it is early winter. on the vast erhai lake, sparkling water is rippling. in the distance, the cang mountain rolls in lush green. how does today’s erhai lake look like? 
  wastewater interception around the erhai lake
the erhai lake is the seventh largest freshwater lake in china. in recent years, due to population increase, accelerated urbanization, and the rapid growth of the tourism industry, the environment of the erhai lake has been seriously affected, and controlling wastewater, garbage and agricultural pollutants has become an increasingly tough task. chen hao, secretary of the cpc yunnan provincial committee, pointed out that the erhai lake is in urgent need of protection, and it is necessary to take drastic measures. 
  high-altitude lakes or plateau lakes, featuring a small catchment area, high evaporation rate, poor storage capacity, and very slow water replacement, have a relatively fragile ecosystem. one of the biggest problems facing the erhai lake is wastewater produced by rural areas and surrounding restaurants and hotels. 
  to completely intercept wastewater flowing into the erhai lake, the dali bai autonomous prefecture started interception around the lake. 
  in october 2015, the first phase of the dali erhai lake water environment management project announced its commencement. up to now, a total of 90.63 km of interception trunk channels and 13 wwtps have been built, forming a “large artery” for interception around the lake. 
  on this basis, the second phase and other relevant projects have started, to create “capillary vessels” and “cell units” for the interception system of the erhai lake. across the 469 villages in the erhai lake watershed, 90,300 family septic tanks, 2,130 km of wastewater collection sewers, 82 new and relocated wastewater treatment facilities, 45 multi-level ecological pond systems, and 47 tailwater wetlands have been built or created. 
  “now every village has sewers, so that domestic wastewater is not directly discharged into the erhai lake,” said a villager from meiba village, xizhou town, dali city. 
  in april 2017, the cpc dali municipal committee and dali municipal people’s government investigated restaurants and hotels in core areas, shutting down 2,498 restaurants and hotels in the erhai river watershed, which was called the “most severe erhai river protection order ever”. 
  “if we do not shut down these restaurants and hotels before the interception trunk channels are built, wastewater will still be discharged directly into the erhai lake, which is extremely unfavorable for the protection of the erhai lake. we shut them down first and then act quickly to build wastewater treatment facilities, making sure that wastewater is collected by sewers,” said yang jian, governor of dali prefecture, “after more than a year of rectification, many compliant restaurants and hotels have reopened.” 
  the yang brook is one of the famous “cang mountain eighteen brooks”. the clear stream flows from the foot of the cang mountain into the erhai lake. on the banks of the stream, workers are leveling land, planting trees and building revetments. according to the head of the project, dali prefecture is carrying out a comprehensive management of 34 rivers flowing into the erhai lake. all wells in the urban built-up areas and all irrigation intakes along the “cang mountain eighteen brooks” have been sealed, and tap water has been delivered to rural areas. as a result of strict management, the water circulation of the “cang mountain eighteen brooks” has restored, and the amount of clean water entering the lake has increased significantly. 
   underground wwtps: a friendly solution to residents and the environment 
     how is the intercepted wastewater treated? will the wwtps built near the erhai lake affect local tourism? 
  “six wwtps have been built underground near the erhai lake,” cweg chairman hou feng said, “this is a friend solution to residents and the environment.” 
  at dali town wwtp, the reporter saw that all the treatment facilities are built underground below beautiful lawns and the air was fresh. hou feng said, “our underground wwtp system treats wastewater using ecological technology. treated water can be used to recharge the river, or for fire protection, greenbelt irrigation, and farmland irrigation.” 
  included in the second batch of ministry of finance demonstration ppp projects, the six wwtps have a total budget of rmb 3.49 billion, exceeding the total investment in the protection and management of the erhai lake during the “12th five-year plan” period. “in this project, the government used rmb 100 million to incite rmb 2.88 billion of private funds. completed wwtps will be professionally operated by cweg, who provides public lake management service on behalf of the government,” said yang jian, “so far, five erhai lake protection and management ppp projects in dali prefecture have been included in the ministry of finance demonstration projects, and have all been signed.” 
  in june this year, a huge wastewater interception and control system integrating wwtps, wastewater treatment stations, sewers, pipe networks and ponds will be put into operation, covering each township and each family across the erhai lake watershed.  
  despite the present achievements, there is still a long way to go in the management of the erhai lake.
according to reports, achievements have been made in the management of the erhai lake at present. from january to may 2018, the water quality reached surface water quality standard class ii, and from june to october, it reached class iii. particularly, the nearshore water quality and water environment have significantly improved compared to previous years. according to the china surface water environment quality report released by the ministry of ecology and environment, the water quality of the erhai lake is “good” and “mesotrophic”. 
  despite the present achievements, there is still a long way to go in the management of the erhai lake. more strict measures will be taken for a better erhai lake. 
  to consolidate the achievements, dali prefecture comprehensively upgraded erhai lake’s ecological and environmental monitoring network. specifically, it created onsite and satellite remote algae bloom warning and monitoring systems, installed monitoring devices at 330 key monitoring sites of major rivers flowing into the erhai lake, and built 14 inspection teams for the inspection of 84 routine monitoring sites. these measures ensure the comprehensive monitoring of both surface water and cross section water.  
  at present, dali is drawing “three lines” to delineate lake, nearshore and core water environmental protection areas. this measure will play an important role in restoring the natural ecological coastline of the erhai lake, forming a complete transitional zone, improving the stability of the lake’s ecosystem, preventing ecological degradation, and improving water quality. 
  although the protection and management of the erhai lake has been progressing orderly and productively, it is a fact that the erhai lake’s ecosystem is still relatively fragile. interception has significantly decreased the phosphorus concentration, but the nitrogen concentration is still high due to heavy agricultural non-point source pollution. to create a clean and clear erhai lake, there is still a long way to go, and heavy investment in the early stage is still a bottleneck. the protection and management of the erhai lake is still very urgent and arduous, requiring further investment and efforts. 
produced by cms 网站群内容管理系统 publishdate:2021/11/05 09:49:22