Sunday, July 10, 2005

Gold Run Mercury

On July 8 I met Natural Resources Defense Council (NRDC) staff Gina Solomon and Miriam ? at the Dutch Flat exit on I-80, for a visit to the Gold Run Diggings. Gina and Miriam were making a follow-up to the NRDC team I led into the Diggings on May 19th of this year. The NRDC is interested in quantifying mercury contamination in the Diggings, and discovering how much mercury is discharged into Canyon Creek, and therefore, into the North Fork American River.

Land ownership in the Diggings is complex. Broadly, it is divided between public lands administered by the Bureau of Land Management (BLM), and 800 acres of private lands owned by Gold Run Properties (GRP). The GRP lands have been for sale for several years, the current asking price being ~$2.1 million dollars. The Diggings extend ~two miles south from I-80 to the rim of the North Fork canyon; BLM lands begin to appear about one mile south of I-80, and make the larger part of the Diggings near the rim of the canyon.

When Congress designated the North Fork a Wild & Scenic River (W&SR) in 1978, is created a special "Gold Run Addition" to the W&SR "corridor," extending more than a mile north of the river, into the southern part of the Diggings. The Dept. of Interior was instructed to purchase the private inholdings within the Addition, if the owners (GRP) were willing sellers.

They were not.

One of the GRP parcels within the Addition is a long narrow tract following Canyon Creek itself over the last mile of its course, to the North Fork. This is an old patented "tailings claim," such claims re-working the gold-bearing gravels which had already passed through the sluice boxes of hydraulic mines in the Diggings proper. It was called the Canyon Creek Placer Mine. Most of the historic Canyon Creek Trail is within this parcel.

By 1870, the regional pattern of consolidation of ownership of hydraulic mines was well under way at Gold Run. The days of individual ownership of small claims gave way to corporate ownership of large numbers of claims. The Gold Run Ditch & Mining Company (GRD&M) typified this pattern. It had the capital necessary to construct the huge drain tunnel from the Diggings to Canyon Creek. The GRD&M tunnel had two branches, beginning in vertical shafts, which branches converged into one giant tunnel, twelve feet wide and nine feet high. Three to five thousand cubic yards of tailings per day issued from the GRD&M tunnel into Canyon Creek, in 1881.

The slurry of gravel passed through sluice boxes of various descriptions, always "charged" with mercury. A single large sluice box might be charged with a ton of mercury, and a flask of a hundred pounds would be added every day; for the mercury, essential to capturing the fine gold, was constantly washing out the ends of the sluice boxes, and hence must needs be replaced.

Mercury is a kind of atomic glue, which attracts gold.

Hence mercury pollution on the grand scale afflicted every river and creek downstream from the hydraulic mines. The main forks of the rivers, the Sacramento River, the Delta, the San Francisco Bay, all were contaminated with mercury, and remain contaminated to this day.

All this was well known, but only in the last few years have serious efforts been made to stop the ongoing release of mercury into these same streams and rivers, from "point sources" in the old hydraulic mines. Usually, these point sources are regarded to be the drain tunnels. Drain tunnels are ubiquitous; there are several in the Gold Run Diggings, perhaps ten in the Dutch Flat Diggings, and so it goes, throughout the northern Sierra.

The NRDC, then, took water samples on May 19th, above the drain tunnels of the old GRD&M, in this same tunnel, and on Canyon Creek, both up- and downstream from the tunnel. Gina and Miriam were more or less repeating this same sampling regime.

On May 19th, following a series of heavy storms, an exceptional quantity of water was entering both shafts in the Diggings, and Canyon Creek was as high and muddy as I have seen it in many years.

On July 8th, very little water was entering either shaft, and Canyon Creek was clear and meek and mild, with a typical low summer flow.

It will be interesting to see what results are obtained from the July 8th samples; they should, I think, contrast sharply with the May 19th samples. My instinct is that the measure of mercury, in nanograms per liter, will be much less in the new samples.

However, just how they will contrast is debatable. Geologist Dave Lawler, very experienced in mercury contamination, suggests that the new samples may in fact show higher concentrations of mercury. That is, imagine if you will that a little pipe is discharging mercury into the GRD&M tunnel at a constant rate. First let one thousand liters per minute flow through the tunnel, and take a water sample at the outlet.

Then let ten liters per minute flow through the tunnel, and take a water sample at the outlet.

The quantity of mercury has not changed, but the quantity of water has decreased. Hence the second sample would show a higher concentration of mercury than the first.

To me, this model does not make sense; to me, the higher sediment load of the higher water flows should be directly correlate to the mercury load. So I expect much lower values of mercury concentration to come back, from the July 8th samples.

I am probably wrong. Time will tell.

Mercury contamination of both the BLM lands and GRP lands in the Gold Run Diggings is important, not only so far as continued pollution of Canyon Creek and the North Fork American (hence also, the Sacramento River, Delta, Bay and ocean), but as it may affect the chances of BLM acquisition of any part of the GRP lands.

It is my fondest hope that the BLM can acquire several hundred acres, at the least, of the 800 acres of GRD lands for sale. However, the BLM is, by rule, forbidden to acquire polluted property.

This rule is, perhaps, poorly defined. Recently the BLM acquired lands along the South Fork of the American. It is a certainty that the sediments--the gravel bars, etc.--on that part of the South Fork have mercury mixed into them, from gold mining in days gone by. However, there is no glaring "point source" to point to, as it were, so there was no obstacle to the acquisition, which will protect open space and public access along a very popular river corridor.

At Gold Run there are point sources of mercury. Just how bad these sources are is not well known. The NRDC sampling program will help us quantify the degree of mercury contamination there.

To my mind, mercury contamination at Gold Run is likely rather complex, and not easily reduced to a matter of a few drain tunnels. Each drain tunnel, for instance, had one or many "sluice cuts" leading into its upper end; such sluice cuts are very likely contaminated with mercury.

One could spend a million dollars cleaning up a tunnel, and the upstream sluice cuts would continue to bleed mercury into it, and through it

Canyon Creek itself, being worked as a tailings claim over the last two miles to the North Fork, is heavily contaminated with mercury. It is virtually impossible to clean up such a stream. For all its contamination, it has a rich complement of riparian vegetation, and is just crawling, teaming, with fish and garter snakes and Foothill Yellow-legged Frogs and all manner of aquatic life.

For that matter, the North Fork itself is heavily contaminated with mercury. It too is impossible to clean up. There may be quite a few tons of mercury in the North Fork, between Gold Run and Auburn. Of course, there is mercury upstream as well, from the mines in Green Valley, at Lost Camp, in Humbug Canyon, etc. etc.

Even the 49ers used mercury in their relatively tiny sluice boxes, long toms, and rockers. There is probably measurable mercury in North Fork sediments all the way up to the Royal Gorge.

To me, the open-space, scenic, and recreational values at stake at Gold Run, are of great importance. I hope the BLM can find a way to purchase the 800 acres of GRD land now for sale, despite its likely contamination with mercury. I am worried that a lot of money could be misspent, trying to remediate mercury contamination there.

Gina and Miriam enjoyed getting a look at the strange old shafts and tunnels and lovely, sparkling Canyon Creek. After they had finished gathering their samples, we made a short jaunt down the trail and across the little bridge to Waterfall View. There is still a nice bloom going on along the trail, with masses of Clarkia biloba and Monardella lanceolata.

Such is some recent news from Gold Run.

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