Author:Li Xing

Watershed management is determined by the natural characteristics of water resources，It is an important part of the water management system，It is a water resources management model generally respected by countries around the world.。2016 The "13th Five-Year Plan" Key River Basins Comprehensive Management Plan for Water Environment" issued by the National Development and Reform Commission in 2016 included the "Water Pollution Prevention and Control Action Plan"("Ten Waters") The work is implemented in the river basin、area。

2017 year 3 month 14 to 16 day，INTERNATIONAL FUND FOR CHINA'S ENVIRONMENT(International Fund for China’s Environment) Organized a delegation from the Yunnan Provincial Department of Environmental Protection to visit watershed management agencies in the United States and Canada，Develop international exchanges on watershed management。Lan Jun, deputy director of the Yunnan Provincial Department of Environmental Protection、Chen Li, Director of the Policy and Regulations Division of the Yunnan Provincial Department of Environmental Protection、Guan Qiong, Director of the Lakes Division of the Yunnan Provincial Department of Environmental Protection、Guan Minghong, director of the Environmental Protection Bureau of Lijiang City, Yunnan Province, and Li Xing, project manager of the International China Environment Foundation, attended the visit。Respondents included the U.S. Chesapeake Bay Program Office(Chesapeake Bay Program Office)、U.S. Environmental Protection Agency, Division 5, Water Division(EPA Region 5 Water Division)、U.S. Environmental Protection Agency Great Lakes National Program Office(EPA Great Lakes National Program Office) and the WWF-Canada Freshwater Conservation Program(WWF-Canada Freshwater Program)。

The topics of this exchange include:Cross-administrative watershed management model、Pollutant discharge permit system、Non-point source pollution management and control methods、Factors controlling water eutrophication pollution、Coordination and balance between regional development and watershed protection。

Lan Jun, deputy director of the Yunnan Provincial Department of Environmental Protection, introduced the overview of plateau lake management in Yunnan Province to representatives from the United States and Canada during the exchange.。The lakes in Yunnan Province belong to the Yunnan-Guizhou Plateau Lake Area，It is one of the five Great Lakes areas in the country.。Lakes in Yunnan Province have three major characteristics: 1、particularity:A group of plateau lakes formed by the evolution of the Yunnan-Guizhou Plateau, It is a unique concentrated distribution group of rift lakes in the world.; 2、Diversity: The difference between deep water lakes and shallow water lakes、Differences between nutritional processes、Differences in water quality background、Differences in material input processes within the watershed、Differences in ecological structure; 3、complexity : Water pollution shows a basin-wide nature、Complexity、structural、long-term characteristics。

Currently，Targeting the “nine major lakes” in Yunnan Province (Dianchi Lake、Erhai Lake、Fuxian Lake、Cheng Hai、lugu lake、Yang Zonghai、Xingyun Lake、Qilu Lake、Yilong Lake) governance，The government adopts a “one lake, one policy” management approach。Take Dianchi Lake as an example，Due to the high population density in cities,The pollution load of Dianchi Lake far exceeds the environmental capacity，Cause eutrophication of water bodies。Regarding the Dianchi Lake issue，The government takes both engineering and management measures、Co-governance of internal and external sources、The governance idea of ​​co-decrease of stock and increment。Specific measures include six major projects: Sewage interception and traffic projects around the lake、Agricultural and rural non-point source control projects、Lake channel management project、Water diversion and water conservation projects in outer basins、Ecological construction project、Ecological dredging project。

Deputy Director Lan Jun emphasized，Although the management work of the nine great lakes in Yunnan Province has achieved initial results,，However, we still face many difficulties and challenges。First，Erhai Lake、Fuxian Lake、Difficulties in spatial constraints for governance of Lugu Lake and Yangzonghai，Prevention and protection measures are difficult to implement，Facing the contradiction between protection and development。second，Pollution load still exceeds environmental carrying capacity，Prominent non-point source pollution，It is difficult to control pollution in the rainy season due to impact loads.。third，Cheng Hai、Qilu Lake、Yilong Lake faces water shortage problem。fourth，Dianchi Lake Caohai、Yilong Lake、Xingyun Lake faces the problem of grass-algae mutual transformation。fifth，For Dianchi Lake、The control factors of algae pollution in Xingyun Lake are still controversial。

3 month 14 day，The delegation first visited the Chesapeake Bay Project Office in the United States(Chesapeake Bay Program Office)，Chesapeake Bay is an estuary from the Atlantic Ocean that extends inland，The drainage area is 64,200 square miles. (166534square kilometers)，There are more than 150 tributaries，The basin covers six states in the United States ( new York、pennsylvania、delaware、maryland、virginia、west virginia) and washington d.c.。Chesapeake Bay was also very polluted in the 1970s，But after more than thirty years of governance，At present, the water body has basically recovered。Chesapeake Bay management is the most successful water environment management case in the United States，There are many successful experiences worth learning from。

Mr. Ning Zhou, expert of the wastewater research working group of the Chesapeake Bay Project, shared with the delegation the two major elements for successful Chesapeake Bay watershed management.：Effective leadership structures and sustained scientific governance。

Chesapeake Bay project approved by Congress，A strong leadership body, the Chesapeake Bay Remediation Executive Committee, was established。The Executive Committee is composed of the Administrator of the U.S. Environmental Protection Agency、The governors of the six states and the directors of the river basin commissions directly serve as。The Executive Committee mainly decides on major policies and measures for rectification work,Sign a joint action agreement,and provide strong leadership and support in practical work。The Executive Committee meets annually,Review project progress,Sum up experience,Determine the direction and policy measures for next steps。

The most representative management tool in the Chesapeake Bay is the maximum daily load(Total Maximum Daily Load,TMDL for short )，This is a comprehensive "total pollution control"，by the Federal Environmental Protection Agency in 2010 year 12 month 29 day enacted,Is the largest TMDL in the United States。Che Sapeake Bay TMDL aims to ensure that 2025 All the pollution control measures needed to fully restore the Bay Area and its tidal rivers。The Chesapeake Bay TMDL identifies contaminants that water bodies can receive and still meet water quality standards (nitrogen、phosphorus、sediment) total amount，Enables states to allocate total pollution to various pollution emission sources，To achieve scientific and effective pollution control。

TMDL controls all sources of pollution,Including point sources and area sources。TMDL is very specific in controlling pollution sources，Point sources can be specific to individual households that are not yet connected to sewage pipes.，Area sources can be specific to the cleaning frequency of urban road surfaces.。The specific water quality standards and total pollution allocation of TMDL need to be calculated through hydrological and hydraulic models，Moreover, model establishment and calibration also rely on a large amount of water quality and hydrological data.。therefore，The workload of developing TMDL is very large，The Chesapeake Bay took nearly 30 It took years to complete the entire Bay Area’s nitrogen、phosphorus、Development of TMDL for sediments。

Based on TMDL，The U.S. federal government requires six state governments to develop their own watershed implementation plans (Watershed Implementation Plan)，This includes the adoption of a pollution discharge permit system( National Pollutant Discharge Elimination System，NPDES for short) to control point source pollution。U.S. Federal Clean Water Act(Clean Water Act) No one is allowed to discharge pollutants into water bodies through “point sources”，Unless they have an NPDES license。The permit will contain limits on what can be emitted、Monitoring and reporting requirements、and other provisions。In addition to general domestic sewage and industrial wastewater being controlled as point sources，NPDES also manages three categories of stormwater discharge sources:：Municipal independent storm sewer system (MS4)、Construction and industrial activities。

3 month 15 day，Delegation goes to Chicago，Visited the Water Division of the U.S. Environmental Protection Agency, Division 5 (EPA Region 5 Water Division) and the U.S. Environmental Protection Agency’s Great Lakes States Program Office(EPA Great Lakes National Program Office)。Water Division major support in the Great Lakes、six jurisdictional states and 35 Tribe-wide water plans and actions。The Great Lakes National Program Office is responsible for coordinating the Great Lakes Water Quality Agreement between the United States and Canada. (Great Lakes Water Quality Agreement) A series of actions taken to restore and protect the integrity of the Great Lakes Basin ecosystem。

Mr. Peter Swenson, Director of the Watershed and Wetlands Division of the Fifth Division of the U.S. Environmental Protection Agency, first introduced the water quality status of the Great Lakes Basin.。The Great Lakes Basin is within the scope of the assessment，52%of rivers and 68% of lakes are still polluted，最主要的问题是水体富营养化和藻类氰基毒素。Then，水司水质标准处专家 Meghan Hemken 女士介绍了美国水质标准的制定。 美国联邦的水质标准由三部分组成: 指定用途、水质基准、反退化机制。联邦没有统一的水质标准限制，具体的标准制定需要因地制宜。在五大湖流域，制定富营养物质的标准中纳入了因果变量(氮和磷)和响应变量(叶绿素 a 和透明度)，每个变量的数值取决于水体的指定用途和当地的生态情况 (包括土地覆盖、地质、规模等)。对于藻类释放的氰基毒素，美国联邦环保局制定了针对不同用途的建议标准，例如建议适于游泳的水体中微囊藻毒素浓度不高于 4ug/l。

代表团与美国专家就水体富营养化污染控制因素以及区域发展与流域保护的协调平衡展开了进一步讨论。

关于水体富营养化污染控制因素，美国专家普遍认为，对于内陆湖，磷是主要引水体起富营养化的污染物，对于靠近出海口的流域，氮是主要的污染物。磷是藻类爆发生长的诱因。氮影响藻类的种类，氮也诱使藻类释放氰基毒素。对于季节性的藻类爆发现象，氮的贡献更大。关于区域发展与流域保护的协调平衡，兰骏副厅长表示中国的水质标准中也有包括了 “水质不得低于现状” 的要求，这点类似于美国标准中的反退化机制。however，有一部分原来没有受到人类影响的地区需要发展，平衡地区发展和水质反退化相当困难。美方专家表示美国政府同样面临发展与保护相平衡的问题，美国对与一些未被开发的水体，将其划定为 “优秀资源水体” (Outstanding resource water body)，禁止周围一 切可能产生污染的人为活动。but，在州政府定义水体的指定用途时，并不是所有未被开发的水体都会被定义成 “优秀资源水体” , 州政府可能会考虑到当地发展的潜力和需要，将这些水体其指定为 “可以游泳” 或 “可以钓鱼” 的用途，样的标准就没那么严格，可以在保持指定用途的基础上适度开发。但需要强调的是， 一旦确定水体的指定用途，将不可更改，必须严格遵循。

美国联邦环境保护局五大湖国家项目办公室专家 Santina Wortman 女士介绍了以伊利湖为例的流域磷负荷减排行动。伊利湖的水体富营养问题是五大湖中最严重的，从上世纪九十年代开始，伊利湖每年夏季都会经历藻类爆发现象，最严重的是 2014 year，藻类毒素导致安大略省、俄亥俄州和托莱岛服务的饮用水处理厂停产，影响了 50 万居民。导致伊利湖的水体富营养化的两大因素是：湖水深度浅 (平均深度 19 Meter) 和农业面源污染 (周围 60-80%的土地用于农业)。

尽管五大湖流域没有 TMDL，在美国与加拿大签署的五大湖水质协议的指导下，五大湖国家项目办公室的专家团队同样坚持着科学的污染负荷总量控制研究。基于长期的点源和面源磷负荷记录，专家团队应用多个模型将磷负荷与富营养化反应关联，计算出推荐的磷负荷目标，以实现所需的湖泊生态系统目标。

关于控制磷污染排放的具体措施，Santina 提出了采用 “多屏障系统管理” 的方法，这种方法不仅需要控制磷在源头的施用，如调节洗涤剂中的磷、限制在冻结或积雪覆盖的地面施用肥料、开发和推广农业最佳管理手段；同时需要防止施用于土地的磷被冲刷进河流，如使用高渗透性的路面材料、建设河岸湿地等。

It is worth noting that，对于农业面源污染，法律并未授权美国联邦政府对农民采取强制控制措施，更多的是依赖排污者的自愿性行为。therefore，联邦环保局采用以引导为主、资金支持为辅的管理方法。美国联邦环境保护局第五分局水司流域处专家 Janette Marsh 女士和地下水及饮用水处专家 William Spaulding 先生分别介绍了自愿性流域规划与管理方法以及从保护饮用水源角度出发的流域管理方法。两位专家均表示，水资源保护的成败取决于与联邦和州政府之间的合作，以及国防、Environmental protection、农业、住房、交通运输、卫生等各政府 部门之间的协调。

3 month 16 day，代表团抵达多伦多，访问加拿大世界自然基金会淡水保护项目(WWF-Canada Freshwater Program)，这是世界自然基金会在全球的第一个淡水保护项目,致力于保护加拿大 25 个主要的流域，并期望在 2025 年实现所有水体生态健康的目标。

淡水保护项目流域报告部专家 Anthony Merante 提出，融雪盐是五大湖的 “新” 污染物。由于加拿大冬季降雪量大，融雪盐被过度使用，道路上的盐含有氯化物 (NaCl、CaCl2、MgCl2)，氯化物可能会干扰许多淡水物种的呼吸调节、离子调节和水合的能力。淡水保护项目正联合安大略省南部的居民和政府参与减盐计划，改变过度使用盐的态度和行为，减少有害氯化物流入五大湖。

淡水保护项目专家 Heather Crochetiere 介绍了项目组如何协助社区居民开展污染控制行动，其中包括了建立社区间的淡水保护网络，促进社区间的信息共享与合作。Other，WWF 还成立了 Loblaw 淡水保护基金，利用社会和企业捐赠的资金，奖励和支持全国范围内优秀的淡水保护行动。

代表团与加拿大专家就跨区域流域管理展开了进一步讨论。Elizabeth 女士表示，尽管加拿大在农业面源污染上相较于美国有更严格的措施，包括更严格的化肥农药使用标准、以及通过限制农田与农产品销售点的距离从而实现更合理的农业用地规划；but，由于加拿大方面对五大湖的污染贡献不足 5%，他们的努力对于五大湖的水质改善并不明显。兰骏副厅长表示，在跨区域流域管理中，细分各个排污者对流域的污染贡献和责任非常关键。

此次访问，促进了中国与美国和加拿大之间在流域管理方面的交流，尽管目前中国与美加两国的经济发展和环境保护处于不同的发展阶段，不能进行简单的对比，对他们的具体做法也不能盲目地照搬，但是美加两国在流域管理体制建设、科学研究以及公民参与等多方面的很多经验和做法仍值得我们学习和借鉴。

参考文献:
《完善水治理体制研究》课题组. 《国外流域管理在水治理体制中的地位和作用》

吴舜泽、徐敏、马乐宽等.《重点流域“十三五”规划落实“水十条”的思路与重点》