Vexing water quality challenges remain, particularly those due to the management of land. This issue of Choices reflects on innovative approaches to addressing "nonpoint sources" of pollution.

While successful at addressing point source pollution, the U.S. Clean Water Act is limited in addressing nonpoint source pollution sources such as agricultural runoff and stormwater. To address this, tools ranging from regulatory total maximum daily loads (TMDLs) to voluntary water quality trading are being implemented, with mixed results to date.

States have historically relied on voluntary adoption of conservation practices to address poor water quality in agricultural watersheds. However, some states have adopted regulations to address these problems. Examples of these regulations are provided, including a novel set of regulations adopted by Florida in the Everglades Agricultural Area.

The ineffectiveness of agricultural policies for reducing water quality impairments has prompted governments and others to experiment with new approaches. We examine innovations that make use of economic tools to engage the agricultural sector in nutrient and sediment control, including some types of water quality trading and novel incentives.

The integration of biophysical science and socioeconomic analysis is crucial to good program design. The scope of U.S. conservation has increased, and there may be trade-offs between some policy goals. Integrated modeling quantifies such trade-offs, and helps assess the activities, payments schemes, and benefits that policies can achieve.

Low-impact development (LID) is used in many urban areas to reduce urban water pollution. LID can cost less than conventional approaches while generating additional benefits. Optimal policy design should consider all of the benefits and costs from LID, administrative challenges, financing, and how citizens are involved in achieving program success.

Many state and local governments are initiating new policies to change behavior and address polluted runoff impacts to coastal and estuarine areas. This paper surveys success and challenges of pollutant trading programs, rebate retrofits, land acquisition programs, and source control measures.

In the EU nutrient pollution from agriculture is addressed through farm income support policies coupled with environmental cross-compliance, environmental regulations, and agri-environmental payments. Despite implementation of multiple policy instruments agriculture has remained a major source of both nitrogen and phosphorus pollution. Hence, there is a need for more spatially targeted and tailored policies, such as conservation auctions and performance-based payments.