Implementation

In 1998 JMU Chemistry, Dept. Downey Lab estimated that 125 tons of limestone sand introduced into the upper reaches of St. Mary's River and its tributaries would provide five years treatment to offset the effects of acid deposition. This estimate was based on existing stream water chemistry, annual rainfall, stream discharge and acid loading. After reviewing the data from the first liming, in 2004 it was proposed that 200 tons of limestone was needed for a five to seven year treatment. The limestone was distributed to six locations within the Wilderness by helicopter in March 1999 and seven locations in November 2005 (Table I). The stream sites with greater discharge and lower pH received more limestone than those of lower discharge and higher pH. A total of 140 and 230 tons were actually distributed in 1999 and in 2005, respectively. At all the liming sites limestone was placed far enough upstream to treat the maximum length of each stream, yet not at sites of intermittent flow. Stream gradient was generally 2-5%. The limestone placed at these sites moved downstream due to the flow of the stream water and incorporated into the substrate to form treatment zones of 150-250 meters. As

found for other stream liming projects we have designed, it was intended that the limestone would slowly dissolve as stream water flowed over the substrate to provide a "timed release" treatment. More than 10 miles of stream were thus treated within the Wilderness Area.

Table I: Limestone sand allocations in the St. Mary's Wilderness. \

Site 1st Liming 2nd Liming Upper St. Mary's 50 75 Hogback Creek 25 36 Chimney Branch 15 26 Bear Branch 20 30 Mine Bank Creek 15 24 Sugartree Branch 15 23 Northern Tributary 0 16 Total 140 230

Figure 1: Map of St. Mary's Wilderness showing the St. Mary's River and its major tributaries. Approximate locations of 2005 liming sites are indicated (ø). (Map courtesy of United States Forest Service).

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