Spring and Shady Creeks: Mercury and Suspended Sediment

The Spring and Shady tributaries of the South Yuba River contain dozens of historic mine locations, the largest of which is the San Juan Ridge Mine. Mining operations in the area began in 1850 and have been more or less driven by the price of gold since that time. [1] In 1995, the San Juan Ridge Mine Corporation stopped gold mining operations following the breach of an underground aquifer that caused flooding and the overflow of containment ponds. [2] This breach released millions of gallons of mine waste into Spring and Shady creeks, drained and contaminated 12 local wells through the oxidation of naturally occurring heavy metals- including a well that supplied drinking water to a local K-8 school. [3] The mining company proposed to re-open their mine for gold extraction in 2012, which would require pumping up to 3.5 million gallons of groundwater to operate each day. [4] Pumping groundwater at this scale would likely deplete the underground aquifer that provides water to hundreds of community members. This could potentially cause serious impacts to surface water quality in Spring and Shady creeks due to increased surface flows from mining practices. 

To understand the present-day impacts to Spring and Shady creeks from legacy mining and to look at how increased water flow across a mine site may lead to decreased water quality downstream, SYRCL worked with the San Juan Ridge Taxpayers Association and The Sierra Fund to develop a sampling plan aimed at quantifying the annual sediment and mercury loads (or total annual amounts of mercury) in the system.

Figure 1: Mercury and TSS loads for the 2014, 2015, and 2016 water years

The mercury and total suspended solids (TSS) loads calculated for both Spring and Shady creeks demonstrate that there is a continued water quality impact from past mining activities. These results highlight the importance of remediating abandoned mine sites like the San Juan Ridge Mine. This study also provides us with data to support the concept that mines located on smaller tributaries have a cumulative impact on the watershed and places the water quality, habitat quality, and the health of the watershed at risk.

Contamination at this scale is compounded in the downstream direction, resulting in contaminated fish stocks, which impact public health and fisheries; and water quality impacts that reduce reservoir storage capacity and habitat health for aquatic organisms.

[1] Meals, Hank. 2012. History of Mining on Spring Creek and Shady Creek. https://www.sjrtaxpayers.org/wp-content/uploads/2012/09/HistoryOfMiningHankMeals.pdf

[2] Associated Press. 1997. Gold mine taints school’s water. The Register Guard 29 December 1997: 3A. https://news.google.com/newspapers?nid=1310&dat=19971229&id=T01WAAAAIBAJ&sjid=7-sDAAAAIBAJ&pg=6858,7618085&hl=en

[3] Pogash, Carol. “Efforts to Revive Rich California Mine Hit Strong Resistance.” The New York Times, The New York Times, 22 Aug. 2014, www.nytimes.com/2014/08/23/business/energy-environment/a-clash-of-gold-and-water-in-the-california-pines.html

[4] Brenner, Keri. 2014 Locals Rally against Reopening the San Juan Ridge Mine. The Union, 26 Feb. 2014, www.theunion.com/news/local-news/locals-rally-against-reopening-the-san-juan-ridge-mine/