Laserfiche WebLink
<br />I <br /> <br />1783 <br /> <br />Copper <br /> <br />Median dissolved-copper concentrations increased about 100 percent between Leadville and Malta during <br /> <br />the pre-snowmelt, snowmelt, and post-snowmelt runoffperiods because of substantia! copper loading from Califor- <br /> <br />nia Gulch and nonpoint sources (fig. 8). The median dissolved-copper concentration in California Gulch was 8 J.lW <br /> <br />L. The dissolved-copper concentration in unpolluted freshwaters typically ranges from 0.5 to I J.lg/L. Dissolved- <br /> <br />copper concentrations tended to remain relatively constant downstream from Malta to about Parkdale, where they <br /> <br />decreased substantially (fig. 8) because of increased partitioning of copper to the particulate phase. The percentage <br /> <br />of copper in the dissolved phase ranged from about 50 to 75 percent between Leadville and Parkdale, but decreased <br /> <br />to almost 30 percent at Portland (fig. 9). Dissolved-copper concentrations were not diluted between Malta and Gran- <br /> <br />ite by the substantial tributary inflow from Lake Creek because of somewhat elevated dissolved-copper concentra- <br /> <br />lions (2 to 3 J.lg/L) in Lake Creek. Seasonally, the median dissolved-copper concentrations were largest during <br /> <br />snowmelt runoff (fig. 8), which is somewhat unusual, because dissolved trace-element concentrations are typically <br /> <br />inversely proportional to streamflow and are diluted by increasing streamflow. It's very likely that colloidal copper, <br />'hiCh will pass through a 0.45 J.LIIl filter, increased during snowmelt runoff (Kimball and others, 1995). <br /> <br />. ..~~l~~1.;iI~NAt D~~~~~' <br />'>"':!,~~a..."IU" <br />,,;;,~ S b'act to Revision ~ <br />'""\ ~T bUOiE OR RE.U:.~S~ <br />i,,0 NO I by Dlrec.CI, <br />.. \',ng Approvo <br />,'5(;0 . . ; (II Surve'{ <br />U 5 O"-o:oo"c.. . <br />._. 'OJ wi <br /> <br />I <br /> <br />23 <br />