The Headwaters Protection Act of 2025 aims to reauthorize and significantly improve the Water Source Protection Program established under the Healthy Forests Restoration Act of 2003. This legislation expands the program's scope to include adjacent non-Federal land within the same watershed and broadens the definition of eligible partners to include entities like acequia associations, public/private water management entities, and land-grant mercedes. Key improvements include new requirements for watershed protection and restoration projects, which must now protect and restore watershed health, water supply and quality, municipal or agricultural water systems, and related infrastructure, or protect forests from insect infestation and wildfire. The bill establishes new priority criteria for project selection, favoring those that offer risk management benefits against drought, wildfire, and extreme weather, support aquatic restoration, and involve partners with demonstrated capacity, especially for disadvantaged communities. Furthermore, the Act mandates that projects on adjacent land require the express support of the landowner and explicitly states that such projects do not alter land ownership or management. It also facilitates a leadership role for non-Federal partners in project planning and implementation, and allows for the use of existing watershed plans to reduce redundancy in assessments. Financially, the bill substantially increases the authorized appropriations for the Water Source Protection Program from $10 million to $30 million annually for fiscal years 2025 through 2033. It also modifies the non-Federal cost-share requirement to "not less than 20 percent," with a waiver option, and sets aside 10 percent of funds for non-Federal partner technical assistance and capacity-building. Additionally, the bill authorizes $30 million annually for the Watershed Condition Framework improvements, ensuring management activities do not degrade watershed health. Finally, the legislation includes an important clarification that nothing in the Act supersedes or conflicts with State or Federal water law, interstate compacts, or treaty obligations, nor does it authorize any Federal acquisition or control over non-Federal land.