The budding Toronto-based project developer had missed its recent lease-to-option payments, rendering the lease with Placer Mining void.
The company missed a US$400,000 payment in late September and missed a deadline over the weekend to remedy the default.
Amid the crisis, president and CEO Bruce Reid resigned and John Ryan was appointed interim CEO.
Under an agreement announced in March, Bunker Hill had agreed to pay US$20 million to the federal government on Placer Mining's behalf over seven years. The payments were meant to help the US Environmental Protection Agency recover part of the $24 million it had spent on water treatment at the mine.
Bunker Hill said last month it planned to undertake $7.7 million in exploration expenditures to upgrade the 10-12-million-ton exploration target on the Quill and Newgard zones to a compliant format. The historical resource estimate for the entire Bunker Hill property is 9.1 million tons grading 5.08% zinc, 2.35% lead and 40 grams per ton silver.
The stock has lost 94% of its value in the past 12 months, and on Monday closed down 20% at C10c. This gave Bunker Hill a market value of less than C$7 million.