WSP06933

• File Number: 8272.500
• Description: Colorado River Basin Salinity Control - Colo Dept of Public Health - WQCC and WQCD
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 11/1/1989
• Author: WQCD
• Title: Colorado Nonpoint Assessment Report - November 1989
• Water Supply Pro - Doc Type: Report/Study

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Effects of Nonpoint Source Pollutants ,

Metals

~ Numeric water quality standards have been established for toxic heavy metals
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eJf on all streams classified for. Class 1 aquatic life uses and for .many Class 2

aquatic life streams. The principal metals of concern are lead, zinc, copper,

and cadmium, but silver and mercury are also highly toxic. Many streams are

impacted by metals due to drainage from inactive mine adits, tunnels, and
. .

waste piles. Metals may result from natural sources throughout the Colorado

mineral belt as well. Elevated concentrations of metals, especially lead, .

have also been documented downstream from large urbanized areas in Colorado.

The primary concern resulting from metals concentrations, is the chronic or

toxic effect on aquatic organisms. The bioaccumulation of these toxic

substances in aquatic organisms may also affect higher .organisms in the food

chain; however, chemical and biological monitoring to date has not disclosed a

vegetative composition, .reducing suitability for habitat, and reducing the

natural assimilative uptake capacity of these valuable resources.

The Water Quality Control Commissionhaa adopted numeric water quality

standards for metals for,many streams throughout the state. The basis .for

these standards were typically "table"* values in cases where there was

evidence that ambient quality was better than the table criteria.

* "Table". value refers to the criteria listed in Table III of the Basic

Standards and Methodologies, 3.1.0 (5 CCR 1002-8) (Table 5 previous page).

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