Fostering Opportunities for Resources and Education Spending through Timber Sales Act of 2017 or the FORESTS Act of 2017 This bill directs the Department of Agriculture to establish at least one Forest Active Management Area within each unit of the National Forest System (NFS) designated for sustainable forest management for the production of national forest materials (trees, portions of trees, or forest products) and forest active management revenues (derived from the sale of such materials). The purpose of an Area is to provide a dependable source of: payments to states in which a national forest is situated of 25% of specified forest receipts, to be used for the benefit of public schools and public roads; and economic activity through sustainable forest management for each beneficiary county containing NFS land included within that Area. Forest active management revenues shall be used to make: (1) the 25% payments to states for payment to beneficiary counties for the benefit of public schools and public roads, and (2) deposits into the Knutson-Vandenburg Fund and the salvage sale fund for projects on NFS land. This bill amends the Secure Rural Schools and Community Self-Determination Act of 2000 to extend: through FY2018 authorities for secure payments to states and counties containing federal land, and through FY2020 the authority for special projects on federal land and certain county activities. Receipt by a county of Forest Active Management revenues or stewardship project payments shall be offset against 25% payments to the county. The original method for calculating 25% payments is restored. Beginning October 1, 2015, a state or territorial legislature may not withhold any portion of a 25% payment from the county or counties in which a national forest is situated. The maximum duration of a stewardship end resulting contract under the Healthy Forests Restoration Act of 2003 may extend from 10 to 20 years. The Forest Service or the Bureau of Land Management of the Department of the Interior: shall pay to the county or counties in which the project site is situated 25% of the monies retained from a contract or agreement for a stewardship contracting project on federal land under its respective jurisdiction, and may procure the services of non-federal employees to perform activities necessary to ensure a project for compliance with the National Environmental Policy Act of 1969 and the Endangered Species Act of 1973.