Why logging the Woodfin watershed is a bad idea

By now, most Mountain Xpress readers have probably heard about the controversy concerning the Woodfin Water District’s proposal to log their 1,800-acre watershed to raise money for system maintenance and repairs.

There are many reasons why the people of Buncombe County might legitimately object to this plan. In this rapidly urbanizing county, green space becomes more scarce each day. From that perspective alone, it seems extremely shortsighted to log what may be the last 1,800-acre nonfederal tract of old-growth forest in the county. But what many may not realize is that there are grant programs that would pay Woodfin about what they could make from logging in exchange for putting the watershed into a conservation easement — which would permanently protect it from timbering activities. The state’s Clean Water Management Trust Fund, for example, was established precisely to address such situations.

Naturally, there is also considerable public outcry over the fact that the forestry consultant hired by the Woodfin Water District stands to make about $320,000 (8 percent of about $4 million) if he is successful in persuading the people and officials of the Water District to proceed with this logging plan. Many of those concerned citizens of Woodfin have seen firsthand the eyesore created recently when the Mars Hill watershed was logged under a similar plan drawn up by the same forester.

All these factual aspects of the situation are well-known, publicly documented and need no further comment here. As a water expert at Buncombe County’s public university, however, I feel a responsiblity to share what is currently known about the proposed logging plan’s potential implications for both water quality and quantity.

In seeking to objectively summarize this information, I have consulted extensively with my longtime colleague and mentor Dr. Dan Okun of UNC-Chapel Hill, who is internationally recognized as one of the leading water-supply engineers in the entire world. We agree on the following points:

1) Logging a maturely forested water-supply watershed will reduce the amount of water it can deliver — especially during periods of drought, when that water is most needed. After heavy rains, there will actually be more water discharged in the form of surface runoff. And until the newly planted trees achieve sufficient size (about eight years) they will use less water. But these increases will be noticeable for only a few days following a rainstorm. Otherwise, the amount of stream flow feeding the collection reservoir will be lower than it was for the mature forest.

The situation is similar to the difference between an urban and a rural watershed. In an urban setting, there’s a rapid increase in stream flow following a storm because of the increased amount of impervious surface (i.e. paved area). But after the surface runoff has ceased, the stream flow will be much less than in a rural watershed. In the case of the Woodfin reservoir, this means that with the forest canopy removed, much of that extra surface runoff will simply run over the spillway during wet periods and be wasted, and there will be much less flow into the reservoir during an extended drought period.

2) No matter how carefully it’s done, any significant removal of the forest canopy will dramatically increase the amount of soil erosion and sedimentation, compared to an undisturbed forest. At present, the Woodfin watershed has very low levels of erosion and sedimentation, so even if they increase about five-fold, as predicted, they will still be relatively low compared to many water-supply watersheds with more development and soil disturbance. But the average turbidity of the water will still increase significantly — which means that the sand filters at the water-treatment plant will clog faster and will have to be backwashed more frequently. This will somewhat reduce the amount of finished drinking water the plant can produce. Perhaps more importantly, the sand filters will wear out years sooner — and replacing them is very expensive.

The biggest potential cost threat, however, relates to the fact that the Woodfin watershed is now classified WS I (i.e. undisturbed) by the state. As a result, the Water District is allowed to simply sand-filter and disinfect its water. But additional turbidity caused by logging operations could easily trigger a requirement for a separate coagulation step — which would significantly increase both capital and operating costs for the system.

Of course, even over 20 years, it’s unlikely that those additional costs would amount to as much as the millions of dollars of profit that might be realized from the very extensive proposed logging. But if the same amount of money can be obtained through conservation-easement grants, the Water District wouldn’t have to pay those additional capital and operating costs, the water quality could be kept at its current high level — and Buncombe County’s largest remaining nonfederal forest would be preserved for our future generations.

For all the reasons just described, water-supply watersheds are being increasingly protected throughout the United States. The future of protecting public water supplies lies in producing mature, old-growth-forested watersheds — not in destroying them.

[Richard P. Maas is co-director of UNCA’s Environmental Quality Institute. He specializes in water-quality issues and is a former member of the Regional Water Authority of Asheville, Buncombe and Henderson.]