’s Head was sprayed with herbicides.  Where did the Clapper Rails go from there?  Was there anywhere left for them to hide?

Pesticide Application Notice, Heron's Head, 2012
Pesticide Application Notice, Heron’s Head, 2012

As our readers know, native plant advocates claim their “restoration” projects benefit wildlife.  They can offer no evidence for this claim.  But there is considerable evidence that proves them wrong.  The endangered California Clapper Rail is one such case.


(1)     Adam Lambert et.al., “Optimal approaches for balancing invasive species eradication and endangered species management,” Science, May 30, 2014, vol. 344 Issue 6187

(2)     “West Coast Governors’ Agreement on Ocean Health, Spartina Eradication Action Coordination Team Work Plan,” Released May 2010, page 12

(3)     Cornell Ornithology Lab:  http://www.allaboutbirds.org/guide/clapper_rail/id

(4)     “Smooth Cordgrass,” USDA/NRCS Plant Fact Sheet.

(5)  Dorset Hurley, “Geogia’s Marsh Die Back and Louisiana’s Marsh Browning,” Altamaha Riverkeeper

(6)  “What’s killing off our salt marshes,” Going Coastal Magazine, September 15, 2008

(7) “West Coast Governor’s Agreement on Ocean Health,” May 2010, page 5-6