Document Type

Technical Report

Publication Date



Progressive increases in concentration of dissolved solids in the Colorado River water from Lake Powell to Imperial Dam seem to alter plankton dynamics and biological productivity of the river. Also, changes in biological productivity and micronutrients concentrations occur within the same reservoir. Development of a digital simulation model to predict micronutrients concentrations and biological productivity is necessary for diagnosing changes in plankton population and effluent-carrying capacity of the system.

The objectives of the study are: (1) to determine trace metal balance at different locations in Lake Mead, (2) to measure biological productivity and conduct plankton population counts at each sampling location, (3) to derive functions relating biological productivity to trace metal concentrations, suspended sediments and some physical variables (temperature, light, solar radiation), and (4) to develop a mathematical model for predicting spatial and temporal changes in biological productivity, plankton dynamics and trace elements concentrations.

Data acquisition is limited to the identification of the principal parameters which relate to the biology and chemical properties of the aquatic system(s). The data is subjected to mathematical analysis to identify trends in spatial and temporal planktonic variabilities.

Extensive chemical and hydrodynamic studies have been attempted on Lake Mead. The United States Geological Survey publishes annually an extensive report containing water chemistry at Hoover Dam and Bright Angel Creek. Additional chemical data are collected by the Bureau of Reclamation and is reported in the following publication series: CHE-46 (1965), CHE-70 (1970), REC-ERC-71-11 (1971).

The Environmental Protection Agency (FWQA) has completed minor investigations on Lake Mead in their report of January 1967 and of October 1968.

These studies were performed in the light of the monumentous efforts of Anderson and Pritchard (1951) and Smith et al. (1954).

Hill (1965) draws a note of caution by his prediction of the quality of Colorado River water.

Outside of the limited work by the EPA and Moffett (1943), hydrobiology has been neglected.

This report constitutes the first integrated scheme of chemistry, hydrobiology and hydrodynamics. The original direction was to follow assumptions derived through our first zooplankton and chemical analyses of Lake Mead. At that time we felt that the chemistry data would indicate a sharp drop in primary productivity (PPR) from South Cove to Hoover Dam. Our zooplankton data, however, indicated that Boulder Basin was experiencing stress either chemically or biologically. The early chemistry study indicated the lack of certain required micronutrients across the system. We are satisfied that the PPR does drop from South Cove to Bonelli Landing; however, we did not expect the accelerated eutrophication covering the whole of Boulder Basin.


Aquatic ecology; Benthic organisms; Freshwater phytoplankton; Lake Powell (Utah and Ariz.); Limnology; Sedimentation and deposition; Trace elements in water; Water conservation; Water quality


Biochemistry | Biology | Ecology and Evolutionary Biology | Environmental Chemistry | Environmental Indicators and Impact Assessment | Environmental Microbiology and Microbial Ecology | Environmental Monitoring | Environmental Sciences | Fresh Water Studies | Microbiology | Natural Resources and Conservation | Natural Resources Management and Policy | Soil Science