Water-Resources Investigations Report
by W. Reed Green
This document is available in Portable Document Format (PDF): WRIR93-4218 (629 KB)
To view this document, you need the Adobe Acrobat® Reader installed on your computer. (A free copy of the Acrobat® Reader may be downloaded from Adobe Systems Incorporated.)
Water quality of the Maumelle and Winona water supply reservoir systems in
central Arkansas, was assessed on the basis of the data collected from May 1989 through October 1992. Water quality
relative to: (1) suitability for municipal water supply; (2) other streams and reservoirs within the region; and for the Maumelle reservoir, (3) the ecological trophic condition and sensity to change. The Maumelle reservoir covers 8,900 acres and is relatively shallow (maximum depth is 45 feet). The Winona reservoir covers 1,240 acres and has a maximum depth of 100 feet.
The tributary and reservoir water was analyzed for constituents regulated by the U.S. Environmental Protection Agency and the Arkansas Department of Health.
In many cases, the concentration of these constituents was at or below
detection limits, which was well below the respective maximum contaminant levels
used by the Arkansas Department of Health. Total iron and manganese concentrations often exceeded the maximum contaminant level, especially in the bottom of Maumelle. Turbidity levels also exceeded the maximum contaminant level, but this would be expected in the raw water.
The water quality of Maumelle and Winona reservoir systems also compared favorably when measured against other regional streams and reservoirs. From
these comparisons, it can be considered that the water quality of the
major tributaries discharging into the respective reservoirs represents the baseline or pristine condition within the region. Likewise, the water quality of the reservoirs could be considered to represent the baseline condition; Maumelle for a shallow, impounded flood-plain reservoir, and Winona for a deep river valley reservoir.
Data from the Maumelle reservoir system were used to investigate
trophic condition using empirical models developed from an 80 lake cross-sectional data set
that examined, specified, and parameterized trophic state relations.
Observed and predicted values generated from empirical trophic state models compared
favorably. The Maumelle reservoir can be considered in a state of
oligo-mesotrophic transition. If nutrient inputs can be maintained at current
levels, the water quality of the Maumelle reservoir should remain relatively stable.
However, increases in phosphorus load may alter the water quality from its present oligo-mesotrophic condition to that of a more eutrophic condition,
and this trophic response may be amplified with increases in nitrogen loading.
Abstract
Introduction
Purpose and scope
Description of study area
Maumelle reservoir
Winona reservoir
Study methods and approach
Hydrologic setting
Thermal and dissolved oxygen dynamics
Water quality related to municipal water supply
Water quality related to other regional streams and reservoirs
Regional streams
Regional reservoirs
Water quality of Maumelle in relation to trophic state and sensitivity to change
Summary
Selected references