the field reached its peak annual production of 1.7 million barrels. The field operators attempted a cyclic steam recovery process in 1964, but abandoned it two years later. In 1967, Getty merged Tidewater with Missouri Oil, retiring the Tidewater name, and the field continued to produce under the new name. Texaco bought Getty Oil in 1984, and with it the operations on the Zaca field. Vintage Petroleum, then a separate company, purchased the field from Texaco in 1995 during a period in which the major oil companies were divesting many of their onshore California operations and selling them to smaller operators. Greka bought the field from Vintage in August 2002, and remains the principal operator as of 2011, though now under the name HVI Cat Canyon, Inc. On November 1, 2011, Underground Energy, a Santa Barbara-based oil company specializing in extracting petroleum from difficult shale formations, acquired 7,750 acres adjacent to the field on the eastern side – the "Zaca Field Extension Project" – which they stated is estimated to contain over 20 million barrels of combined proved, probable, possible, and prospective reserves. Netherland, Sewell and Associates Inc., an independent resource audit firm, stated their best estimate in their report dated August 23, 2012 Underground Energy's "Zaca Field Extension Project" has 493.2 million barrels of total petroleum initially-in-place on their acreage. This report also stated the company's interests includes 12.3 million barrels of contingent oil resources and 37 million barrels of prospective oil resources. Environmental compliance issues The environmental compliance history of the field includes several risk assessment and remediation orders by the Santa Barbara County Air Pollution Control District (SBCAPCD), and since the purchase by Greka, several significant oil and contaminated water spills, two of which were taken over by the U.S. Environmental Protection Agency. In 1991, the SBCAPCD ordered a Health Risk Assessment (HRA) of operations on the field, which at that time was run by Texaco. The assessment found significant cancer and non-cancer risks from emissions at several locations on the facility. At the time of the next assessment, 1994, the risks had increased, from 29 in a million for cancer to 37 in a million, and in 1998 they had dropped to 22.58 in a million, with a "significance" threshold of 10 in a million. The contaminants driving the risk analysis were polycyclic aromatic hydrocarbons (PAHs) which were produced primarily by internal combustion engines on the