Marginal Well Production Preservation and Enhancement Act

Marginal Well Production Preservation and Enhancement Act - Amends the Internal Revenue Code to: (1) increase to 27.5% the percentage depletion allowance for domestic crude oil and natural gas production from marginal properties; (2) extend through 2008 the temporary suspension of the taxable income limit with respect to marginal production of crude oil and natural gas; and (3) accelerate to three years the recovery period of qualified tertiary injectant property for depreciation purposes.

Amends the Clean Air Act with respect to emissions from small oil and gas exploration and production-related equipment.

Amends the Federal Water Pollution Control Act to: (1) amend the definition of "wastewater treatment facility" to include produced water from an oil production facility; and (2) require the Administrator of the Environmental Protection Agency (EPA) to establish cost-effective minimal requirements for the prevention of oil and hazardous substance discharges for small facilities with oil storage capacities of less than 50,000 gallons at which no single tank exceeds a nominal capacity of 21,000 gallons.