Nonpoint source pollution from agriculture is the leading cause of nutrient pollution in the US. This paper addresses whether localized, farmer-led programs can cost-effectively reduce nonpoint source pollution by increasing the adoption of agricultural conservation practices. We study this in the context of an innovative program in Wisconsin that incentivizes farmers to take collective leadership of improving water quality in their local watersheds. Using a shift-share instrumental variables design, we find that a 10 percentage point increase in farmer participation in these programs leads to a 0.03 mg/L reduction (14%) in ambient phosphorus concentrations in local streams and rivers. We also show that this change causes an increase in the adoption of cover crops, conservation tillage, and more diverse crop rotations. Importantly, this localized approach achieves water quality and conservation improvements at a substantially lower cost than existing federal subsidy programs, demonstrating the potential for bottom-up approaches to address nonpoint source pollution in other contexts.

Nitrate contamination of drinking water is a widespread concern and threatens human health. The magnitude of the health consequences depends on individuals’ ability to avoid exposure. This paper uses an event-study framework to uncover avoidance behavior and infant mortality outcomes following public notifications required by the Safe Drinking Water Act. Using store-level scanner data, I estimate that consumers spend $4.5 million annually on bottled water to avoid nitrate-contaminated drinking water. This protective behavior leads to 20 avoided infant deaths per year or $223 million in monetized benefits. These results underscore the benefits and role of environmental information policy in inducing avoidance of environmental hazards.

Adaptation to environmental change can exacerbate existing externalities in common-pool natural resources. We document one such case: Farmers in California respond to heat and drought by extracting more groundwater, lowering the water table, and harming access to drinking water for nearby residents. Using yearly variation we show that surface water scarcity and heat increase agricultural well construction, groundwater depletion, and domestic well failures, and that well construction accounts for a large share of the latter effects. In our setting, adaptation also exacerbates inequality: Effects on domestic well failures are concentrated in low-income and Latino communities.

Nitrate pollution threatens human health and ecosystems in many regions of the world. Although scientists agree that nitrogen compounds from human activity, notably agriculture, enter the groundwater system, empirical estimates of the impacts of land use on nitrate concentrations in well water are still lacking. We provide evidence of such impacts by combining nitrate concentration measurements from about 6,000 groundwater wells with a data set of remotely sensed land uses for California over the period 2007–2023. Results show that a 10 percentage point increase in the share of land used to grow high-nitrogen crops within 500 meters of a well relative to undeveloped land is associated with a 12% increase in nitrate concentrations, while a 10 percentage point increase in the share of land used for low-intensity urban development is associated with a 10% increase. Local dairy cattle populations also meaningfully contribute to nitrate pollution. However, conditioning on initial nitrate measurements, we find limited evidence that human activity affects nitrate concentrations a decade later.