SURFACE WATER QUALITY 



Introduction 



Early 19th century explorers, fur traders, and 

 missionaries described the Clark Fork as a clear and pristine 

 waterway, teeming with life (Horstman 1984) . This vision of 

 the Clark Fork faded into a memory with the advent of mining 

 later in that century, as mining, milling, and smelting 

 wastes were dumped directly into Silver Bow Creek and 

 transported downstream. In 1872, James A. Garfield noted 

 that "the beautiful river has been permanently ruined by the 

 miners; and has been for three years as muddy as the 

 Missouri. Before the discovery of gold, it was as clear and 

 pure as any mountain stream could well be" (Horstman 1984) . 



The mining activities resulted in high concentrations of 

 heavy metals and high sediment loading in the river, and as 

 the basin became more developed, nutrient loading also 

 increased. Those early days of neglect resulted in a river 

 system that was virtually unusable and uninhabitable for fish 

 and other aquatic species. However, as environmental 

 awareness grew and ushered in the age of water quality 

 standards and regulations, conditions in the river system 

 began to slowly rejuvenate. Although it still has much room 

 for improvement, the river has nonetheless staged a rather 

 dramatic comeback. 



The following sections touch briefly on historical water 

 quality (pre-1984) in the Clark Fork and then describe recent 

 and current water quality conditions (1984 to present) in 

 detail. This latter section focuses on heavy metals 

 (particularly copper and zinc) and suspended sediments, as 

 these are the parameters of greatest concern today. Other 

 surface water quality problems, such as ammonia, dissolved 

 oxygen (DO), elevated temperature, color, foam, etc., are 

 discussed in less detail. Nutrients, an important issue in 

 the basin, and their effects on algae growth are discussed in 

 the section following surface water quality. 



Historical Surface Water Quality Problems 



One of the first comprehensive studies of water quality 

 degradation in the Clark Fork drainage was conducted in the 

 late 1950s by the Montana State Board of Health to obtain 

 information necessary for the classification of streams and 

 the establishment of water quality standards. This study 

 (Spindler 1959) involved a comprehensive chemical and 

 biological survey of the entire mainstem and major tribu- 

 taries. After publication of that report, there was little 

 activity on the river until the 1970s, when several studies 



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