The Cost Of Clean Water In The Delaware River Basin (USA)
waterArticleThe Cost of Clean Water in the Delaware RiverBasin (USA)Gerald J. KauffmanIDWater Resources Center, School of Public Policy and Administration, University of Delaware,Newark, DE 19716, USA; jerryk@udel.edu; Tel.: 1-302-831-4929Received: 22 September 2017; Accepted: 8 January 2018; Published: 24 January 2018Abstract: The Delaware River has made a marked recovery in the half-century since the adoptionof the Delaware River Basin Commission (DRBC) Compact in 1961 and passage of the FederalClean Water Act amendments during the 1970s. During the 1960s, the DRBC set a 3.5 mg/Ldissolved oxygen criterion for the river based on an economic analysis that concluded that a wasteload abatement program designed to meet fishable water quality goals would generate significantrecreational and environmental benefits. Scientists with the Delaware Estuary Program have recentlycalled for raising the 1960s dissolved oxygen criterion along the Delaware River from 3.5 mg/L to5.0 mg/L to protect anadromous American shad and Atlantic sturgeon, and address the prospectof rising temperatures, sea levels, and salinity in the estuary. This research concludes, through anitrogen marginal abatement cost (MAC) analysis, that it would be cost-effective to raise dissolvedoxygen levels to meet a more stringent standard by prioritizing agricultural conservation and somewastewater treatment investments in the Delaware River watershed to remove 90% of the nitrogenload by 13.6 million kg N/year (30 million lb N/year) for just 35% ( 160 million) of the 449 milliontotal cost. The annual least cost to reduce nitrogen loads and raise dissolved oxygen levels to meetmore stringent water quality standards in the Delaware River totals 45 million for atmosphericNOX 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 thatan annual investment of 50 million is needed to reduce pollutant loads in the Delaware River toraise dissolved oxygen levels to 4.0 mg/L, 150 million is needed for dissolved oxygen levels to reach4.5 mg/L, and 449 million is needed for dissolved oxygen levels to reach 5.0 mg/L.Keywords: river basin; water quality; water pollution; economic valuation1. IntroductionNutrient pollution due to high loads of nitrogen and phosphorus causes costly impacts onthe tourism, commercial fishing, recreation, hunting, real estate, and water treatment sectors of theeconomy [1]. Noting that 50% of the nation’s streams have medium to high nutrient levels and 78% ofcoastal waters experience eutrophication, the Environmental Protection Agency (EPA) has urged statesto adopt numeric nutrient criteria to reduce nitrogen and phosphorus loads on U.S. waters [2].Nutrient load reduction costs in the nation’s waters are significant and range from 35 million/year inthe 16,500 km2 Wisconsin Fox-Wolf River watershed [3] to 203 million/year in the 26,200 km2 ConnecticutRiver/Long Island Sound Basin [4]. The Chesapeake Bay Program [5] estimated that restoration of the166,000 km2 Chesapeake Bay watershed could cost 1 billion/year. Rabotyagov et al. [6] estimated acost of 1.8 billion/year to reduce nutrient loads and increase dissolved oxygen levels in the 492,000 km2Upper Mississippi River Basin. Lyon and Farrow [7] reported to the EPA that the Federal Clean WaterAct stormwater programs could cost up to 14 billion/year nationwide.The Interstate Commission on the Delaware River Basin [8] once called the Delaware River nearPhiladelphia “one of the most grossly polluted areas in the United States.” In 1961, President JohnWater 2018, 10, 95; doi:10.3390/w10020095www.mdpi.com/journal/water
Water 2018, 10, 952 of 21F. Kennedy and the governors of Delaware, New Jersey, New York, and Pennsylvania signed theDelaware River Basin Commission (DRBC) Compact as one of the first models of Federalism or sharedpower in water management between the Federal government and the states [9]. For over half acentury, the DRBC has been empowered by this compulsory 1961 Federal/state compact to overseewater pollution control programs on the Delaware River [10,11].Water quality has been impaired by nutrient pollution [12–16] but the estuary has recovered in thelast several decades due to restoration efforts by DRBC, EPA, and the states [17–19]. A century-longwater quality record reconstructed by Sharp [20] indicates that the tidal Delaware has made one ofthe most extensive recoveries of any estuary in the world as dissolved oxygen levels declined to zeroduring the 1950s and 1960s and increased to near 400 µmol/L by the turn of the 21st century.While pollutant loadings have decreased and water quality has measurably improved in theDelaware Estuary since the adoption of the 1961 DRBC Compact, dissolved oxygen levels still do notfully meet the criterion of 3.5 mg/L during the summer when dissolved oxygen saturation declineswith warming water temperatures. Scientists with the Delaware Estuary Program and the DRBC havediscussed setting more rigorous dissolved oxygen criteria along the tidal Delaware River (to at least5.0 mg/L) to protect the year-round propagation of anadromous fish such as the American shad andAtlantic sturgeon [21,22]. More stringent dissolved oxygen criteria would also address the prospectof atmospheric warming and rising sea levels that are projected to increase water temperatures,raise salinity, and further depress dissolved oxygen saturation.While dissolved oxygen levels have recovered over the last half-century, little is known aboutmodern costs to restore the Delaware River to meet fishable water quality standards. The objectives ofthis research are to estimate the costs of investments to reduce pollutant loads and restore the DelawareRiver to meet more protective year-round fishable dissolved oxygen criteria in accordance with DRBC,EPA, and state water quality standards.2. The Delaware RiverWhile just the 33rd largest river in the United States, the Delaware River is the longest undammedriver east of the Mississippi, extending 390 mi (628 km) from the 3000 ft (970 m) high Catskill Mountainsin New York State to the mouth of the Delaware Bay at Cape May, New Jersey. The river is fed by216 streams including its two largest tributaries (the Schuylkill and Lehigh River) and drains 13,539 mi2(35,077 km2 ) in Delaware, Pennsylvania, New Jersey, New York, and a small part of Maryland.The Delaware Basin covers just 0.4% of the continental U.S., yet supplies drinking water to 5% ofthe nation’s population and the first (New York City) and seventh (Philadelphia) largest metropolitaneconomies in the nation [23]. Over 16 million people rely on the Delaware Basin for drinking water,including 8.2 million people who live in the watershed and 8 million people who live outside the basinin New York City and central New Jersey. Between 2000 and 2010, the population in the DelawareBasin increased by half a million people, an amount equal to the combined population of the cities ofCamden, Trenton, and Wilmington.The Delaware Estuary extends 130 mi (208 km) from the Atlantic Ocean to the head of tide atTrenton [24]. High nutrient loads discharged from tributaries near Philadelphia and rural streams alongthe bay are diluted by saltwater as the estuary widens toward the mouth of the bay [13]. The DelawareEstuary recirculates every 8 days (Table 1) with half mixing with freshwater from the Delaware Riverat Trenton, Schuylkill, Lehigh, Brandywine, and smaller tributaries and the other half from the AtlanticOcean [17]. The estuary is relatively turbid with a light extinction coefficient of 0.3–7.0 [25].
Water 2018, 10, 953 of 21Water 2018, 10, x FOR PEER REVIEW3 of 20Table 1. Characteristics of the Delaware River [17,25].Table 1. Characteristics of the Delaware River [17,25].CharacteristicCharacteristic(km2 )DrainageArea Area (km2)DrainagePopulation(2010) (2010)PopulationTotal Length (km)Total Length (km)Tidal Length /EstuaryEstuary Recirculation (days) RatioEstuary RecirculationLight ExtinctionCoefficient (days)Light Extinction 0628628155155 1818 88 0.3–7.00.3–7.0The DRBC [26,27] classifies the Delaware River and Bay according to 10 nontidal and tidal waterThe DRBC [26,27] classifies the Delaware River and Bay according to 10 nontidal and tidal waterquality management zones based on (a) Agricultural, Industrial, and Public Water Supply; (b) Wildlife,quality management zones based on (a) Agricultural, Industrial, and Public Water Supply; (b)Fish and Aquatic Life; (c) Recreation (Swimming, Boating, Fishing, Wading); (d) Navigation; andWildlife, Fish and Aquatic Life; (c) Recreation (Swimming, Boating, Fishing, Wading); (d) Navigation;(e) Waste Assimilation designated uses (Figure 1). In the tidal Delaware, the summer dissolved oxygenand (e) Waste Assimilation designated uses (Figure 1). In the tidal Delaware, the summer dissolvedcriterionfromvaries3.5 mg/Land4 (fromRancocaspastCreekPhiladelphiato 3inZones3 and4 (fromCreekRancocaspast Philadelphiatoto areCanal).MinimumWilmington) to 4.5 mg/L in Zone 5 (from Wilmington to the Chesapeake & Delaware dissolvedCanal).oxygencriteriaare 6.5 mg/Lduringspringfallduringin Zones2 through5 e 6.5andmg/Lspringand fallin allowZones for2 through5 toallowandof residentanadromousfish. and anadromous fish.forpropagationseasonal spawningand andpropagationof residentFigure1.1.DelawareDelawareRiverRiver waterwater qualityquality managementFiguremanagementzoneszones[27].[27].
Water 2018, 10, 954 of 21Water 2018, 10, x FOR PEER REVIEW4 of 20Despite high nutrient loading, the Delaware Estuary does not exhibit classic eutrophicationsymptomsof hypoxiaor algalbloomstheas Delawareobserved inthe nearbyChesapeakeBay. Algalblooms areDespitehigh nutrientloading,Estuarydoes notexhibit classiceutrophicationinhibitedby theassimilativecapacityof aswetlandsthatthe DelawareBay andlow bloomslight levelssymptomsof hypoxiaor algalbloomsobservedin rimthe nearbyChesapeakeBay.byAlgalare intheinhibitedwell-flushedturbid DelawareEstuary.Through17 miBay(27 andkm)bymouthof Delawareby theandassimilativecapacity ofwetlandsthat rimthethewideDelawarelow lightlevelsBay,Atlantic Oceansignificanttidalflushing,algalthatcause fishin the well-flushedandcontributesturbid DelawareEstuary.Throughthethuswidelimiting17 mi (27km)bloomsmouth ofDelawarekillsexceptduring Oceanan occasionalspringbloom inthe flushing,mid estuaryBay,the ng algal blooms that causefishDuringkills exceptduringan occasionalspringbloomin themid estuarythe 1960swhenthe river wasanoxicanda decadebefore[17].the 1970s Federal Clean beforethe1970s FederalClean WaterAct Amendments, the DRBC imposed waste load allocations on 80 dischargersand adoptedthe ate water quality standards along the Delaware River. The Federal Water Pollutioninterstate waterquality standardsalongthe ProgramDelaware[28–31]River. TheFederalWater PollutionAdministration(FWPCA)and HarvardWaterissuedan economicreport inControl1966 –31]issuedaneconomicreportin1966concluded that water supply and recreation benefits due to improved water quality in the enefitsduetoimprovedwaterqualityintheRiver would exceed water pollution control costs [32–35].Delaware River would exceed water pollution control costs [32–35].The 1966 FWPCA study estimated pollutant reduction costs ranged from 150 million to achieve aThe 1966 FWPCA study estimated pollutant reduction costs ranged from 150 million to achievedissolved oxygen level of 2.5 mg/L to 490 million to achieve a dissolved oxygen criterion of 4.5 mg/La dissolved oxygen level of 2.5 mg/L to 490 million to achieve a dissolved oxygen criterion of 4.5 mg/Lwith diminishing marginal costs of improvement occurring at dissolved oxygen of 3.0 mg/L (Table 2).with diminishing marginal costs of improvement occurring at dissolved oxygen of 3.0 mg/L (Table 2).Thomann [33] estimated that shad passage would achieve 80% survival if dissolved oxygen improvedThomann [33] estimated that shad passage would achieve 80% survival if dissolved oxygen improvedfrom 0.5 mg/L in 1964 to a future level of 3.0 mg/L. In 1967, the DRBC considered this economicfrom 0.5 mg/L in 1964 to a future level of 3.0 mg/L. In 1967, the DRBC considered this economic analysisanalysisset thedissolvedcurrent dissolvedoxygen3.5Delawaremg/L inRiverthe nearDelawareRiver tonearand setandthe currentoxygen standardof standard3.5 mg/L inofthePhiladelphiaPhiladelphiasupportand fallmigration offish.anadromousfish.DRBCIn 1968,theprescientlyDRBC quitesupport thetospringandthefallspringmigrationof anadromousIn 1968, ted that the waste load abatement plan would remove 85% to 90% of carbonaceous BOD andBODandboost dissolvedoxygennearmg/L at Philadelphiaboostdissolvedoxygen fromnearfromzero to4.0 zeromg/Ltoat4.0Philadelphia(Figure 2). (Figure 2).Figure 2. Delaware River Basin Commission (DRBC) dissolved oxygen criteria along the DelawareFigure 2. Delaware River Basin Commission (DRBC) dissolved oxygen criteria along the DelawareEstuary in 1968 [22].Estuary in 1968 [22].Table 2. Costs to meet water quality objectives in the Delaware Estuary [28].Table 2. Costs to meet water quality objectives in the Delaware Estuary [28].ObjectiveObjectiveSet /CODTotal CostsCostsMarginalBOD/COD ResidualOxygen CriteriaPollution( 1964)Costs( 1964)CriteriaPollutionRemoval( 1964)( ( M/Year)(mg/L)( M/Year) ( M/Year)( M/Year)4.5100,00045,36092–98%490160–2604.5 4.0100,00092–98%490160–260200,000 45,36090,72090%230–330100–1504.0 3.0200,00090%230–330100–150500,000 90,720226,80075%130–18030–30800,000 226,800362,88050%100–15070–1203.0 2.5500,00075%130–18030–300.5status us quo300%Survival% ssolved oxygen levels in the Delaware Estuary vary by water temperature, sunlight, winds,Dissolvedoxygenlevelsthe DelawareEstuarybyDelawarewater temperature,sunlight,winds,and pollutantloads[1]. By2010,indissolvedoxygenlevelsvaryin theRiver at BenFranklinBridgeand pollutant loads [1]. By 2010, dissolved oxygen levels in the Delaware River at Ben Franklin Bridge
Water 2018, 10, 955 of 21at PhiladelphiaexceededWater 2018, 10, xmostlyFOR PEERREVIEW the criterion except for violations below 3.5 mg/L during5 ofthe20 hotWater months2018, 10, x FORPEER throughREVIEW August (Figure 3). During warm summers, 0.5% of readings5 of 20sincesummerof JunePhiladelphiamostlyexceededthe criterionfor violationsbelow3.5 mg/Lduringthe hotRiver2000 atdidnot meet the3.5 mg/Lcriterion.In Julyexceptand August,dissolvedoxygenin theDelawareat Philadelphiamostlyexceededthe criterionexceptfor violationsbelow ughAugust(Figure3).Duringwarmsummers,ofreadingsat Philadelphia occasionally declined below the 3.5 mg/L criterion (46% dissolved oxygen ).Duringwarmsummers,0.5%ofreadingssincedid temperaturesnot meet the 3.5approachedmg/L criterion.August,dissolvedoxygenin the DelawareRiver CJuly F C, dissolvedwhen2000water30Inor and86(Figure4). At 30oxygenis ust,dissolvedoxygenintheDelawareRiverat Philadelphia occasionally declined below the 3.5 mg/L criterion (46% dissolved oxygen saturation)saturatedat 7.54 mg/Land 80%declinedsaturated at 6themg/L;mg/Ltherefore,whenwatertemperaturesrise to 30 C,at ensaturation)whenwater temperaturesapproachedbelow30 C or 3.586 F (Figure4). At30 C,dissolvedoxygenis 100%a futureDRBCdissolvedoxygen standardthan5 res30higher C86 F (FigureAt 30saturation) C, dissolvedoxygensaturatedat 7.54mg/L andapproached80% saturatedat or6 mg/L;therefore,whenwatertemperaturesrise 100%to ummer.saturatedat7.54mg/Land 80%saturatedatthat6 mg/L;therefore,riseproveto 30 C,a futureDRBCdissolvedoxygenstandardhigherthan 5 whenmg/L water(66% temperaturessaturation) may edifficult to achieve given the warm water temperatures that occur during tScientists on the Delaware Estuary Program Science and Technical Advisory Committee havelevelScientistsonDelawareEstuaryProgramand Technicalhaveof 3.5recommendedmg/Lto at least5.0mg/LraiseinZones3 anddissolved4Sciencefrom heDRBCthe fishableoxygenstandardfrom theCommitteecurrentlevelof oxygenstandardfromthecurrentlevelof the3.5 mg/Lto at least5.0 mg/Lin dissolvedZones 3 and4 fromcriterionPhiladelphiaWilmington,giventhat theliteraturesuggeststhat thecurrentoxygenof 3.5tomg/Lis too lowto softhatthe currentshaddissolvedoxygen criterion3.5 mg/Ltoo low to supportthe thatyear-roundsurvivalanadromousand sturgeon[36,37].ofSecorandisGunderson[38] foundliterature suggeststhatthe current dissolvedoxygencriterionof3.5 andmg/Lis too low [38]to supportthe 7].SecorGundersonfoundthatjuvenile Atlantic sturgeon may suffer over 50% mortality at 25 C (77 F) when dissolved oxygen cshortnosesturgeon maysuffer over50% mortalityat 25 C (77when F) whendissolvedoxygenis3.5 mg/L.Juvenilesturgeonare proneto 50% mortalitydissolvedoxygendeclinesjuvenilemaysuffer over50% mortalityat 25 C (77 F) ywhenoxygendeclines C [39]. In 2017, the DRBC passed a resolution authorizing basin commissionbelow3.0mg/Lat 25 alitywhendissolvedoxygendeclinesbelow 3.0 mg/L at 25 C [39]. In 2017, the DRBC passed a resolution authorizing basin commissionscientistsbeginreviewingwaterqualityto determinewhetherdissolvedcommissionoxygen criteriabelowto3.0mg/Lat 25 C [39].In2017,theregulationsDRBCpasseda aterqualityregulationsdeterminewhether basindissolved herleveltoprovidemoreprotectionscientiststo beginreviewingwaterquality3.5regulationsto determinedissolvedoxygencriteriashouldbe increasedfromthe currentmg/L to a higherlevel to whetherprovide moreprotectionof ofcriteria shouldbespawningincreasedfromthe current3.5 mg/L to aoflevel to provide more protection ndpropagationtheanadromous fish spawning and year-round propagation of the fishery.Figure 3. Mean Daily Dissolved Oxygen (DO) at Ben Franklin Bridge along Delaware River.Figure3. MeanDailyDissolvedat er.Figure3. MeanDailyDissolvedOxygenOxygen (DO)(DO) atalongDelawareRiver.Figure 4. Water temperature/dissolved oxygen along the Delaware River.Figure4. Watertemperature/dissolved oxygentheDelawareRiver.Figure4. areRiver.
Water 2018, 10, 956 of 213. Research ObjectivesWhile dissolved oxygen levels have recovered over the last half-century, little is known aboutmodern costs to restore the Delaware River to meet fishable water quality standards. The objectivesof this research are to estimate the costs of investments to reduce pollutant loads and restore theDelaware River to meet more protective year-round fishable dissolved oxygen criteria in accordancewith the Delaware River Basin Commission, Environmental Protection Agency, and state waterquality standards.4. MethodsWith the following research, we estimate the modern costs of the nitrogen pollutant loadreductions necessary to increase dissolved oxygen from the current criterion (3.5 mg/L) to a future,more stringent water quality standard (5.0 mg/L) in the Delaware River. To estimate the mostcost-effective combination of nitrogen load reductions, we (1) quantified nitrogen loads in the DelawareBasin from atmospheric, urban/suburban, wastewater, and agricultural sources and estimated thepollutant load reductions needed to improve dissolved oxygen in the Delaware River from the current3.5 mg/L to a future, more protective standard; (2) estimated the costs of nitrogen load reductions toimprove the dissolved oxygen levels in the tidal Delaware River for various best management practicescenarios; and (3) constructed marginal abatement cost curves to define the annual least costs to raisethe dissolved oxygen levels to more stringent fishable criteria.Nitrogen Loads: We estimated annual nitrogen loads in the Delaware Basin in Delaware,New Jersey, New York, and Pennsylvania using the USGS SPAtially Referenced Regressions onWatershed (SPARROW) model [40]. The SPARROW model has been calibrated by the USGS to estimatenitrogen loads for the base year 2002 from point sources (wastewater discharges) and nonpoint sources(atmospheric deposition, agriculture fertilizer/manure, and urban/suburban land) and accounts forwatershed characteristics such as precipitation, temperature, soil permeability, stream density, flow rate,velocity, and lake/reservoir hydraulics [41]. The USGS SPARROW model simulates nitrogen removalbased on hydrological processes such as denitrification, particulate settling, and water velocity [42].SPARROW is a nonlinear least squares regression model where the mean annual N load, as thedependent variable, is weighted by land-to-water movement, instream transport, and assimilationof nitrogen as the explanatory variable (Table 3). Since the USGS SPARROW model calibrates thenitrogen load estimates with EPA STORET water quality monitoring data, the model is well correlatedas coefficients of determination (r2 ) are 0.83 for yield and 0.97 for load, which explains 83% to 97% ofthe variance between the predictive model and observed water quality data.Table 3. Mid-Atlantic SPAtially Referenced Regressions on Watershed (SPARROW) model coefficients [40].ParameterNitrogen SourcesDeveloped land (km2 )Wastewater discharge (kg/year)Fertilizer and fixation from agriculture in corn, soybeans, alfalfa (kg/year)Fertilizer to agriculture in other crops (kg/year)Manure from livestock (kg/year)Land to Water DeliveryMean annual temperatureAverage overland flow distance to stream (km)ln ratio of nitrate to inorganic N wet depositionAquatic DecayTime of travel in stream reach where mean discharge 2.83 m3 /s (days)StatisticsRoot Mean Square Error (RSME)r2 loadr2 yieldCoefficient UnitModel Coefficientkg/km2 /year14221.160.3100.1860.090ln deg Ckm 1 0.864 0.1902.56per day0.2240.350.970.83
Water 2018, 10, 957 of 21Water 2018, 10, x FOR PEER REVIEW7 of 20Nitrogen Load Reduction Costs: We estimated the N load reductions needed to improveNitrogenWeestimatedoxygenthe N loadreductionsto improvewaterwater qualityto Loadmeet Reductiona future 5.0Costs:mg/Ldissolvedstandardin theneededDelawareRiver tandardintheDelawareRiverbetweenPhiladelphia and Wilmington. We examined the EPA Water Quality Analysis Simulation ProgramPhiladelphiaand Wilmington.We examinedthe EPA WaterQualityAnalysis SimulationProgram(WASP),USGS HydrologicalSimulationProgram-Fortran(HSPF),and rshedFunction (GWLF) to estimate Total Maximum Daily Load (TMDL) pollutant load reductions in theLoadingFunction(GWLF)to estimateTotal MaximumLoad(TMDL) pollutant load reductionslowerDelawareBasin[43]. secondary”treatment isin the lower Delaware Basin [43]. These hydrodynamic models suggest “better-than-secondary”needed to meet a more stringent dissolved oxygen water quality standard of 5 mg/L in the Delawaretreatment is needed to meet a more stringent dissolved oxygen water quality standard of 5 mg/L in theRiver at Philadelphia.Delaware River at Philadelphia.We reviewed a survey of 15 TMDL models by Scatena et al. [44] in the lower Delaware River thatWe reviewed a survey of 15 TMDL models by Scatena et al. [44] in the lower Delaware Riversuggests that achieving a dissolved oxygen target of 5.0 mg/L would require a 32% (median) reductionthat suggests that achieving a dissolved oxygen target of 5.0 mg/L would require a 32% (median)in nitrogento waterbodies,withina rangefrom20% from(25th 20%percentile)to 48% (75thpercentile)reductionloadingin nitrogenloadingto waterbodies,withina range(25th percentile)to e) reduction (Figure 5). Similarly, the Brandywine-Christina watershed TMDL modela doxygenwaterqualitycriterionestimated that a 38% reduction in nitrogen loads is needed to meet a dissolved oxygen water quality of5 mg/Lin thecontributes8% of the N8%loadto theDelawareEstuary [45].criterionof 5watershedmg/L in thethatwatershedthat contributesof theN loadto the DelawareEstuary [45].Nitrogen Reduction from TMDLsLower Delaware River100% N Reduction8060402001Figure 5. Nitrogen load reductions from Total Maximum Daily Load (TMDL) models for the lowerFigure 5. Nitrogen load reductions from Total Maximum Daily Load (TMDL) models for the lowerDelaware River [44].Delaware River [44].Best Management Practice (BMP) Installation Costs: We derived the unit costs of N loadBest ManagementPractice(BMP)InstallationCosts:We derivedunit costsof BMPsN loadreductions( /lb N reduced)for pointsourcewastewatertreatmentBMPs andthenonpointsourcereductions( /lb N reduced)for (vehiclepoint sourcewastewatertreatmentBMPsand nonpointsource BMPssuch as atmosphericcontrolsexhaustand industrialplantscrubbers),urban stormwatersuchas atmosphericcontrols (vehicleexhaustand industrialplanturbanstormwaterretrofitting,stream restoration,wetlands,and agriculturalpracticessuchscrubbers),as no till, rops,buffers, and animal waste management (Table 4).forest buffers, and animal waste management (Table 4).Table 4. Nitrogen reduction best management practices.Table 4. Nitrogen reduction best management practices.Nitrogen SourceBest Management Practice (BMP)Wastewater Treatment PlantNutrient Reduction TechnologyNitrogen SourceBest Management Practice (BMP)Motor vehicle exhaust antNutrient ReductionTechnologyPower/industrialplant scrubbersMotorvehicleexhaustAg Nutrient Management controlsPlansAtmospheric DepositionPower/industrial plant scrubbersConservation TillageAg NutrientManagement PlansCover CropsConservation TillageAgricultural ConservationDiversionsCover CropsForestDiversionsBuffersAgricultural ConservationForestBuffersGrassBuffersGrass BuffersTerracesTerracesWet Detention PondWet Detention PondGrass SwaleGrass banStormwaterUrban/Suburban cementStormwaterWetlandStormwaterWetlandVegetated Filter StripVegetated Filter Strip
Water 2018, 10, x FOR PEER REVIEW8 of 20Water 2018, 10, 958 of 21We calculated the costs to reduce nitrogen loads by 20% (25th percentile), by 32% (median), andby 48% (75th percentile) to meet a more stringent DRBC dissolved oxygen standard by multiplyingWe calculatedcoststo reduceby 20%(in(25thpercentile),by 32%(median),NOXandN loadreduction therates(kg/year)by nitrogenthe unit loadscost ( /kg)2010dollars) ction, wastewater treatment, agriculture conservation, and urban/suburban BMPs. Theloadreduction(kg/year)by Loadthe unitcost ( /kg)(infor2010for ns of 32% (median) within a range of 20% (25th percentile) and 48% (75th percentile). UsingMaximumDailytransferLoad (TMDL)modelsfor the DelawareRiver [46–49]requiredandnitrogenload nitrogenreductionsofbenefit (value)principles,we reviewedthe byof 20%watersheds(25th percentile)48%(75th percentile).benefit (value)reductioncosts( /kg)a from(suchandas theChesapeakeBay) toUsingthe tershed since the adjacent watersheds share similar climate, soils, topography, physiography,costsand( theDelawareRiverwatershedsincehydrogeology.the adjacentwatershedssharesimilar c
While just the 33rd largest river in the United States, the Delaware River is the longest undammed river east of the Mississippi, extending 390 mi (628 km) from the 3000 ft (970 m) high Catskill Mountains in New York State to the mouth of the Delaware Bay at Cape May, New Jersey. The river
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