題目：Internalizing Externalities: Disclosure Regulation for Hydraulic Fracturing, Drilling Activity and Water Quality

摘要：The rise of shale gas and tight oil development has triggered a major debate about hydraulic fracturing (HF). In an effort to mitigate risks from HF, especially with respect to water quality, many U.S. states have introduced disclosure mandates for HF wells and fracturing fluids. We use this setting to study whether targeting activities with dispersed environmental externalities with disclosure regulation reduces their environmental impact. We find significant improvements in water quality, examining salts that are considered signatures for HF impact, after the disclosure mandates are introduced. We document effects along the extensive and the intensive margin, though most of the improvement comes from the latter. Supporting this interpretation, we find that, after the disclosure mandates, operators pollute less per unit of production, use fewer toxic chemicals, and cause fewer spills and leaks of HF fluids and wastewater. We also present evidence that disclosure enables public pressure, which facilitates internalization.

1.主要故事

基于各州引入對于頁巖氣、致密油的水力壓裂開采方法的披露監(jiān)管這一場景，采用錯層DID/漸進DID方法，檢驗這種披露監(jiān)管的Real effects，主要focus對于水質(zhì)的影響。發(fā)現(xiàn)相較于沒有采用HF州，采用HF的州在相關(guān)披露監(jiān)管后比披露監(jiān)管后水質(zhì)得到了提升。文章進一步探究這種改變來源于Extentive Margin（需要加強披露后減少鉆井數(shù)量）還是Intensive Margin（降低per-well的污染水平），實證檢驗發(fā)現(xiàn)主要是來自于Intensive Margin。最后，文章還進一不檢驗了公眾壓力發(fā)揮的作用，披露監(jiān)管可能導致利益相關(guān)者（環(huán)保組織，當?shù)厣鐓^(qū)）對于鉆井活動的關(guān)注度，從而影響HF運營商的行為。確實發(fā)現(xiàn)，受到更多公眾關(guān)注的HF運營商，披露監(jiān)管所帶來的影響更大。

2.重要Tests

（1）Main Results

（2）Placebo Analyses

Two “placebo” tests. First, we examine changes in the concentration of analytes that are not specific to HF water impact and unlikely to be directly affected by HF activity.

Second, we examine changes in the four HF-specific ion concentrations around the disclosure mandates, but in watersheds with conventional drilling

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（3）Extensive and the Intensive Margin（P26）

The evidence provided so far points to an increase in water quality after the introduction of the disclosure mandates. We now turn to examine through which margin such an effect occurs.

This increase in water quality may come from less HF activity in the post-disclosure period relative to the pre-disclosure period (extensive margin) and/or from HF operators shifting to a less-water polluting technology (intensive margin).

Over the two margins, we obtain that around 89 percent of the decrease comes from the intensive margin.(P29)

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（4）Analyses of the Changes in HF Operators’ Practices

?First, we examine whether the decline in water impact per new HF well comes at the expense of less productive wells after the disclosure mandates.

Second, we examine whether HF operators start to employ less hazardous chemicals in the post-disclosure period.

Third, we examine the effect of the disclosure regulation on the probability of HF-related incidents.

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Our last set of analyses explore the role of public pressure in making disclosure regulation effective. As discussed earlier, a likely channel is that disclosure regulation enables public pressure from local environmental groups, local communities and the general public on HF operators