The destructive environmental legacy of Gold Rush mining in the Sierra Nevada could last for thousands of years in the form of ongoing erosion of mercury-laced sediments, according to new research.
Mercury, a toxic heavy metal, was used in copious amounts in California's hydraulic gold mining operations in the mid- and late 1800s.
Miners blasted gold-bearing sediment out of vast, ancient gravel beds with water cannons. They then added liquid mercury to the slurry, allowing the gold-mercury amalgam to sink to the bottom of troughs.
But finer gold-mercury particles washed out of the mixture with the bulk of the sand and gravel. It has been estimated that between 3 million and 8 million pounds of mercury entered the environment from the hundreds of hydraulic gold mines that were operated in the Sierra before a court order banned the downstream deposition of mining debris in the region.
Researchers have long known that mercury-tainted sediment has made its way downstream all the way to San Francisco Bay, contaminating fish and wildlife and entering the food chain.
In a paper published online Monday in the Proceedings of the National Academy of Sciences, researchers tried to get a more precise idea of the deposition process.
They examined historical streamflow and topographical data in the Yuba River corridor and ran models to gauge sediment distribution downstream of old gold fields.
They concluded that large stores of undiluted mining debris remain in the river's floodplain -- a reservoir of contaminants that major floods can unleash and carry downstream for the next 10,000 years.
Given predictions that climate change will increase extreme weather events, powerful floods capable of eroding the mercury deposits could become more frequent.
Potent floods can "effectively deliver toxic sediment slugs downstream into sensitive lowlands, thus augmenting a major potential source of food web contamination" in the tidal wetlands of the San Francisco Bay estuary, wrote the authors, led by Michael Bliss Singer of the Earth Research Institute at UC Santa Barbara.
Related Article: AAPA Commends Leaders for Passage of Bipartisan WRRDA Bill
The American Association of Port Authorities (AAPA) lauded leaders of the House Transportation and Infrastructure Committee, leaders of its Water Resources and Environment Subcommittee and Speaker of the House John Boehner (R-OH) for their efforts in advancing H.R. 3080, the Water Resources Reform and Development Act (WRRDA). The House passed the legislation today by a vote of 417 to 3.
“AAPA commends T & I Committee Chairman (Bill) Shuster (R-PA), Ranking Member (Nick) Rahall (D-WV), Water Resources and Environment Subcommittee Chairman (Bob) Gibbs (R-OH) and Ranking Member (Tim) Bishop (D-NY), as well as Speaker Boehner, for their leadership in moving this crucial, bi-partisan legislation through the House so it can be conferenced with the Senate’s version and signed into law by the president,” stated AAPA President and CEO Kurt Nagle. “Our nation desperately needs new water resources legislation this year to fortify our infrastructure, create good-paying U.S. jobs, grow our economy and enhance America’s international competitiveness.”
Mr. Nagle noted that it’s been more than six years since Congress passed the last water resources bill…legislation that was intended to be reauthorized every two years.
“More than a quarter of America’s annual GDP is based on the value of goods that transit in and out of our ports. In order to keep our economic recovery progressing, we must ensure these goods can move efficiently, without avoidable and costly delays caused by inadequate or poorly maintained infrastructure,” he added.
Both the WRRDA bill passed today by the House, and the Senate version (S.601) which passed in May, have provisions that address a number of the needs of America’s seaports. In particular, the House version would:
- Set targets for increased use of federal Harbor Maintenance Tax (HMT) collections to better maintain the nation’s deep-draft shipping channels, while providing more equity for ports whose shippers pay more in HMT taxes than are required for maintaining those ports’ channels. WRRDA provides an important step in addressing this complex challenge.
- Give the private sector, as well as state and local agencies, more flexibility to advance funding for channel improvement projects by eliminating key roadblocks that non-federal entities must overcome when they want to contribute to project costs.
- Authorize and advance those federal channel improvement projects that have a completed Corps of Engineers’ Chief’s Report and that would otherwise be delayed without WRRDA, while complying with the House earmark moratorium.
- Revise Army Corps of Engineers procedures to accelerate waterside infrastructure projects and studies.
“By bringing WRRDA to the floor for a vote, Speaker Boehner, Chairmen Shuster and Gibbs, and Ranking Members Rahall and Bishop, have demonstrated they recognize the significant benefits more modern, efficient seaport and waterway infrastructure will have on our nation’s economic vitality, job growth and international competitiveness, as well as the value in helping address federal fiscal realities through sizable tax revenues provided by the cargo and trade activity moving through these systems,” Mr. Nagle said.“Increased investments are needed to better maintain and improve the transportation infrastructure on our three coasts and the Great Lakes, linking America to the global marketplace.”
He added, “America’s public ports – which create jobs for more than 13 million U.S. residents and handle 99 percent of our nation’s overseas trade – together with their private-sector partners are investing over $9 billion annually in marine terminal infrastructure. We look forward to a final water resources bill that results in the federal government upholding its end of this partnership by authorizing badly needed improvements to waterside connections with seaports.”
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