Soil erosion is a major source of pollution in the United States. Erosion can cause both on-site and off-site damages. It has been argued that off-site damages are a significant component of soil conservation benefits and are currently not well known. Off-site effects of soil erosion are uncompensated externalities. Given significant external costs from erosion, there may be potential for net gains in social welfare from increased soil conservation. The major objective of this study was to examine, and where possible estimate, the off-site costs of soil erosion in the Willamette Valley. The value of erosion was measured in terms of increased production costs. These costs are incurred by economic agents in offsetting the effects of erosion. Six types of publicly owned enterprises were studied to determine erosion damages and related costs. These were municipal water supply, county and state road agencies, navigation supply, water storage reservoirs, and hydroelectric power plants. Of these enterprises, only water storage reservoirs and hydroelectric power plants did not incur substantial costs to offset the effects of erosion. Municipal water treatment costs were found to be significantly affected by erosion. A sediment damage function for the water treatment process was estimated using econometric modeling. The estimated coefficients relating suspended sediment and treatment costs indicated that the latter increased with an increase in river borne sediment. A 50 percent reduction in river turbidity experienced by the treatment plant studied would decrease chemical water treatment costs and sediment disposal costs by $4750 per year or approximately $4.55 per million gallons of water treated. A 50 percent reduction in sediment loads for the entire Willamette Valley would reduce municipal water treatment chemical costs by an estimated $231,000. An average cost analysis was also performed. This analysis indicated water treatment costs were $21.00 per million gallons of water treated. Inference to total municipal surface water supply in the Willamette Valley yielded an annual average erosion cost estimate, from natural and man made sources, of $1,052,000. County and state road maintenance departments must frequently clean drainage structures in response to sediment deposition from erosion. Benton county road maintenance costs, for sediment removal, were estimated to be approximately $222,000 per year in 1984 dollars. An inference to all county road departments in the Willamette Valley, yielded a total erosion cost estimate of $3,743,000 per year. State highway maintenance costs in the Valley due to sediment front erosion were estimated to be $503,000 per year in current dollars. Sediment removal involved with maintenance of a navigation channel on the lower reach of the Willamette river costs an average of $270,000 per year, expressed in 1984 dollars. Aggregate erosion costs for all these activities were estimated to be $4,758,000 per year in current dollars. This figure is equal to approximately $0.67 per acre and $432 per square mile for the Willamette Valley. These findings suggest that there exists potential for off-site benefits from increasing soil conservation activities in the Valley. However the economic feasibility of soil conservation projects in the Willamette Valley depends on their implementation costs as well as the on-site and off-site benefits. Cost studies of other activities impacted by erosion are needed to estimate the total off-site costs of erosion in the Willamette Valley.

Despite almost a century of research and extension efforts, soil erosion by water, wind and tillage continues to be the greatest threat to soil health and soil ecosystem services in many regions of the world. Our understanding of the physical processes of erosion and the controls on those processes has been firmly established. Nevertheless, some elements remain controversial. It is often these controversial questions that hamper efforts to implement sound erosion control measures in many areas of the world. This book, released in the framework of the Global Symposium on Soil Erosion (15-17 May 2019) reviews the state-of-the-art information related to all topics related to soil erosion.

This volume deals with land degradation, which is occurring in almost all terrestrial biomes and agro-ecologies, in both low and high income countries and is stretching to about 30% of the total global land area. About three billion people reside in these degraded lands. However, the impact of land degradation is especially severe on livelihoods of the poor who heavily depend on natural resources. The annual global cost of land degradation due to land use and cover change (LUCC) and lower cropland and rangeland productivity is estimated to be about 300 billion USD. Sub-Saharan Africa (SSA) accounts for the largest share (22%) of the total global cost of land degradation. Only about 38% of the cost of land degradation due to LUCC - which accounts for 78% of the US$300 billion loss – is borne by land users and the remaining share (62%) is borne by consumers of ecosystem services off the farm. The results in this volume indicate that reversing land degradation trends makes both economic sense, and has multiple social and environmental benefits. On average, one US dollar investment into restoration of degraded land returns five US dollars. The findings of the country case studies call for increased investments into the rehabilitation and restoration of degraded lands, including through such institutional and policy measures as strengthening community participation for sustainable land management, enhancing government effectiveness and rule of law, improving access to markets and rural services, and securing land tenure. The assessment in this volume has been conducted at a time when there is an elevated interest in private land investments and when global efforts to achieve sustainable development objectives have intensified. In this regard, the results of this volume can contribute significantly to the ongoing policy debate and efforts to design strategies for achieving sustainable development goals and related efforts to address land degradation and halt biodiversity loss.