Mattole Estuary

The Mattole estuary in winter 2005.  Photo: Amanda Malachesky

The Last Zone to Heal: Investigations in the Mattole Estuary

By C. Moss, Mattole Ecological Education Coordinator
It's a beautiful day in September and Honeydew  School students are at the estuary, monitoring water quality parameters, taking photo points, inventorying aquatic macroinvertebrates, and collecting estuary plants to press and identify. The river's mouth is still closed.

Fast forward to late October. This time the day is gray and foggy and the estuary has a stark, monochromatic beauty. The mouth is now open, thanks to some fall rain, and the shrill cries of seagulls are a counterpoint to the muted atmosphere the fog brings. Triple Junction High School students are spread out along the shore, monitoring water quality and taking photo points. Dissolved oxygen levels have dropped over the past month, as have temperature and water clarity.

Jump to November. David Simpson, Mattole Salmon Group board member and lifelong restorationist, is engaged in a Q & A session with Honeydew School students. Most of their questions are focused on the estuary. What are the major changes you've seen in the estuary since you started doing restoration work? What are the estuary's main problems? How can we help heal the estuary? Why is 'Rockzilla'-the big rock and wood structure in the estuary-there? Why don't you guys dredge out the estuary to remove sediment?

All good questions, says David, and complicated to answer.....Over the next hour, he gives the students a great synopsis of the historical antecedents to the problems in the estuary and watershed. He approaches the subject from a systems perspective, helping the students understand how a number of interconnected factors contribute to the degradation of a river, an estuary, a watershed, as well as to the healing process.

In one of the most compelling points of his discussion, David tells the students how 30+ years ago and new to the watershed, he was reading a book called Topsoil and Civilization. This book talked about how many of the great civilizations of the past unraveled as their watersheds and rich estuarine deltas degraded due to erosion stemming from overgrazing and overlogging. As David looked through his windows at the estuary spread out below, he had one of those proverbial 'Eureka!' moments. The Mattole's estuarine delta, once a rich and fertile zone, was a shallow, gravelly mess due to many of the same processes that have repeated themselves over the millennia. As George Santayana once said, "Those who do not remember the past are condemned to repeat it."

Estuaries are incredibly rich ecological realms, and as transitional zones-for salmon and many other species-they function as nurseries, filter systems for pollutants and terrestrial runoff, and crucial habitats for many aquatic species. Humans have been drawn to rich estuarine locations for thousands of years. In our own time, 22 of the world's 32 largest cities are located along estuaries.

Estuaries are getting a lot of attention lately because so many of them are under threat, largely due to negative impacts from human presence. Throw in the wild card of global climate change impacting ocean levels and tidal action, and the world's estuaries-large and small-are under siege.

Thanks to a recent EPA-Estuary grant awarded to the Mattole Salmon Group, with subcontract funding for various MRC programs-including MEEP-Mattole watershed students are now getting more familiar with their own estuary and its challenges.

In addition to the water quality and habitat monitoring mentioned above, this past fall Mattole students visited a restoration site just above the estuary, where a semi-permanent gravel bar that had formed over the years was causing constriction of the river's flow, particularly during the rainy season's high-flow times. David Simpson described how, in an effort to broaden the river's channel and lessen the erosive effects caused by the constricting gravel bar, thousands of cubic yards of gravel and cobbles were excavated and wing deflectors were put in at the base of the eroding bank to redirect the flow of water. It'll take the rainy season to see how successful this project is. Meantime, though, the landowner's bank was recontoured, mulched, and seeded. Mattole School students set up revegetation-monitoring plot grids, inventoried newly emerging grass shoots, took photo points, and will return over time to continue their monitoring and see how the site heals.

These same students will also plant trees in the estuary, later in November. Some day, hopefully, they'll be able to look down on the delta-much as David Simpson did, years ago-and rather than degradation, see an alluvial plain in the process of healing itself, thanks to their efforts and the efforts of countless other folks in the watershed's restoration community.

The Mattole Estuary in Photos

November 2009

Rain has finally returned to the Mattole after a long dry season. The lack of rain during the summer causes the estuary to form a lagoon, closing off ocean access to the river system. This year, the mouth opened on Oct. 14th. The season of the Mattole River mouth opening is celebrated by locals as adult salmon make their way back into the river to spawn.

Photo: Flora Brain
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November 2009

The Mattole River estuary from a lower vantage point than the above photo, revealing an extensive riparian forest.  The predominantly willow and alder forest that surrounds the south side of the estuary provides habitat for a variety of mammals and birds and contains remnant stream channels of the Lower Mattole River.  While these remnant channels have not contained the main flow of the river for some years, they sometimes still become flooded during winter flows, providing a complex ecosystem for all that reside in the estuary.
Photo: Flora Brain
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October 1972

The riparian forest shown in the above photo is not present in 1972. Instead, a wider channel exists and small patches of willow, alder, and coyote brush are beginning to take hold in the lower right corner. With winter rains, the river's sediment load increases, making the river a murky brown color, as seen here.  The mouth of the Mattole has opened with the rain and once again meets the ocean.
Photo: Kenneth and Gabriel Adelman

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June 1987

The riparian forest present today in the Mattole      estuary has fully developed, providing more complex habitat and hiding the remnant stream channels present in the 1972 photos.  Taken in June, this photo shows a much clearer river than the above photo, indicating that winter rains have not yet begun.  The river's mouth is still closed here and the estuary is temporarily transformed into a lagoon.
Photo: Kenneth and Gabriel Adelman

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February 2008

A young male sperm whale washes up on the beach a few hundred feet south of the river mouth.  Weighing in at 13 tons and measuring 32 feet in length, it was the second of its kind to wash up on the North Coast in a span of 3 weeks.  Researchers from Humboldt State University's Vertebrae Museum were unable to determine the cause of death.  The whale gradually decomposed, providing a massive food source for estuarine birds and mammals.

Photo: Flora Brain

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If you have estuary photos that you'd like to add to our collection, please contact us!

Mattole Forests

Forests

The Mattole River watershed is largely a forested landscape, with several different forest ecotypes present: redwood, Douglas fir, mixed hardwood, oak woodlands, Sitka spruce, tanoak, and mixed conifers.

Some of the dominant hardwood trees include California Buckeye (Aesculus californica), Oregon White Oak (Quercus garryana), several Live Oaks (Quercus spp.), Pepperwood (Umbellularia californica), Tanoak (Lithocarpus densiflorus), Madrone (Arbutus menziesii), and, in riparian areas, Red Alder (Alnus rubra), Oregon Ash (Fraxinus latifolia), Elderberry (Sambucus spp.), Bigleaf Maple (Acer macrophyllum), Vine Maple (Acer circinatum), Dogwood (Cornus spp.), and several species of Willow (Salix spp.).

TAN OAK

While the forests of the Mattole are diverse, three species stand out in the economic history of the place: tan oak, Douglas fir, and coastal redwood. The bark of tan oak was harvested in the late 19th century for its high tannin content. Tannic acid was necessary in the process of leather making. Most if not all of the harvested material was taken out by ship, from the mouth of the river near Petrolia.

Right: Tan bark piles before export from Petrolia in 1907. Photo courtesy of the Mattole Valley Historical Society.

RIPARIAN FORESTS

Riparian forests, those that grow along creeks and the River, are important to fisheries and riverine health as well. A healthy riparian canopy shades the watercourse and maintains cool water temperatures. In many coastal rivers, summertime water temperatures approach levels high enough to be lethal to salmonid fishes. Riparian zones act as a "buffer" between upslope lands and the river. This can work to prevent excessive nutrients and sediment from entering watercourses. Riparian vegetation also "armors" stream banks so that they can withstand high stream flows lessening the chance of eroding the banks. Fallen riparian vegetation (particularly the larger and more rot-resistant conifers) also contribute large woody debris to the river, which is important in the creation of complex habitats preferred by young salmonids.

CONIFERS

In the Pacific Northwest of the 20th century, particularly in the post-World War II construction boom, harvest of redwood and Douglas fir has become economically important. Douglas fir is the dominant forest species in the Mattole watershed. Prior to World War II, the technology did not exist to make harvesting and transporting of logs out of the extremely steep and rugged country of the Mattole profitable. After the war, two conditions were in place to make logging of Douglas fir in the Mattole a reality: a standing-timber tax that made it economically difficult for private landowners NOT to cut trees, and the tank tread technology and heavy equipment needed to make roads and transport logs out.

From the time of the migration of Eastern settlers to the watershed, land in the Mattole was held in large tracts primarily for ranching and orchard agriculture. The standing-timber tax forced much of the ranching community to either log their land or lose it. In 1957, Humboldt County had more sawmills than any other county in the United States. So many logs were being transported out of the Mattole that log truck drivers had to time their trips to the mill as to avoid congestion on the small roads. In the 1980s, most of the original forest had been entered for harvest, and very little ancient forest remained.

In 1988, the Mattole Restoration Council created a map depicting the ancient forest cover in 1942 and in 1988. Below is a picture depicting old growth forests as of 1997, which shows that of the total Mattole forestlands, only about 9% remain as ancient forest. That percentage has since dropped to less than 8%. The MRC is actively engaged in efforts to preserve remaining old growth forests.

Mattole Geology

Geology

The Mattole watershed is located in one of the most geologically active spots in North America. Three tectonic plates meet offshore, the North American, the Gorda, and the Pacific, forming the Mendocino Triple Junction. This network of faults produces many earthquakes, including the large and devastating events of 1952 and 1992. To learn about recent earthquakes in the area, click here.

Rates of uplift in the King Range are among the highest anywhere in North America.

The Mattole watershed is underlain primarily by young sedimentary rocks, which are highly erodible and often incompetent - easily fragmented and cracked. Soils, which are primarily of the Atwell, Boomer, Cahto, Hugo, Josephine, Kneeland, Laughlin, Los Gatos, Mattole, Maymen, McMahon, Melbourne, Usal, Wilder and Zanone series, range in depth from less than a foot on rockier ridge tops to more than six feet in bottomlands.

Mattole Grasslands

Grasslands

Before Europeans arrived in California, grasslands looked very different then they do today. Perennial bunch grasses dominated grassland ecosystems. Bunch grasses can live up to 100 years, and are adapted to semi-arid summer conditions and geology that is unique to California ecosystems. Each year new shoots are formed out of a common fibrous root system. These bunch grasses, with their large and well-developed root systems, are excellent at holding soil on to hillsides.

Perennial grass species exist in patches in the Mattole, but have been largely supplanted by introduced annual grasses from Europe and Asia. Annual grasses complete their life cycle in one year. In the Mattole, this generally means winter and spring vegetative growth, followed by seed production in early summer. Annuals are essentially dormant through the driest parts of the late summer and fall. Because they die and dry up in the fall, annual grasslands pose a higher fire risk than perennial grasslands.

Research suggests that grasslands historically covered around 25% of the Mattole watershed. These grasslands are important economically, particularly for cattle and sheep ranching, and other agricultural operations.

Last year, the Mattole Restoration Council completed a project comparing the extent of grasslands in 1950 and 1998. According to this research, more than a third of the Mattole's grassland's have disappeared since 1950, primarily due to fire suppression which allows fir and brush to encroach on the prairie edges. To see the full report, look at centerfold of Newsletter #19.