Gerald J. Kauffman

This research conducts a benefit-cost analysis of water policies to reach an optimal level of dissolved oxygen (DO) to meet year-round fishable water quality criteria in the Delaware River. A watershed pollutant load model is utilized to estimate marginal cost curves of water quality improvements to meet a more protective year-round fishable standard and annual benefits are defined to achieve future DO criteria in the Delaware River. The most cost-effective DO standard is 4.5 mg/L defined by the point where the marginal benefits of willingness to pay (WTP) for improved water quality equals the marginal costs of pollution reduction. This optimal criteria (4.5 mg/L) can be achieved at a cost of $150 million with benefits ranging from $250 to $700 million/year. While a future DO standard of 4.5 mg/L reflects an economically efficient level of water quality, this DO criteria is less protective than the level of 5–6 mg/L needed to protect anadromous fish such as the Atlantic sturgeon. The policy to reach a DO level of 6 mg/L (at 80% DO saturation) may be difficult to achieve at summer water temperatures that approach 30 °C in the Delaware River at Philadelphia.

Water quality in the Delaware River, USA, has improved significantly since the Federal Water Pollution Control Act (1948), Clean Water Act of 1972, and authorization of the Delaware River Basin Commission Compact in 1961. Initial economic analysis by the Federal Water Pollution Administration in 1966 concluded the multimillion dollar pollution abatement programme would generate $350 million in annual benefits by improving dissolved oxygen levels to fishable standards in the Delaware River. Although water quality in the Delaware has improved substantially, scientists have called for raising the 1960s dissolved oxygen criteria from 3.5 mg/L to 5.0 mg/L to ensure year‐round propagation of anadromous American shad and Atlantic sturgeon. This higher level would also mitigate atmospheric warming resulting in increased water temperatures and sea water incursion, both of which would lead to reductions in dissolved oxygen saturation in the river. Additional economic valuation of this water quality improvement shows direct use benefits in the Delaware River to range from $371 million to $1.1 billion per year. Other economic sectors benefiting from improved water quality include recreational boating ($46–$334 million), recreational fishing ($129–$202 million), agriculture ($8–$188 million), nonuse value ($76–$115 million), viewing/boating/fishing ($55–$68 million), bird watching ($15–$33 million), property value ($13–27 million), water supply ($12–$24 million), commercial fishing (up to $17 million), and navigation ($7–$16 million). Future economic research is needed in the Delaware River watershed to more precisely measure nonuse benefits by public willingness to pay for improved water quality.

The Delaware River has made a marked recovery in the half-century since the adoption of the Delaware River Basin Commission (DRBC) Compact in 1961 and passage of the Federal Clean Water Act amendments during the 1970s. During the 1960s, the DRBC set a 3.5 mg/L dissolved oxygen criterion for the river based on an economic analysis that concluded that a waste load abatement program designed to meet fishable water quality goals would generate significant recreational and environmental benefits. Scientists with the Delaware Estuary Program have recently called for raising the 1960s dissolved oxygen criterion along the Delaware River from 3.5 mg/L to 5.0 mg/L to protect anadromous American shad and Atlantic sturgeon, and address the prospect of rising temperatures, sea levels, and salinity in the estuary. This research concludes, through a nitrogen marginal abatement cost (MAC) analysis, that it would be cost-effective to raise dissolved oxygen levels to meet a more stringent standard by prioritizing agricultural conservation and some wastewater treatment investments in the Delaware River watershed to remove 90% of the nitrogen load by 13.6 million kg N/year (30 million lb N/year) for just 35% ($160 million) of the $449 million total cost. The annual least cost to reduce nitrogen loads and raise dissolved oxygen levels to meet more stringent water quality standards in the Delaware River totals $45 million for atmospheric NOX reduction, $130 million for wastewater treatment, $132 million for agriculture conservation, and $141 million for urban stormwater retrofitting. This 21st century least cost analysis estimates that an annual investment of $50 million is needed to reduce pollutant loads in the Delaware River to raise dissolved oxygen levels to 4.0 mg/L, $150 million is needed for dissolved oxygen levels to reach 4.5 mg/L, and $449 million is needed for dissolved oxygen levels to reach 5.0 mg/L.

The Delaware River has made a marked recovery in the half-century since the adoption of the Delaware River Basin Commission (DRBC) Compact in 1961 and passage of the Federal Clean Water Act amendments during the 1970s. During the 1960s, the DRBC set a 3.5 mg/l dissolved oxygen criteria for the river based on an economic analysis that concluded a waste load abatement program designed to meet fishable water quality goals would generate significant recreation and environmental benefits. Scientists with the Delaware Estuary Program have recently called for raising the 1960s DO criteria along the Delaware River from 3.5 mg/l to 5.0 mg/l to protect anadromous American shad and Atlantic sturgeon and address the prospect of rising temperatures, sea levels, and salinity in the estuary. This research concludes through a marginal abatement cost (MAC) analysis that it would be cost effective to raise DO levels to meet a more stringent standard by prioritizing agricultural conservation and wastewater treatment investments in the Delaware River watershed to reduce 90% of the pollutant load 13.6 million kg/year of nitrogen (30 million lb/year) for $160 million at 35% of the $449 million annual cost. The annual least cost to reduce nitrogen loads and raise dissolved oxygen levels to meet more stringent water quality standards in the Delaware River totals $45 million for atmospheric NOX reduction, $130 million for wastewater treatment, $132 million for agriculture conservation, and $141 million for urban stormwater retrofitting. This 21st century least cost analysis estimates that $50 million/year is needed to reduce pollutant loads in the Delaware River to raise dissolved oxygen levels to 4.0 mg/l, $150 million/year is needed to reach 4.5 mg/l, and $449 million/year is needed to reach 5.0 mg/l.

Through modernization of horizontal drilling and hydraulic fracturing technology, natural gas has become a plentiful, inexpensive, and relatively clean-burning domestic resource that provides a quarter of U.S. electric power needs and promises to reduce reliance on foreign oil. The 350-million-year-old Marcellus Shale Formation covers 54,000 mi² in West Virginia, Ohio, Maryland, Pennsylvania, and New York. It is thought to be the third largest natural gas reserve in the world. Approximately 9% of the Marcellus shale lies in the upper third of the Delaware Basin in a watershed that supplies drinking water to 16 million people (5% of the U.S. population) in Delaware, New Jersey, New York, and Pennsylvania, including New York City and Philadelphia, the first and seventh largest metropolitan economies in the nation. Almost ¾ of the Marcellus shale lies in New York and Pennsylvania where drilling has generated millions of jobs and billions of dollars of wages in Pennsylvania alone. In the Delaware Basin, Marcellus shale gas drilling is at the center of a contentious energy-water policy debate that pits gas companies, land owners, and rural towns interested in jobs versus environmental groups, water utilities, and fishermen concerned about the impacts of hydraulic fracturing on the quality and quantity of water supplies. Federal, state, regional, and local agencies are reviewing policies and standards to oversee Marcellus shale gas drilling. The Environmental Protection Agency oversees natural gas drilling, however, federal laws such as the Clean Water Act and Safe Drinking Water Act exempt portions of the hydraulic fracturing process from regulation. A drilling moratorium remains in the Delaware Basin after a November 2011 vote of the DRBC Commissioners was postponed. The governor of New York continues a ban on horizontal natural gas drilling pending approval of an environmental impact statement (EIS). Pennsylvania Act 13 established a 5% drilling fee and set horizontal drilling buffers. Buffers set by proposed DRBC and NYSDEC rules, recently enacted Pennsylvania Act 13, and drilling bans in four New York towns would exclude 2,363 mi² of the 4,940 mi² Marcellus shale region in the Delaware Basin from natural gas drilling, leaving 2,577 mi² (52% of the area) available for extraction. With buffers in place to shield sensitive water resources from hydraulic fracturing, the estimated economic value of 4.0 tcf of potentially recoverable Marcellus shale gas in the basin at the 2012 wellhead price is $425 million per year, or three times less than the value at the 2008 price. In the Delaware Basin, the annual economic value of natural resources ranges from $425 million for potentially recoverable Marcellus shale gas to $942 million for river recreation, $2.8 billion for drinking water, and $4.2 billion for forest ecosystems. The annual value of drinking water, forests, and recreation that depend on renewable resources in the Delaware Basin is higher than the value of potentially recoverable Marcellus shale gas, a nonrenewable resource. The Marcellus shale energy-water policy debate should be considered in the context that natural gas, water, forests, and river recreation are significantly valuable Delaware Basin resources. While Marcellus shale gas is a voluminous, inexpensive, and clean-burning domestic energy source, its extraction relies on the safe use of water for hydraulic fracturing. If natural gas is to be a key part of the nation's energy economy, then the most stringent Marcellus shale gas drilling standards should be adopted to protect the invaluable water resources of the Delaware Basin (and other watersheds like it) that support multibillion dollar drinking water, forest, and river recreation economies.

The frequency and severity of drought in the Delaware Basin between 1600 and 2002 are examined using the Palmer Drought Severity Index (PDSI) estimated from tree ring data and correlated with reconstructed annual low flows. In the Delaware Basin, the most severe drought in nearly a century occurred during 1995–2002 as the Brandywine River, Delaware's largest surface water supply, ran dry at its mouth and declined to the lowest flow on record since 1912. To evaluate the long‐term context of the 1995–2002 droughts given a variable hydroclimate, tree ring and PDSI data were correlated to reconstruct flows along the river to 1600, the beginning of European exploration to the Delaware Bay. Reconstructed PDSI and low flows were fit using general extreme value (GEV) distributions to estimate drought frequency. Some variability is present as reconstructed low flows tend to overestimate recorded streamflow in severe dry years, a finding reported by others. Some uncertainty appears in the correlations as the coefficient of multiple determination (CRSQ) between recorded and estimated PDSI from tree ring data is 0.50–0.54, a level of variance considered to be “quite good,” and the coefficient of determination (r²) between PDSI and low flow is 0.52. Given the uncertainty, PDSI and reconstructed low flow data both agree that the most extreme drought in 400 years occurred during 1635, and the drought of 1995–2000 was historically extreme with differences only in the degree of severity. On the basis of PDSI, the 2002, 1999, and 1995 droughts were the sixth, twelfth, and seventeenth most severe in 400 years with frequencies of once every 50, 33, and 16 years, respectively. Based on low flow, the 2002, 1999, and 1995 droughts were the second, fourth, and ninth most severe since 1600 with frequencies of once every 200, 100, and 50 years, respectively. The record drought of 2002 has a low probability of reoccurring in any given year (2.0% by PDSI and 0.5% by low flow), but droughts nearly as severe have occurred during the 1630s, 1680s, 1820s, 1840s, 1860s, 1930s, 1940s, and 1960s. Increased intensities of drought low flows in Delaware during the late twentieth century through 2002 were coincident with population growth, watershed urbanization, and atmospheric warming although these associations were not correlated and further study is needed. Over 400 years of tree ring, PDSI, and reconstructed streamflow data indicate that the Delaware Basin record drought of 1995–2002 was a historically severe event with important implications for water supply and drought management. Droughts more severe than the record 2002 event have occurred in the past, and droughts may become even more intense should watershed urbanization and atmospheric warming continue in the future.

In 1940, the tidal Delaware River was “one of the most grossly polluted areas in the United States.” During the 1950s, water quality was so poor along the river at Philadelphia that zero oxygen levels prevented migration of American shad leading to near extirpation of the species. Since then, water quality in the Delaware Basin has improved with implementation of the 1961 Delaware River Basin Compact and 1970s Federal Clean Water Act Amendments. At 15 gages along the Delaware River and major tributaries between 1980 and 2005, water quality for dissolved oxygen, phosphorus, nitrogen, and sediment improved at 39%, remained constant at 51%, and degraded at 10% of the stations. Since 1980, improved water-quality stations outnumbered degraded stations by a 4 to 1 margin. Water quality remains good in the nontidal river above Trenton and, while improved, remains fair to poor for phosphorus and nitrogen in the tidal estuary near Philadelphia and in the Lehigh and Schuylkill tributaries. Water quality is good in heavily forested watersheds (>50%) and poor in highly cultivated watersheds. Water quality recovery in the Delaware Basin is coincident with implementation of environmental laws enacted in the 1960s and 1970s and is congruent with return of striped bass, shad, blue crab, and bald eagle populations.

Field measurements indicate a correlation between increased impervious cover and decreased stream base flow in and near the White Clay Creek Wild and Scenic River watershed near Newark, Del. A stream base flow monitoring network was established in 19 watersheds near the University of Delaware campus. The watersheds have land uses varying from heavily forested to highly urbanized with impervious cover ranging from 3 to 44%. Using geographic information system land use mapping, watershed impervious cover was estimated based on the ratio of pavement and roof area for each land cover condition. Stream base flows were calculated using the continuity equation (Q=νA) from velocity and channel cross-section area measurements recorded on 5 days during 2006 and 2007. Results from all five events indicate increased watershed impervious cover correlates with decreased stream base flows. For the five events, the coefficients of determination ( R2 ) based on linear regression of impervious cover and base flow data are ...