Western Lake Survey Phase 1. Characteristics of Lakes in the Western United States. Volume 1. Population Descriptions and Physico-Chemical Relationships

摘要

A survey of 752 lakes in the mountainous areas of the western United States was conducted in fall 1985 by the U.S. Environmental Protection Agency in cooperation with the USDA-Forest Service. The survey was a stratified design with equal allocation among strata allowing population estimates of physical and chemical characteristics of lakes within the study area to be developed. The five subregions surveyed included California, Pacific Northwest, Northern Rockies, Central Rockies, and Southern Rockies. Almost 37% of the lakes in California had acid neutralizing capacity (ANC) 50 ueq/l, whereas only 4.6% of the lakes in the Southern Rockies had ANC 50 ueq/l. Only one acidic lake (ANC 0), associated with hot springs, was samples in the West. Ninety-nine percent of the lakes in the study area had pH values 6.0. Concentrations of many chemical constituents were low in western lakes compared to values measured in the Eastern Lake Survey. Over 26% of the western lakes had conductance measurements 10 uS/cmi the highest percentage of these dilute lakes was located in California. Evaluation of ion ratios and the relationship of base cations to ANC suggest that regional lake acidification has not occurred in the areas of the West.