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.