Uncertainty vs. Action Our understanding of the winter ozone issue has many gaps. These gaps hinder our ability to solve the problem efficiently and effectively. Research is the key to overcoming this challenge. More research is needed and will be needed for many years. BUT, we have enough information right now to make some decisions that will reduce winter ozone with little risk of wasting time and money. 1

What We Know and What We Don’t Know The basic drivers that lead to wintertime ozone are known with certainty. 2

What We Know and What We Don’t Know We know with certainty that almost all local organic compound emissions and a strong majority of NOx emissions are from oil and gas. 3

What We Know and What We Don’t Know We know a lot about WHERE high ozone occurs and WHY it has the distribution it does (though the spatial distribution may be changing) 4

What We Know and What We Don’t Know 2014 Air Agencies Oil and Gas Emissions Inventory Participation A collaboration between UDAQ, Ute Tribe, and EPA Approximately 60 companies contacted (some letters returned, other companies no longer operating) 31 Workbooks received Covers approximately 96% of 2014 producing or shut- in APIs in Uintah and Duchesne counties 5

What We Know and What We Don’t Know We have a basic understanding of the SOURCES of oil and gas emissions. For non-road and on-road :2014 NEI Summary (EPA website) * Couldn't find non-Winter UDAQ estimates, but within range of 2014 UDAQ Workbook estimates 6

What We Know and What We Don’t Know We have a basic understanding of the SOURCES of oil and gas emissions. 7

What We Know and What We Don’t Know 8

What We Know and What We Don’t Know 9

What We Know and What We Don’t Know Inventory Information Gaps Reliance on national emission factors (EFs) – e.g. AP-42 Impact of composition on emission estimates Hard to quantify categories like fugitive emissions % Control vs. Control Efficiency Ideal operating vs. real world operating Equipment Types Still Absent in Inventory – Reciprocating Compressor Venting, Centrifugal Compressor venting, well testing venting and flaring, associated gas venting and flaring from prod. Hydrocarbons, EOR Injection Pump Blowdown, Gathering Pipeline Equipment Leaks, Pipeline Blowdowns, Methanol Tanks, Pigging Pipelines 10

What We Know and What We Don’t Know The 2014 Air Agencies Oil and Gas Emissions Inventory is the most comprehensive oil and gas inventory for the basin to date. But…. We still see discrepancies between bottom up inventories like ours and top-down inventories. The reasons for the discrepancies between the two inventory approaches are not clear in many cases. We are still unable to model high ozone levels using bottom up inventoried values. 11

What We Know and What We Don’t Know We have a basic understanding of the COMPOSITION of emissions from different oil and gas sources. Key areas of poor understanding: Composition information is generalized and not tested against field measurements Composition information about carbonyls (e.g., formaldehyde) and methanol is very poorly understood, even though these are very important ozone precursors 12

What We Know and What We Don’t Know We don’t have a good understanding of whether inventoried NOx emissions are too high or too low. Competing modeling studies make both claims. 13

What We Know and What We Don’t Know The best estimates made so far indicate that reducing emissions of NOx and organics would both be effective, but this has never been done basin-wide. Edwards et al., 2014 14

What We are Learning About Right Now Emissions Investigations of several different source types Produced water Subsurface leaks Well sites (detailed emiss. composition) Fugitive emissions from tanks (particular focus on methanol and aldehydes) High-density organic compound measurements—coupled with modeling—to verify inventory at fine scale Investigating inter-annual changes in ambient NOx and organics Investigating snowpack processing of organics 15

What We are Digging Into Right Now Modeling Improving accuracy of meteorological and chemical models with data assimilation (ground-based and satellite data) Incorporating new measurement data into inventory and model (including composition) Verifying models using ground-based and satellite measurement data Developing methods for ozone forecasting 16

Links DAQ All of UDAQ’s research products to date: https://deq.utah.gov/air-quality/utah-division-of-air-quality-applied-research Summary of all of the Uinta Basin Winter Ozone Studies (UBWOS) completed in the Basin from 2011-2014 https://deq.utah.gov/legacy/destinations/u/uintah-basin/ozone/strategies/index.htm UDAQ’s main Uinta Basin page, including links to the oil and gas emissions inventory https://deq.utah.gov/legacy/destinations/u/uintah-basin/index.htm Ulend camera lending program page: http://ulend.utah.gov USU All of USU’s research products to date: http://binghamresearch.usu.edu/reports Cumulative summary of all UB air quality research to date (including other institutions): https://binghamresearch.usu.edu/cumulativeresearchsummary Ozone Alert sign-up page: http://binghamresearch.usu.edu/OzoneAlert Map view of all available real-time air quality data in UB: http://ubair.usu.edu 17