by Chris Larson
May 31, 2002

Washout! This road washout on Mattole Road on the way to Ferndale is an example of what happens when a culvert plugs. Photo: Amanda Malachesky

It’s hard to imagine on a nice summer day that the bottom of the river you see is not the same river bottom that was there a year ago. Older residents talk of forty foot deep pools in the river where only fifteen foot pools now exist. Fishing is what it used to be about, but now a once chilly river is warm enough for an enjoyable afternoon swim. These changes have all been caused by sediment – the thousands and millions of cubic yards of silt, sand, rock, debris, cobble and boulders that Mattole tributaries flush during each heavy winter storm.

Sediment is generated on the steep hillslopes of the Mattole. It can come from landslides, a natural feature of this unstable landscape. However, much of the Mattole’s sediment load is a result of roads, particularly roads that have failed or been abandoned. They are often unseen – after all, we usually drive only on maintained paved or dirt surfaces. But roads are out there and can be present in a density of over ten miles per square mile of the Mattole landscape.

Anyone who has been denied access to their home because the road to their place has failed can understand why roads are important, while those who are interested in fisheries restoration understand the central role that roads play in the Mattole’s woes.


TMDL Regulations and the Private Landowner

Enter a further reason roads are something to think about: Clean Water Act regulations, and specifically the Total Maximum Daily Load (TMDL) program.

The TMDL Program is a provision of the Clean Water Act of 1972 to address non-point source pollution. If there are still water quality issues after all specific sources of pollution are cleaned up, the TMDL process is begun. In the 1990’s, a coalition of non-Mattole California environmental groups sued the state to force the development of TMDL’s in rivers considered “impaired” by excessive sedimentation and high water temperatures. The resulting settlement directed the state to create a strict schedule to develop TMDL’s for almost every North Coast river. The Mattole River is listed for its temperature and sediment impairment, and the TMDL report is scheduled to be completed in 2002.

Once the report is complete, an implementation plan will be compiled and drafts will be available for public comment. The final implementation plan is scheduled to be completed by 2004. It will determine how long people have to address management-related sediment and temperature issues, and how much sediment runoff must be reduced.

In the Garcia River watershed, the first river to receive a TMDL implementation plan, sediment reduction will rely upon “voluntary compliance,” which means that landowners will be expected to voluntarily reduce the amount of management–related sediment produced on their lands.

The Mattole Restoration Council hosted two public forums about the TMDL process on May 8th and 9th. Representatives from the Regional Water Quality Control Board in Santa Rosa gave presentations about their work in the Mattole and fielded questions from Mattole landowners. In addition, a community panel consisting of Sterling McWhorter, a local rancher, Ellen Taylor, a local activist and environmentalist, ????????? from Pacific Lumber Company, and JJ Hall, an upper river resident, brought concerns, questions, and comments to the Water Board representatives.


Roads and Sediment

It is clear that most TMDL treatments will focus on road-related sediment. Whether they are abandoned or active, roads contribute an estimated 80% of sediment into the Mattole River. How do roads, a seemingly essential and no-frills technology, have such a grave impact on our river system? Two main design failures have been identified: improperly sized or maintained culverts, and the potential for diverting water out of natural drainages.

In high volume winter storms, a small creek can become a raging torrent carrying large debris. If a culvert is too small to carry all the debris, the creek jams up behind the culvert. A miniature dam has just been born, and water pools behind the culvert, eventually topping the road. In most cases, the fill that was placed above the culvert is washed downstream. On large roads in steep country, a single stream crossing might have up to 20,000 cubic yards of sediment above it. That’s enough to fill 2,000 dump trucks – an amount sufficient to line the road between Petrolia and the Mattole Grange!

Another difficulty with culverts is when they are placed at random intervals to carry water out of an inboard ditch. These culverts, termed “shotgun” culverts due to the way water shoots out of them onto the slope below, invariably cause gullies by concentrating a flowing stream of water on one place.

A second issue with roads is their ability to capture water running off of a hillslope in one canyon, and move it to the next. Each drainage exists in an equilibrium that took millennia to create. If too much water is diverted by a road from one drainage into another, the receiving drainage can be filled above its intended capacity, causing it to “blow out”.

The Mattole landscape is full of these and even more complex problems resulting from some combination of such design failures. And once a sediment source begins its erosion process, it becomes more and more difficult to stabilize and stop it.


Good Roads Lead to Clear Creeks

The presence of useful but perhaps ill-designed roads in this steep country, coupled with the high density of abandoned roads in the Mattole has resulted in its listing as sediment and temperature impaired. The creation of the Good Roads, Clear Creeks Program is in response to this reality. Through public funding, the MRC surveys and treats road-related sedimentation problems on cooperative private lands. Road treatments carried out through the Good Roads, Clear Creeks Program will help landowners meet TMDL requirements.

Most Mattolians don’t own the heavy equipment necessary for road upgrades and maintenance. Many don’t have the time to conduct surveys of their roads for potential problem sites. The Good Roads, Clear Creeks program offers these services to Mattole landowners as a way to reduce sedimentation of the Mattole’s watercourses, which has benefits to both landowners (who can demonstrate compliance with clean water goals), and to the fisheries (as the Mattole’s sediment load decreases over time, salmon habitat is improved.)

An example of the Good Roads, Clear Creeks Program in action is the Mill Creek watershed, a 2.1 mi2 sub-basin toward the coast from Petrolia. In 1999, the MRC surveyed all of the roads, landslides and streambank erosion sites within the drainage. Out of this survey, prescriptions were developed to treat sites that could potentially deliver additional sediment to the creek, river and ultimately, the estuary. This summer, the MRC will bring in heavy equipment and work crews to treat these sites at minimal cost to the participating landowners. The Council offers the Good Roads, Clear Creeks program on a sub-basin scale because of its interest in road improvements as a means to restore salmon habitat


Future Prospects and How to Get Involved

Even with the TMDL regulations, restoring the water quality of the Mattole to its namesake (Mattole means “clear water” in the native tongue) will take many years. However, it is never too soon to start, and the Council hopes to offer useful services to help landowners deal with water quality regulations proactively. The sooner our river contains more deep swimmin’ holes and thousands of spawning fish, the happier we all will be. For more information about the TMDL process, or to get on the list to receive a copy of the implementation plan for review, call the MRC office.



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Read more articles about TMDL

Table of Contents for Mattole Restoration Newsletter, Issue 18 - Summer/Fall 2002