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Last modified
8/11/2009 11:32:57 AM
Creation date
8/10/2009 4:56:06 PM
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UCREFRP
UCREFRP Catalog Number
9343
Author
Greve, A. I., N. E. Spahr, P. C. Van Metre and J. T. Wilson.
Title
Identification of Water-Quality Trends Using Sediment Cores from Dillon Reservoir, Summit County, Colorado.
USFW Year
2001.
USFW - Doc Type
Denver.
Copyright Material
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<br />Table 3. Trace-element concentrations from cores taken in the arms of Dillon Reservoir, and the top 4 centimeters of the core <br />taken near the dam, August 1997, compared to Canadian Sediment Quality Guidelines <br /> <br />[Mercury data were not collected in arms of reservoir; shaded values exceed probable effect level (PEL); bold values exceed interim sediment-quality guide- <br />line (ISQG). but not PEL; cm. centimeter; n. not available; all concentrations are in micrograms per gram] <br /> <br />Guideline or Depth Arsenic Cadmium Chromium Copper Lead Mercury Zinc <br />reservoir arm (cm) <br />ISQG1 5.9 0.6 37.3 35.7 35.0 0.170 123 <br />PEL2 17.0 3.5 90.0 197.0 91.3 0.486 315 <br /> <br />Blue River upper arm 0-1 10.0 5.8 1 70 58.1 220 -- I 1.870 <br />Core DBU 1-2 9.6 4.6 86 59.6 218 -- 2,000 <br /> 2-3 11.9 5.0 I 89 70.6 237 -- I 2,100 <br />Blue River lower arm 0-2 11.0 5.6 70 63.1 219 -- I 1.960 <br />Core DBL 2--4 13.4 5.7 I 66 66.5 265 -- 1,850 <br />Snake River upper arm 0-2 11.2 5.0 I 69 128 516 -- 2,870 <br />Core DSU 2--4 14.9 3.6 66 140 510 -- 2.860 <br />Snake River lower arm 0-2 15.4 4.8 I 75 113 390 -- 3.170 <br />Core DSL 2--4 13.7 5.1 I 69 112 I 331 -- 3,150 <br /> I I <br />Tenmile Creek upper arm 0-2 16.5 4.8 88 74.9 413 -- 2,280 <br />Core DTU 2--4 I 20.7 4.4 ~ 70.9 468 -- 2.330 <br />Tenmile Creek lower arm 0-2 12.4 1_ 4.:~_ _ 90 75.4 231 -- 2,610 <br />Core DTL 2--4 12.7 3.3 84 77.7 232 -- 2,640 <br />Dillon Reservoir near dam 0-1 12.8 1.02 53 97.5 227 0.21 3.370 <br />Core DLN 1-2 13.2 1.07 74 101 238 0.22 3,120 <br /> 2-3 13.6 1.06 75 101 232 0.20 3,150 <br /> 3--4 15.4 1.06 80 112 181 0.14 4.260 <br /> <br />IConcentrations below the ISQG are not expected to be associated with any adverse biological effects. Concentrations between the ISQG and the <br />PEL represent a range in which adverse biological effects are occasionally observed (Canadian Council of Ministers of the Environment. 1999). <br />2Concentrations above the PEL are expected to be frequently associated with adverse biological effects (Canadian Council of Ministers of the <br />Environment. 1999). <br /> <br />commun., 2000). This finding indicates that there is <br />likely some atmospheric deposition in the drainage <br />area. Mercury also is commonly found in gold <br />deposits and therefore is a by-product of gold mining <br />operations (U.S. Environmental Protection Agency, <br />1994). <br /> <br />In addition to the gradual (monotonic) trends <br />observed for some trace elements, several had more <br />complex temporal variations including high concentra- <br />tions or spikes, indicating that loads into the reservoir <br />in the past may have been much higher over certain <br />periods (fig. 5). The most prominent of these spikes <br />was observed in the distribution of copper, lead, <br />manganese, mercury, and zinc and was estimated to <br />have occurred in the late 1970's and early 1980's. <br />Because of the importance of mining in the Dillon <br />Reservoir watershed, it was hypothesized that spikes <br />in trace-element concentrations could be caused by <br /> <br />changes in mining activities in the watershed. No <br />single change in mining operation or land use occurred <br />in the early 1980's that could explain the temporal <br />patterns in the cores. The number of mining claims <br />increased over this period due to an increase in the <br />price of gold; however, these claims were not actively <br />mined (Delbert Tolen, St. John Mine, oral commun., <br />2001). <br />Dissolved and total trace-element data from <br />streams emptying into the reservoir were used in <br />conjunction with streamflow data to determine <br />incoming and outgoing loads of trace elements to and <br />from Dillon Reservoir for water years 1997 and 1998. <br />The loads entering the reservoir in most cases were <br />much larger than those exiting through the Blue River. <br />This indicates that the reservoir acts as a sink for major <br />and trace elements (table 5). Generally, copper, iron, <br />and manganese had the largest percentages of the <br /> <br />14 Identification of Water-Quality Trends Using Sediment Cores from Dillon Reservoir, Summit County, Colorado <br />
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