billion for asset retirement obligations at year-end 2016 related primarily to upstream properties.

For the company’s other ongoing operating assets, such as refineries and chemicals facilities, no provisions are made for exit or cleanup costs that may be required when such assets reach the end of their useful lives unless a decision to sell or otherwise abandon the facility has been made, as the indeterminate settlement dates for the asset retirements prevent estimation of the fair value of the asset retirement obligation.

Refer to the discussion below for additional information on environmental matters and their impact on Chevron, and on the company's 2016 environmental expenditures. Refer to Note 25 on page FS-61 for additional discussion of environmental remediation provisions and year-end reserves. Refer also to Note 26 on page FS-62 for additional discussion of the company's asset retirement obligations.

Suspended Wells Information related to suspended wells is included in Note 22, Accounting for Suspended Exploratory Wells, beginning on page FS-54.

Income Taxes Information related to income tax contingencies is included on pages FS-49 through FS-51 in Note 19 and page FS-61 in Note 25 under the heading “Income Taxes.”

Other Contingencies Information related to other contingencies is included on page FS-62 in Note 25 to the Consolidated Financial Statements under the heading “Other Contingencies.”

Environmental Matters

The company is subject to various international, federal, state and local environmental, health and safety laws, regulations and market-based programs. These laws, regulations and programs continue to evolve and are expected to increase in both number and complexity over time and govern not only the manner in which the company conducts its operations, but also the products it sells. For example, international agreements (e.g., the Paris Agreement and the Kyoto Protocol) and national (e.g., carbon tax, cap-and-trade, or efficiency standards), regional, and state legislation (e.g., California's AB32 and SB32; other low carbon fuel standards) and regulatory measures (e.g., the U.S. Environmental Protection Agency's methane performance standards) that aim to limit or reduce greenhouse gas (GHG) emissions are currently in various stages of implementation. Consideration of GHG issues and the responses to those issues through international agreements and national, regional or state legislation or regulation are integrated into the company’s strategy, planning and capital investment reviews, where applicable. They are also factored into the company’s long-range supply, demand and energy price forecasts. These forecasts reflect long-range effects from renewable fuel penetration, energy efficiency standards, climate-related policy actions, and demand response to oil and natural gas prices. In addition, legislation and regulations intended to address hydraulic fracturing also continue to evolve at the international, national and state levels. Refer to “Risk Factors” in Part I, Item 1A, on pages 20 through 22 for a discussion of some of the inherent risks of increasingly restrictive environmental and other regulation that