Evaluation Of River Water Quality Research Articles

Evaluation of river water quality using multivariate statistics and water quality indices: A case of Göynük canyon (Turkey)

Natural and anthropogenic water pollution caused by heavy metals has become a major problem worldwide. As a result of these processes, many harmful heavy metals are mixed into the water and endanger the environment and human health. Therefore, this study aimed to investigate the hydrogeochemical properties of the stream waters of Göynük Canyon (Göynük Stream), which is located in southern Turkey, an important touristic region of Antalya. A total of 44 water samples were retained to evaluate the geochemical type, heavy metal contamination level, and suitability for drinking and irrigation of Göynük Canyon Stream waters. All samples were analysed by inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence (XRF), and multi-parameter portable water quality assessment.Analysed water samples were found to be of classes II and III in terms of overall water quality. The average hardness level is above the limit values. The results of geochemical analyses showed that the common water types in the region are Mg–Ca–HCO3, Ca–Mg–HCO3, Ca–Mg–HCO3–SO4, and Ca–Mg–HCO3–Cl-water facies. Most of the samples belong to the "rock weathering dominated" region represented in the Gibbs diagram. The hydrogen ion concentration (pH), electrical conductivity (EC), and total dissolved solids (TDS) values vary between respectively 6.5–7.9; 230.4–720.8 μS/cm, and 149–468 mg/L. Cations and anions followed the order Ca2+ > Mg2+ > Na+ > K+ and HCO3− > SO42− > Cl− > F− > NO3−. Heavy metal anomalies in water followed an increasing order: Cu < As < Pb < Ni < Ba < Fe < Cr < Mn < Zn < Sr. These heavy metals showed high index values (Poseidon index (PoS), contamination factor (CF), enrichment factor (EF), geochemical index (Igeo), heavy metals pollution index (HPI), contamination degree (Cd), in some water samples. There is a spatial anomaly in these locations related to limestone and ophiolite. This water can be used for irrigation purposes according to Wilcox, the United States salinity laboratory diagram (USSL), permeability index (PI), Kelly's ratio (KR), and Residual Sodium Carbonate (RSC).

Identification and quantification of nutrients sources in the Aspio watershed (Italy). Insight from geogenic mineralization and anthropogenic pressure

An accurate evaluation of river water quality could be challenging due to the complex hydrological and anthropogenic processes which affect its nature. Reliable water quality data are mandatory to identify long-term trends and regional variability at the watershed scale. In this study, a combined approach using time series, regression, and multivariate statistical analysis along with SWAT modelling was applied to identify the relevant hydrogeochemical processes and the nutrients sources within the Aspio watershed (Ancona, Italy). The analysis detected different processes: i) the geogenic origin of Cl- and SO42-, ii) the heavy metals (Cu and Ni) and hydrocarbons pollution due to runoff from urban and industrial areas, and iii) the agricultural contribution of pesticides, nitrogen, and phosphorous. A SWAT model was implemented to quantify the nutrients load in the Aspio river. A calibration for streamflow, river sediment yield, and for nutrients load was obtained considering agricultural, urban, and wastewater treatment plant contributions. Agriculture and treated wastewater contributed to the overall nitrogen load only for 4% and 12% respectively, while the majority was due to leakage from urban sewage (84%). A scenario with only fertilizers’ load (excluding other sources) highlighted that nitrogen and phosphorous export from agricultural lands did not significatively impact the Aspio river. The spatial representation of runoff susceptibility also showed how the highest susceptibility for nitrogen and phosphorous loads is due to areas located close to urban settlements.

Research on river water quality evaluation based on the GA-PP and improved fuzzy model.

To ensure the water quality of rivers, it is crucial to scientifically evaluate their water quality status. This study takes a river in Jiangsu, China, as an example to establish six targeted main indicators for river water quality evaluation and uses a projection pursuit model optimized by the genetic algorithm to determine weights. Applying the improved fuzzy evaluation model to the final evaluation of water quality, the results indicate that this article adopts a weight calculation model that reduces dimensionality without losing data features, and the comprehensive evaluation model is also more complete, resulting in more accurate evaluation results. According to model analysis, the summer water quality is good and peaks from June to July. This article proposes corresponding measures and suggestions in response to the reasons behind this seasonal change. The evaluation model used in this article is superior to other models in terms of accuracy and portability, making it an excellent choice for river water quality evaluation. It can provide valuable technical guidance for similar river water quality evaluations.

Water quality assessment of the Nam River, Korea, using multivariate statistical analysis and WQI

Water quality assessment using water quality index (WQI) is performed based on major variables reflecting the river characteristics. We evaluated the water quality of tributaries of the Nam River in South Korea. We analyzed the tributaries spatial characteristics using cluster analyses and selected the main water quality variables (Cluster 1: chemical oxygen demand [COD], total organic carbon [TOC], total nitrogen, and total phosphorus; Cluster 2: water temperature [WT], dissolved oxygen [DO], COD, and TOC; Cluster 3: WT, DO, electrical conductance, COD, and TOC) of the clustered rivers. The WQI for each tributary was calculated using variables selected post statistical analysis. We verified that the WQI calculated in this study was similar to the annual change in water quality of the target river. Finally, it was analyzed that performing river water quality evaluation using the major variables selected using statistical analysis reflects the current water quality status of the river in more detail. (WQI grade was S1 Good (63.0), S2 Poor (53.3), S3 Excellent (98.4), S4 Poor (48.4), S5 (Excellent (100.0), S6 Good (77.6), S7 Good (76.2), S8 Good (76.5), S9 Good (69.9), S10 Excellent (81.5), S11 Good (71.2), S12 Good (63.1), and S13 Good (63.5).) Our method effectively reduced the number of variables required for index calculation compared with WQI methods of the MOE. Further, the reduced number of variables simplified the analysis process, reduced analysis time, and enabled water quality assessment that reflected the water quality characteristics of the river to be evaluated.

Evaluation of river water quality in a tropical South Sumatra wetland during COVID-19 pandemic period

&lt;abstract&gt; &lt;p&gt;The COVID-19 outbreak affected the world badly in this 21&lt;sup&gt;st&lt;/sup&gt; century leading to the closure of all types of anthropogenic activities. It is declared that there was an environmental betterment in names of water quality and air quality during the COVID-19 period. In this study, we analyzed the improvement in water quality by evaluating the suspended particulate matter (SPM) using the remote sensing technique in a tropical South Sumatra wetland i.e., Musi River in Southern Sumatra, Indonesia. The SPM values were estimated from Landsat 8 images Level-2 product. A quantitative and spatial analyses of before (20&lt;sup&gt;th&lt;/sup&gt; May 2019), during (22&lt;sup&gt;nd&lt;/sup&gt; May 2020), and after COVID-19 (28&lt;sup&gt;th&lt;/sup&gt; May 2022) periods were also calculated. Results revealed that the mean SPM values during COVID-19 period (4.56 mg/L) were lower than that before COVID-19 period (8.33 mg/L). Surprisingly, SPM showed an increase of 54% in SPM values after COVID-19 period, compared with during COVID-19 period. The role of human activities including industrial and domestic wastes during the restriction period was the main reason for alteration of pollution loads in the river. Outputs of this study can be used to arrange policies for the sustainable management of aquatic environments and water resources.&lt;/p&gt; &lt;/abstract&gt;

Evaluation of River Water Quality at Bridge Construction Site and Preservation of the Trans Papua Mameh-Bintuni Road West Papua Province

Pembangunan infrastruktur jembatan dan ruas jalan Trans Papua Mameh-Bintuni Provinsi Papua Barat melintasi sungai (Jembatan Mothy I), (Jembatan Mothy-II) dan (Jembatan Yuki-II). Dampak pembangunan tersebut diperkirakan menciptakan penurunan kualitas air sungai dan pencemaran. Kriteria kualitas air sungai ditentukan berdasarkan indeks pencemaran. Sampel kualitas air diambil pada sungai yang terdampak langsung kegiatan pembangunan jembatan dan preservasi jalan Trans Papua Mameh-Bintuni. Parameter kualitas air dan pengambilan sampel air sungai mengacu pada SNI 6989.57:2008. Pengambilan sampel air dilakukan setelah kegiatan pembangunan selesai dilaksanakan. Hasil penelitian menunjukkan bahwa kualitas air pada tiga sungai memenuhi baku mutu air sungai kelas II sesuai Peraturan Pemerintah Nomor 22 Tahun 2021. Indeks Pencemaran sungai (Jembatan Mothy-I), (Jembatan Mothy II), dan (Jembatan Yuki II) masing-masing memiliki nilai Indeks Pencemaran sebesar 0.765; 0.816; dan 0.766. Nilai ini mendeskripsikan bahwa status mutu air pada tiga sungai dalam kategori baik atau memenuhi baku mutu lingkungan untuk kualitas air sungai Kelas II. Indikator biologi, kimia dan fisika berada pada nilai konsentrasi alami, dengan demikian aktivitas pembangunan jembatan dan preservasi jalan Mameh-Bintuni Provinsi Papua Barat yang telah dilaksanakan tidak memberikan dampak negatif terhadap perubahan kualitas air sungai.

Evaluation of River Water Quality Based on Biotic Index of Benthic Macroinvertebrate as Bioindicator (Case study in Genjong River Wlingi Blitar East Java, Indonesia)

This research aims to determine the water quality profile of Genjong River based on physicochemical parameters of water and benthic macroinvertebrates as bioindicators. Sampling was carried out at four different location based on difference of human activity in surrounding. The sampling was done in triple repetition for each station. The activity of station 1 is ecotourism (as reference site or positive control in this study), Station 2 (livestock I), Station 3 (livestock II), and Station 4 (plantation). The water physicochemical parameters were measured including water and air temperature, water current velocity and discharge, conductivity, pH, DO, BOD, TSS, nitrate, and orthophosphate. The result from the identification and calculation of the benthic macroinvertebrates density was used to determine some diversity indices and biotic indices. The difference in the value of each water quality parameter was tested by One-way ANOVA. Based on the abiotic water quality profile, Genjong River water is included as the Class IV category based on Indonesia Government Regulation No. 22 of 2021 with a BOD value of 3.61 – 7.22 mg.L-1. Human activities along the Genjong River have a great impact on decreasing water quality as indicated by increasing of nitrate levels from 0.52 ± 0.07 mg.L-1 at Station 1 up to 0.85 ± 0.07 mg.L-1 at Station 4. Also, orthophosphate levels from 0.02 ± 0.01 mg.L-1 at Station 1 to 0.18 ± 0.02 mg.L-1 at Station 4. Meanwhile, based on benthic macroinvertebrates as bioindicators, Genjong River was classified as lightly (S1, H = 1.74) to moderately polluted (S4, H = 1.24) with toxic materials and slightly contaminated with organic matter (S4 with FBI value = 5.38). The decline in water quality was also shown by the decreasing ASPT value from 4.20 at Station 1 to 3.68 at Station 4.

Evaluation of river water quality by using hierarchical clustering analysis

Assessment of water pollution is a critical study because it can affect humans directly. Likewise, river water is widely used for various daily needs. It is important to group rivers according to their classes so that further analysis and action can be carried out. This article discusses the clustering of rivers in several areas in the southeast part of Central Java Province consisting of 14 sampling stations based on several water quality parameters. The pollutant parameters include TSS, electrical conductivity, pH, BOD, COD, and DO. The method used is Hierarchical clustering in which the object grouping begins with grouping two objects with the closest distance being combined into one cluster, and then continues until one cluster is formed consisting of all objects. The results show that five clusters are the ideal choice. Except for electrical conductivity, the parameters observed are dominantly the difference between clusters. Through the formation of river clusters based on their water quality, the characteristics of each cluster and cluster members with high similarity can be identified.

A data-driven framework for spatiotemporal characteristics, complexity dynamics, and environmental risk evaluation of river water quality

To evaluate the evolution of river water quality in a changing environment, measuring the objective water quality is critical for understanding the rules of river water pollution. Based on the sample entropy theory and a nonlinear statistical method, this study aims to identify the spatiotemporal dynamics of water quality and its complexity in the Yangtze River basin using time series data, to separate the contributions of human activity and climate change to water quality, and to establish a data-driven risk assessment framework for the spatial (potential risk) and temporal (direct risk) aspects of water pollution. The results demonstrate that the spatiotemporal dynamics of water quality and sample entropy in each monitoring section are closely related to the characteristics of the corresponding location. The water quality of the main stream is superior, and its complexity is less than that of the tributaries. Cascade reservoir operation and vegetation status, agricultural production, and rainfall patterns exert great influences in the upper, middle, and lower reaches, respectively. Dam construction, urban agglomeration development, and interactions between river and lake are also influencing factors. An attributional analysis found that climate change and human activities negatively contributed to the evolution of NH3-N concentration in most of the monitored sections, and the average relative contribution rates of human activities to changes in water quality in the main and tributary streams were −55.46% and −48.49%, respectively. In addition, the construction of data-driven risk assessment framework can efficiently and accurately assess the potential and direct water pollution risks of rivers.

Comparative evaluation of river water quality and ecological changes at upstream and downstream sites of dams/sluices in different regulation scenarios

The construction of dams and sluices (DSs) is conducive to human development, but affects river water quality (WQ) and water ecology (WE) seriously. While many studies have explored the DS-induced impact on hydrology, water quality and water ecology, the difference in DS regulations for different objectives and interests (such as flood control, power generation and ecological protection) are not taken into the account although their impacts on WQ and WE are different. Discharge is the key factor to measure different DS regulation and its variation directly affects the long-term WQ and WE in rivers. Thus, studying short-term multi-scenario DS regulation with different discharge is very important for providing insights to their long-term irregular management. Furthermore, the relationships between discharges and the change of WQ indicators are different in the upstream and downstream of DSs and at different distance to DSs in the downstream. However, it is not well understood how the WQ and WE indicators at upstream and downstream sites of DSs change under different regulation scenarios in long-term and short-term. Using the monitored WQ and WE indicators at twelve sampling sites (SPs) of six DSs in the Huai River Basin (HRB), this study investigates the impact of long-term irregular DS regulation on changes in WQ and WE indicators, i.e., the long-term regulation experiment (LTRE), and then the relationship between the alteration of DS discharge flow and changes in WQ indicators, i.e., the short-term regulation experiment (STRE) under four scenarios with different flow magnitudes at one of sluices (Huaidian Sluice). The results of long-term regulations show that the WQ at downstream sites of most DSs was worse than their corresponding upstream sites. The similarity of WE indicators at upstream and downstream sites of DSs was low, meaning the great impact of DS long-term regulation on WE. The results of short-term regulations show that small flow magnitude (20 m3/s in this study) helps release and reduce upstream pollution of DSs as it does not disturb downstream riverbed pollutions, resulting in an increase of downstream river pollution. Further increasing flow magnitude (40 m3/s in this study) helps reduce and release upstream pollution, but increases river pollution significantly at downstream due to the release of pollutions in the sediments of downstream riverbed, which may cause a great river ecological impact since pollutants cannot be diluted and degraded in time. A flow magnitude about 60 m3/s can help release and rapidly dilute and degrade sediment pollutions in downstream riverbed. However, a larger flow magnitude may also be inappropriate due to the strong downstream riverbed erosion except for special regulation requirements. This study can provide more insights for water resources management to develop long-term ecological DS regulation schemes for in HRB and other similar DS dominated basins.

Application of Interval Information Comprehensive Ranking Model Based on Entropy Weight in River Water Quality Evaluation

Wang, Y.; Wu, Y., and Jiang, L., 2020. Application of interval information comprehensive ranking model based on entropy weight in river water quality evaluation. In: Hu, C. and Cai, M. (eds.), Geo-informatics and Oceanography. Journal of Coastal Research, Special Issue No. 105, pp. 137–140. Coconut Creek (Florida), ISSN 0749-0208.In this article, an interval information comprehensive ranking model based on entropy weight is established and applied to river water quality evaluation. In this model, the monitoring interval value of water quality index of river section is weighted with the interval data of standard grade. The weight of each index is calculated by using information entropy technology, and the water quality grade of each section is determined by comprehensive weighted ranking of each section and evaluation grade. The results show that the concept of the model is clear, the calculation is simple, and the evaluation results are objective and reasonable.

Chemical Characteristics of the Karmanasha River Water and Its Appropriateness for Irrigational Usage

Water is a prime natural resource and precious national asset and one of the chief constituents of the environment. The chemical characteristics play a key role in terms of ecological and economic perspectives in the river water. The characterization and evaluation of river water quality in the Karmanasha River is necessary due to its immense importance in the livelihood of the people in the core urban areas of Kathmandu valley, Nepal. In this study, the surface water samples were collected from 16 sites with a 0.5 km interval to characterize and evaluate the water quality mainly from the perspective of its irrigational usage. The assessment was carried out by applying electrical conductivity (EC), sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI), Kelly’s ratio (KR), magnesium adsorption ratio (MAR), cation ratio of soil structural stability (CROSS), Wilcox diagram and water quality index (WQI) including the general hydrochemistry. The general hydrochemistry of river water indicates slightly alkaline in nature with mean pH value 8.07, and the dominance order of major ions follows the pattern of Ca2+&gt;Mg2+&gt;Na+&gt;K+ for cations, and HCO3-&gt;Cl-&gt;NO3- for anions. Furthermore, the results revealed that the water is safe for irrigation purposes based on EC, Na%, SAR, KR, MAR, CROSS, and Wilcox diagram. The results also specified that no severe degradation in water, however, the low DO, and high BOD and COD values than that of the standard value prescribed by Nepal Drinking Water Quality Standard, signify the anthropogenic signature in the river water. This study provides the baseline information about the WQI and suitability of irrigation water quality, and further in-depth studies are required at spatiotemporal levels to get in-depth insights about the ecological health of the river.

Physicochemical characterization and evaluation of river water quality for its potability, Champhai District, Mizoram, NE India

Physicochemical characterization and evaluation of river water quality for its potability, Champhai District, Mizoram, NE India

Study on The Characteristics of Temporal and Spatial Changes of Regional Water Resources

In order to accurately reflect the basic characteristics of the water quality of the different reaches of the Weihe River (Shaanxi section), this paper selects ammonia nitrogen, CODcr, total phosphorus, and total nitrogen, which are more serious and concerned about exceeding the standard in the surface water of the Yellow River basin based on a large number of survey data, draw the curve of four water pollution indicators along the Weihe River (Shaanxi section) in different water periods, and grasp spatially the environmental changes of different parts of the Weihe River (Shaanxi section), different upstream and downstream parts. And the contrast of quality changes, so that the river water quality evaluation is typical and representative, provide a basis for the comprehensive management of the Weihe River basin, and promote the sustainable development of the Guanzhong region.

Evaluation of River Water Quality and Indices for Fish Farm Development (Case study: Kabkian River)

Background: Fish farming requires proper water quality to increase productivity and reduce health risk exposures while they are emission sources in rivers themselves. The purpose of this research is to evaluate river water quality regarding physicochemical parameters coupling with water quality index (WQI) to study the viability of fish farming expansion. Methods: This study is carried out both as field survey and laboratory analysis. Samples were taken bimonthly in 6 periods (2016-2017) from 21 stations from Kabkian River, Iran, including the water body and discharge points. Afterwards, results were statistically analyzed by T-Test regarding the spatial and temporal specifications with SPSS. Results: Experimental results show that dissolved oxygen is over 7 mg/L and WQI is 70 which is classified as good. However, temporal variations of BOD, COD and nitrite concentrations are significant and their average are rather high about 10, 16 and 0.14 mg/L, respectively. Since, BOD is the only parameter with significant spatial variations, it is introduced as the main parameter for river water quality monitoring. Conclusion: Overally, Kabkian water quality is suitable for fish farming. However, due to the possibility of presence of malachite green, it is highly recommended that strict monitoring should be implemented upstream to control fish farm discharges and reduce health risk exposures.n n

Spatial Variation Assessment of River Water Quality Using Environmetric Techniques

The Malacca River provides water resources, recreational activities, and habitat for aquatic animals, as well as serving as a tourist attraction. Nevertheless, the Malacca has experienced water quality changes as a result of urbanization and population growth. Environmetric techniques incorporating hierarchical cluster analysis (HCA), discriminant analysis (DA), and principal component analysis (PCA) have been applied to understand the spatial variation of water quality in nine sampling locations within the river basin. HCA has grouped the nine sampling locations into two clusters based on physico-chemical and biological water quality data and trace elements in water. DA analysis indicated that temperature, salinity, coliform, EC, DO, BOD, COD, As, Hg, Cd, Cr, and Zn are the most significant parameters that reflect the overall river water quality for discrimination in clusters 1 and 2. PCA resulted in six components in cluster 1 and eight components in cluster 2. Agricultural activities and residential areas are the main sources of pollution within cluster 1, while a sewage treatment plant and industrial activities are the main sources of pollution in cluster 2. This study has provided useful information for identifying and investigating the pollutant sources through the water quality variations in the river. However, continuous evaluation of river water quality will help in greater understanding of river water quality for a more holistic management of the river basin.

Hydrochemical evaluation of river water quality\u2014a case study

Rivers are one of the most environmentally vulnerable sources for contamination. Since the rivers pass through the cities, industrial and agricultural centers, these have been considered as place to dispose the sewages. This issue is more important when the river is one of the main sources of water supplying for drinking, agricultural and industrial utilizations. The goal of the present study was assessing the physicochemical characteristics of the Tireh River water. The Tireh River is the main river in the Karkheh catchment in the Iran. To this end, 14 sampling stations for measuring the physicochemical properties of Tireh River along the two main cities (Borujerd and Dorud) were measured. The results showed that (except SO4) Mg, Ca and other anions and cations have concentrations under WHO standard limitation. Almost all samples have suitable conditions for drinking with regard to the WHO standard and in comparison with agricultural standard (FAO Standard), and the potential of water is suitable for irrigation purposes. According to Wilcox diagram, 78 % of samples were at the C3-S1 and 21.5 % were at C2-S1 classes. The piper diagram shows that most of samples are bicarbonate and calcic facies.

Water resources planning for a river basin with recurrent wildfires

Situated in the north of Portugal, the Beça River basin is subject to recurrent wildfires, which produce serious consequences on soil erosion and nutrient exports, namely by deteriorating the water quality in the basin. In the present study, the ECO Lab tool embedded in the Mike Hydro Basin software was used for the evaluation of river water quality, in particular the dissolved concentration of phosphorus in the period 1990–2013. The phosphorus concentrations are influenced by the burned area and the river flow discharge, but the hydrologic conditions prevail: in a wet year (2000, 16.3km2 of burned area) with an average flow of 16.4m3·s−1 the maximum phosphorus concentration was as low as 0.02mg·L−1, while in a dry year (2005, 24.4km2 of burned area) with an average flow of 2m3·s−1 the maximum concentration was as high as 0.57mg·L−1. Phosphorus concentrations in the water bodies exceeded the bounds of good ecological status in 2005 and between 2009 and 2012, water for human consumption in 2009 and water for multiple uses in 2010. The River Covas, a right margin tributary of Beça River, is the most appropriate stream as regards the use of water for human consumption, because it presents the biggest water potential with the best water quality. Since wildfires in the basin result essentially from natural causes and climate change forecasts indicate an increase in their frequency and intensity in the near future, forestry measures are proposed to include as a priority the conversion of stands of maritime pine in mixed stands of conifer and hardwood species.

A Solution for a Water Quality Model in a Uniform Stream Channel using New Iterative Method

During the last decade, political awareness of river water quality issues has increased significantly. New environmental policies have a requirement for improved methods for the investigation and evaluation of river water quality. Moreover, the derivation and assessment of management practices is also necessary. An efficient Perturbation Iteration Algorithm for solving the water quality assessment model has been developed. The employed equation of this uniform flow model is one-dimensional Advection-DispersionReaction equation that has variable coefficients. This water quality model requires the calculation of the substance dispersion considering the water velocity in the channel. Numerical values are obtained by using the Runge-Kutta-Fehlberg fourth-fifth order method for comparison. It was discovered that Perturbation Iteration Algorithm solution gels well with the numerical solution. Two examples are included to demonstrate the efficiency, accuracy, and simplicity of the proposed method.

Evaluation of River Water Quality in Agricultural Watershed with the Environmental Standards

Japan has general environmental standards for organic matter in its public water bodies. However, there are no environmental standards for nutrient salts such as phosphorus (P) and nitrogen (N) in river water. In this study, the water quality of rivers at normal water level was evaluated in agricultural watersheds by focusing on water quality standards. The investigated sites are in the Tokachi area (24 watersheds; upland and dairy farming) and the Nemuro area (11 watersheds; large-scale dairy farming), which are in Eastern Hokkaido. The investigations were carried out in the two agricultural areas in 2005, 2006 and 2012. Electrical conductivity (EC) and water temperature were measured at the same time as river water samples were collected in the two areas. Water quality was analyzed for potential of hydrogen (pH), biochemical oxygen demand (BOD), suspended solids (SS), total phosphorus (T-P), total nitrogen (T-N) and other values. Most of the values associated with organic matter, such as pH, BOD and SS, in river water were within the thresholds for the standards of The Environmental Standards Concerning the Conservation of the Living Environment (Rivers). In contrast, some values of nutrient salts (N and P) exceeded the thresholds (T-P≦0.1 mg/L, T-N≦1.0 mg/L). Many of the watersheds in the Tokachi area had T-N concentration in excess of 1.0 mg/L. This suggests that the concentrations of nutrient salts (P and N) increase with increases in agricultural land development in a watershed. For the evaluation of river water quality in agricultural watersheds, it was found to be necessary to measure both organic matter and nutrient salts as indices of water quality. And it was found that controlling the runoff of P and N from agricultural land is essential for water quality conservation in public water bodies.