In 2011, the EIA published a report that stated the Monterey Shale in California had 15.4 billion barrels of recoverable oil, or two-thirds of the then estimated recoverable tight oil in the US. The EIA subsequently downgraded its estimate to 13.7 billion barrels in 2013. Post Carbon Institute and PSE Healthy Energy doubted the veracity of these estimates, and I worked with them to assess the EIA’s claims by analyzing available drilling data and the geology of the Monterey formation. In December 2013 they published my report, Drilling California: A Reality Check on the Monterey Shale, which concluded that the EIA’s estimate was vastly overstated. A few months later, the EIA quietly downgraded its estimate by 96% to 600 million barrels, but the revision was picked up by the Los Angeles Times in May 2014.

Yesterday the U.S. Geological Survey (USGS) released a report stating that the mean technically recoverable oil resource in the Monterey was just 21 million barrels, a further 96% downgrade from the revised 2014 EIA estimate.

To put this in perspective a resource which in 2011 the EIA estimated was 15.4 billion barrels—enough oil to meet all of U.S. needs for over two years—has been reduced to 21 million barrels, or enough oil to meet U.S. needs for only 26 hours. The initial estimate caused wildly overblown optimism within industry and government on the energy and economic future of California and major concerns within environmental groups about the effects of fracking to recover these resources on the environment.

Unfortunately, the excessive estimates for the Monterey are not the EIA’s only episode of unfounded optimism. I have since looked at EIA estimates for all major tight oil and shale gas plays in the U.S. and found them highly to extremely optimistic when analyzed in the light of actual drilling and production data (see Drilling Deeper; Shale Gas Reality Check and Tight Oil Reality Check). Nor does it appear that the EIA has learned from its mistakes. In the most recent Annual Energy Outlook, the EIA raised its projections for cumulative oil production from the Bakken Play (the 2^nd largest in the U.S.) by 85%—despite the fact that production in the play is already down more than 5% from its December 2014 high, and would require the production of twice as much oil through 2040 as the 2013 USGS assessment estimated was technically recoverable from the play.

The people of the United States are not well served by unrealistic and overblown forecasts. Future energy supply is a huge concern and realistic forecasts are crucial in formulating energy policy to ensure future sustainability.