[Objective] This study aims to determine the eutrophication status of Shahu Lake

Ningxia Hui Autonomous Region

and to calculate the environmental capacity of the lake for major pollution as a means of providing a basis for reducing the pollution load and improving the environmental protection of Shahu Lake.[Methods] Water samples were collected in January

April

July

and October during 2015-2017 to measure physical and chemical parameters. A comprehensive eutrophic state index was applied to assess the trophic status

and the Vollenweider and Dillon model was used to analyze the environmental capacity of permanganate index(CODMn)

total nitrogen (TN)

and total phosphorus (TP) of the lake under four different water quality target scenarios.[Results] During 2015-2017

Shahu Lake was mildly eutrophic in spring and winter

and moderately eutrophic in summer and autumn. In scenarios two and three of the water quality targets

the remaining environmental capacities for CODMn

TN and TP were zero. In scenario four

the remaining environmental capacity of the lake for TN was zero

whereas that for CODMn still had a remaining capacity. The environmental capacity of TN had a surplus in 2015

but this was reduced to zero in 2016-2017. On the basis of the water quality in 2017

to attain class Ⅲ water quality requirements

CODMn

TN

and TP should be reduced to 655.97

39.27

and 1.41 tonnes

respectively

which correspond to reduction rates of 112.89%

45.58%

and 37.60%

respectively. In order to attain class Ⅳ water quality requirements

the CODMn

TN and TP should be reduced by 0.0

15.83

and 0.94 tonnes

respectively

which correspond to reduction rates of 0%

18.37%

and 25.07%

respectively.[Conclusion] Shahu Lake has certain degree of pollution and has reached a state of eutrophication

the environmental capacities of CODMn

TN

and TP in the lake are greater than the target requirement

and should be managed and protected.