Lake Water Quality Conditions Research Articles

Monitoring and assessment of a eutrophicated coastal lake using multivariate approaches

Multivariate statistical techniques such as cluster analysis, multidimensional scaling and principal component analysis were applied to evaluate the temporal and spatial variations in water quality data set generated for two years (2008-2010) from six monitoring stations of Veli-Akkulam Lake and compared with a regional reference lake Vellayani of south India. Seasonal variations of 14 different physicochemical parameters analyzed were as follows: pH (6.42-7.48), water temperature (26.0-31.28°C), salinity (0.50-26.81 ppt), electrical conductivity (47-20656.31 µs/cm), dissolved oxygen (0.078-7.65 mg/L), free carbon-dioxide (3.8-51.8 mg/L), total hardness (27.20-2166.6 mg/L), total dissolved solids (84.66-4195 mg/L), biochemical oxygen demand (1.57-25.78 mg/L), chemical oxygen demand (5.35-71.14 mg/L), nitrate (0.012-0.321 µg/ml), nitrite (0.24-0.79 µg/ml), phosphate (0.04-5.88 mg/L), and sulfate (0.27-27.8 mg/L). Cluster analysis showed four clusters based on the similarity of water quality characteristics among sampling stations during three different seasons (pre-monsoon, monsoon and post-monsoon). Multidimensional scaling in conjunction with cluster analysis identified four distinct groups of sites with varied water quality conditions such as upstream, transitional and downstream conditions in Veli-Akkulam Lake and a reference condition at Vellayani Lake. Principal Component Analysis showed that Veli-Akkulam Lake was seriously deteriorated in water quality while acceptable water quality conditions were observed at reference lake Vellayani. Thus the present study could estimate the effectiveness of multivariate statistical approaches for assessing water quality conditions in lakes.

Water Quality Assessment of Lake Manzala, Egypt: A Comparative Study

Lake Manzala is the largest Egyptian lagoon which is considered as one of the most important fishing sources in Egypt. The lake faces a lot of environmental challenges which affect its water quality status. The main objective of this study is assessing the water quality status of the lake using an appropriate Water Quality Index (WQI). Records for twelve water quality parameters during the period from August 2010 to August 2012 were collected from 11 stations in the lake and from 4 stations at the drains outlets. Two Water Quality Indices (National Sanitation Foundation WQI and Lagoon WQI) and a GIS tool were used to assess and spatially assign the water quality conditions of the lake. The results reveal critical water quality conditions for the lake. The eastern and southern zones of the lake have the worst water quality conditions, ranking as a Very Bad water quality status, according to L-WQI. While the western zone of the lake has the best water quality condition, which is Good, according to L-WQI. Bahr Elbaqar drain has the worst water quality status Very Bad, among the studied drains, which affect the water quality conditions of the lake, in particular the eastern zone of the lake. The worst water quality status of the lake was recorded in August 2011, according to both used indices. The spatial assigning of the lake water quality conditions ensures that the lake should be divided into different zones for fishing and other objectives. An urgent water quality management strategy should be implemented for the lake.

Recent water quality trends and a comparison to sediment-core records for two riverine lakes of the Upper Mississippi River basin: Lake St. Croix and Lake Pepin

Long-term water quality monitoring data from two riverine lakes in the Upper Mississippi River basin, Lakes St. Croix and Pepin, were analyzed to compare the long-term average water quality conditions and land use distributions, water quality trends and loads at lake inlets and outlets, trends from long-term versus short-term monitoring records, and the ability of paleolimnological cores to accurately infer lake water quality conditions. During the 1976–2004 period, the long-term average concentrations of nutrients, suspended solids, and chlorophyll-a were consistently lower at the Lake St. Croix inlet versus the Lake Pepin inlet, which drains a greater proportion of urban and agricultural runoff. Despite these differences, nutrient trends were similar at the inlets to both lakes; reductions in total phosphorus and ammonium concentrations were attributed to improvements in point source technologies, whereas increasing nitrate concentrations were attributed to both point source changes and nonpoint source increases. Despite improvements in several water quality variables, nitrate concentrations are increasing in both lakes, sediment trends indicate persistent nonpoint source inputs to Lake Pepin, and current total phosphorus concentrations remain well above pre-1950s levels in both lakes. Since urban development and agriculture are increasing in the Lake St. Croix and Lake Pepin Watersheds, continued point source regulation and additional nonpoint source control efforts will be needed to further improve water quality in these lakes. The 1976–2004 trends for most water quality variables were similar at inlet versus outlet sites on Lake St. Croix. Trends at Lake Pepin inlet versus outlet sites were less similar, but data availability limited the comparison to the 1993–2003 period. While the truncated data record highlighted short-term trends in both lakes, the full data record was most useful for exploring general patterns in water quality. Length of monitoring record affected our ability to detect trends at the inlets to both lakes, and altered the magnitude of detected trends. During the two decades of the 1980s and 1990s, paleolimnological estimates of retained phosphorus loads were similar to those estimated from recent water quality monitoring. These similarities support the use of paleolimnological approaches to infer past water quality conditions in Lakes St. Croix and Pepin.

Effects of Hypolimnetic Releases on Two Impoundments and Their Receiving Streams in Southwest Wisconsin

The effects of bottom water withdrawals were evaluated within and below two southwestern Wisconsin impoundments. Like many man-made lakes in the unglaciated area of Wisconsin, Twin Valley Lake and White Mound Lake were constructed during the late 1960s for flood control and recreation. Both impoundments, which are located in large agricultural watersheds, were originally designed to release cold bottom water with the intended goal of managing trout below the dams. However, recent water quality monitoring results revealed that the streams became degraded due to frequent dissolved oxygen criterion violations and excessive filamentous bacteria growths. Organic loading from the bottom discharges is the likely reason that trout stream habitat was not successfully created below the dams as originally intended. Despite the accelerated phosphorus removal from the long-term withdrawals, blue-green algal blooms continued to be a problem in both impoundments. While maximizing total phosphorus export can improve lake water quality conditions, discharge rates from these impoundments were found to be excessively high, resulting in disturbance of their thermo-structure and entrainment of nutrients into the surface waters. In 2005, we blocked the bottom gate at Twin Valley Lake and monitored water quality and thermal responses. As a result, lake and stream water quality improved significantly while the downstream fish community structure did not change. The impoundment thermo-structure was restored with well-defined hypolimnion and epilimnion. We conclude that managing impoundments is often a balancing act between seemingly disparate goals of achieving optimum conditions above or below a dam, with undesirable consequences often occurring if the focus is disproportionately on a single goal.

An Integrated Modeling Approach to Total Watershed Management: Water Quality and Watershed Assessment of Cheney Reservoir, Kansas, USA

Degradation of water quality is the major health concern for lakes and reservoirs in the central regions of the United States as a result of heavily devoted agricultural production. A vital key to the development of a reservoir management strategy is to identify nutrient loading that describes associated water quality conditions in reservoirs. This study integrated AnnAGNPS watershed and BATHTUB lake models to simulate actual lake water quality conditions of Cheney Reservoir, KS, and demonstrated the use of the coupled model for simulating lake response to changes in different watershed land use and management scenarios. The calibrated current-conditions model simulated in-lake reductions as much as 52% for TN, 48% for TP, and 70% for chlorophyll a due to conversion to native grass, and increases as much as 4% for TN, 9% for TP and 6% for chlorophyll a due to conversion of land from the Conservation Reserve Program (CRP) to cropland (15.5% of watershed). This model also demonstrated an increase in chlorophyll a (19%) as the lake sediment capacity was reached over the next century.

The satellite derived optical information for the comparative assessment of lacustrine water quality

The objective of this research is to define the support that can be derived from satellite optical remote sensing to monitor the trophic status of lake waters, even in the absence of corroborating in situ measurements. An analysis was conducted on Lake Garda (Italy), where sub-basins showing different water quality conditions can be delineated. For this purpose, two Landsat-TM images, taken in April and August 1985, at specific seasonal situations of the limnological cycle were used. Image processing provided radiance-derived quantities, such as reflectance and chromaticity, in the form of digital transects drawn from the margin of the lake to cross the pelagic environment. In order to make the multi-temporal analysis possible, a method for compensating the differential haze effect between the two images, based on the darkest object technique was adopted. Results demonstrated the suitability of satellite remote sensing observations as a fast and relatively low cost effective tool for early and expeditious assessment of both the spatial and temporal variability of lake water quality conditions.

A Sensitivity and Error Analysis Framework for Lake Eutrophication Modeling1

ABSTRACT: A framework for sensitivity and error analysis in mathematical modeling is described and demonstrated. The Lake Eutrophication Analysis Procedure (LEAP) consists of a series of linked models which predict lake water quality conditions as a function of watershed land use, hydrolgic variables, and morphometric variables. Specification of input variables as distributions (means and standard errors) and use of first‐order error analysis techniques permits estimation of output variable means, standard errors, and confidence ranges. Predicted distributions compare favorably with those estimated using Monte‐Carlo simulation. The framework is demonstrated by applying it to data from Lake Morey, Vermont. While possible biases exist in the models calibrated for this application, prediction variances, attributed chiefly to model error, are comparable to the observed year‐to‐year variance in water quality, as measured by spring phosphorus concentration, hypolimnetic oxygen depletion rate, summer chlorophyll‐a, and summer transparency in this lake. Use of the framework provides insight into important controlling factors and relationships and identifies the major sources of uncertainty in a given model application.