From model outputs to conservation action: Prioritizing locations for implementing agricultural best management practices in a Midwestern watershed

Transcription

1 doi: /jswc From model outputs to conservtion ction: Prioritizing loctions for implementing griculturl best mngement prctices in Midwestern wtershed J.T. Legge, P.J. Dorn, M.E. Herbert, J. Asher, G. O Neil, S. Mysorekr, S. Sow, nd K.R. Hll Abstrct: Mny ecologiclly significnt Midwestern rivers re hevily impcted by griculture yet retin high vlue for conservtion of biodiversity. To ddress these concerns, wtershed mngers promote conservtion prctices (e.g., use of cover crops). Yet tking ction to promote implementtion of these prctices in cost-effective mnner cross wtershed is difficult becuse we rrely know where prctices will be most effective, or how much of benefit will ccrue s the result of implementtion of given prctice. To improve trgeting of conservtion prctice implementtion in loctions most beneficil to biodiversity, we propose using flexible pproch ssessing fields cross wtershed for contributions towrds ecologicl outcomes. We focused on Michign s Pw Pw River Wtershed, where key concerns for biodiversity include reduced infiltrtion nd groundwter rechrge tht led to pronounced low nd high flow periods, nd reduced wter qulity due to high sediment lods. We used outputs from severl existing models to identify nd prioritize the griculturl fields where conservtion prctices will hve the gretest reduction in threts to biodiversity, including estimtes of the input to groundwter nd reduction in sedimenttion. We tested the usefulness of our pproch using four scenrios for implementtion of six prctices tht vry in terms of the concentrtion of the prctices in res recommended by the models. Estimtes of groundwter rechrge under these scenrios were compred to rechrge under simulted, historic plcement scenrios bsed on USDA Nturl Resources Conservtion Service (NRCS) dt for pplied conservtion prctices in the sme wtershed. Collectively cross the six prctices, the prioritized scenrios provided n increse in groundwter rechrge of between 23% nd 36% over the historic scenrio. Results for sediment reduction were more vrible, but prioritized scenrios suggested doubling of benefit cn be obtined by focusing on griculturl lnds predicted to contribute the highest sediment volumes. To mximize the benefits of ggregting prctices, we identified subbsins of the wtershed for direct outrech to lndowners bsed on rnking of potentil, cumultive downstrem conservtion benefits nd on opportunity fctors. As result of this process, prioritized res nd estimtes of groundwter rechrge re now informing implementtion of conservtion prctices in the Pw Pw River Wtershed, n pproch pplicble cross the region. Key words: conservtion prctices groundwter rechrge modeling quntifiction of benefits sedimenttion The outcomes of griculturl conservtion prctices, while typiclly evluted by cres implemented or similr ppliction prmeters, cn be more dequtely judged using quntifiction of ecologicl outcomes to provide more meningful indiction of vlue nd n incentive for efficient use of funding. Like most conservtion chllenges where resources re very limited reltive to the scle of impcts, effectively protecting rivers nd other nturl hbitts in griculturl lndscpes requires tht we prioritize our investments. Mny reserchers hve developed tools nd models to help define wht spects of the ecosystem re t risk (Sow et l. 2007; Esselmn et l. 2011) nd wht griculturl best mngement prctices cn help reduce impcts (Mishr et l. 2007; Diebel et l. 2009). However, delivering mesurble benefits to sensitive systems requires tht we connect theoreticl models to relevnt conservtion outcomes nd improve our understnding of how to mesure, nd produce, conservtion success. In the context of implementing griculturl conservtion prctices, the gol of incresing benefits to ecologicl systems is constrined by mismtch in how success is mesured, in tht efforts re typiclly evluted by cres of prctice implementtion. Here we describe demonstrtion of our efforts to shift mesurements towrd quntifiction of ecologicl outcomes, which we suggest provides more meningful indiction of vlue nd n incentive for efficient use of funding. The USDA Nturl Resources Conservtion Service (NRCS), in prtnership with locl soil nd wter conservtion districts, hs been ssisting frmers nd rnchers with voluntry implementtion of griculturl conservtion prctices to ddress soil, wter, nd relted nturl resource concerns for mny decdes. Vrious conservtion progrms uthorized through federl (Frm Bill) policy provide finncil ssistnce to producers to implement these conservtion prctices. Supported by NRCS technicl stndrds, conservtion prctices hve been widely used s strtegy for reducing nonpoint source pollution from frmlnds into surfce wterwys. Some conservtion prctices, such s conservtion tillge, lso improve groundwter infiltrtion, which cn reduce the excessive flshiness frequently found in wtersheds dominted by griculture (Schilling nd Libr 2003; Swinton et l. 2007; Tomer et l. 2005). Mximizing these benefits is common gol for wtershed mngers. Unfortuntely, conservtion prctices frequently do not ttin the desired wter- John T. Legge is conservtion project director, Ptrick J. Dorn is director of conservtion, nd Mtthew E. Herbert is n qutic ecologist with The Nture Conservncy, Lnsing, Michign. Jeremih Asher is geogrphic informtion system (GIS) project mnger, nd Glenn O Neill is GIS specilist with the Institute for Wter Reserch, Michign Stte University, Est Lnsing, Michign. Sgr Mysorekr is GIS mnger, Scott Sow is director of science, nd Kim R. Hll is Gret Lkes climte chnge ecologist with The Nture Conservncy, Lnsing, Michign. 22 JAN/FEB 2013 VOL. 68, NO. 1

2 shed-scle wter qulity benefits (Tomer nd Locke 2011). When combined with n incresing risk tht public funding for conservtion prctices my be reduced, it is criticl tht we find wys to increse the benefits ttined from the prctices implemented. Since the mgnitude of benefits tht ccrue from conservtion prctices vries with the soils, distnce to wter body, topogrphy, nd crop (Qiu 2003; Gitu et l. 2005), mny modeling efforts hve developed trgeting or optimiztion systems to identify the most cost-effective set of loctions for implementing conservtion prctices in given wtershed (Richrdson nd Gtti 1999; Veith et l. 2004; Mishr et l. 2007; Schilling nd Wolter 2009). However, optimiztion systems re often focused on single optiml solution of preferred loctions, mking the outcome insufficiently flexible for prcticl pplictions where ctul implementtion is only possible with willing lndowners. Another shortcoming of most trgeting efforts is tht they re focused on individul outcomes (e.g., sediment). These re importnt first itertions, but ultimtely conservtion prctices re implemented for multiple objectives. Quntifiction of ecologicl benefits tht would ccrue from specific conservtion prctices on individul prcels would provide more flexible, relistic, nd useful tool, especilly to enble scling incentive pyments to mtch the benefits from specific producers ctions (Wünscher et l. 2008). Quntifiction could lso be used to prioritize lnds for receiving finncil support for implementing prctices, incresing the efficiency in reching wtershed improvement gols. Through quntifiction of ecologicl benefits, we cn begin to evlute whether we cn effectively prioritize for multiple benefits nd still provide significnt progress towrd ech specific type of benefit. While using tools to optimize benefits to fctors such s wter qulity, it is criticl tht we recognize tht these benefits will be provided cross complex lndscpe. Some res provide greter quntifible conservtion benefits thn others, nd conservtion prctice plcement should reflect not only wter qulity benefits but lso the overrching conservtion outcomes. For exmple, improving wter qulity upstrem from high qulity ecosystems, highly vlued resources (e.g., fisheries), or wter bodies used s drinking wter re importnt societl benefits. Priority res for mximizing wter qulity benefits should be juxtposed with these types of high-vlue conservtion trgets. Southwest Michign s Pw Pw River Wtershed hs been identified s importnt for biodiversity conservtion in the Gret Lkes Bsin (Nture Conservncy 2001). The river is significnt for its reltively intct, forested floodplin; diverse hedwter communities with lrge pririe fen nd swmp systems, buffered by remnnt ok svnns; nd the qulity of the freshwter community in the min stem of the Pw Pw River nd in the Est Brnch, hedwter tributry (Nture Conservncy 2001). The wtershed covers pproximtely 115,560 h (285,557 c) with its outlet locted t N, W nd totl length of pproximtely 233 km (145 miles), including mjor tributries. According to the 2001 Ntionl Lnd Cover Dtset (NLCD), row crop griculture covered roughly 39% of the wtershed (Homer et l. 2007). This lnd use pttern hs contributed to sedimenttion nd chnges in the hydrologic regime. The upper nd middle sections of the Pw Pw Wtershed re dominted by sndy/lomy soil types in hydrologic soil group (HSG) A, which provide the river with moderte to high groundwter inputs. In the lower prts of the wtershed, sndy clylom soils (HSG C soils) predominte, with lower infiltrtion rte. Slopes re modest through much of the wtershed. Improving groundwter rechrge ws identified s prticulrly importnt fctor for mintining the historic hydrologic regime of the Pw Pw due to the nturlly high groundwter inputs to the river system (Michign Deprtment of Environmentl Qulity 2005) nd trends in stremflow tht indicte incresing runoff nd decresing groundwter contributions in recent yers (Nture Conservncy 2008). Sedimenttion ws lso identified s key thret to the ecology of the river (Nture Conservncy 2008). Our objective ws to prioritize griculturl lnds in the Pw Pw Wtershed to determine where to focus trgeted outrech tht mximizes ecologicl outcomes from the implementtion of USDA conservtion prctices. Our intent ws to develop flexible system tht would highlight differences in the conservtion benefit potentil cross the griculturl lndscpe, llowing trgeted recruitment of high-benefit lndowners tht could include dded finncil incentives. We utilized well-estblished hydrologicl models to identify the loctions likely to return the gretest environmentl benefits s mesured by groundwter rechrge nd sediment retention if conservtion prctices were implemented. We lso identified priority subwtersheds bsed not only upon the concentrtion of field-scle benefits, but lso with considertion to connectivity to the min stem of the river, position in the wtershed, nd conservtion opportunity ll which re importnt vribles guiding overll effectiveness of conservtion efforts. This is mong the first studies to (1) prioritize loctions for griculturl conservtion prctices for multiple ecologicl benefits, t both the field scle for implementtion nd the subwtershed scle for conservtion plnning nd outrech, nd (2) quntify the differences in ecologicl benefits mong vrious trgeting pproches. Mterils nd Methods Model nd Decision Tool Development. We first used set of well-estblished hydrologicl models to produce informtion on prmeters tht would help us identify the loctions likely to return the gretest environmentl benefits s mesured by groundwter rechrge nd sediment retention if conservtion prctices were implemented. These prmeters included (1) res t gretest risk of erosion contributing to strem sedimenttion, bsed on High Impct Trget (HIT) modeling (Ouyng et l. 2005); (2) potentil for improving infiltrtion (nd ultimtely contributions to groundwter) by implementing conservtion prctices, using Soil nd Wter Assessment Tool (SWAT) simultion modeling; nd (3) likelihood of groundwter withdrwl to dversely ffect fish communities, using Michign s Wter Withdrwl Assessment Tool (Michign Deprtment of Environmentl Qulity 2009) (figure 1). The outputs of three models were generted nd merged t the scle of 900 m 2 (9,688 ft 2 ) grid cells. The resulting vlues cn be combined cross the re of n individul frmer s fields (i.e., the units of lnd tht frmer mnges) to prioritize res for specific conservtion prctices (those beneficil for incresing groundwter rechrge nd reducing sedimenttion) cross the Pw Pw River Wtershed. Our nlysis focused on row crop frmlnd becuse there re mny conservtion prctice options for improving rechrge nd reducing sedimenttion. While orchrds re lso prominent in the wtershed, their perennil cropping system produces proportionlly JAN/FEB 2013 VOL. 68, NO. 1 23

3 Figure 1 Conceptul model for identifiction of the most efficient loctions for implementtion of conservtion prctices. We combined models for three fctors: susceptibility to dditionl groundwter withdrwl using Michign s Wter Withdrwl Assessment Tool, groundwter rechrge potentil using the Soil nd Wter Assessment tool, nd res t risk of erosion contributing to strem sedimenttion using High Impct Trgeting. The outputs were combined to produce field-scle priorities. Second, we fctored in locl conditions to identify priority subwtersheds for implementtion using plcement within the wtershed, conservtion opportunity, nd min stem connectivity. Groundwter rechrge chnge potentil Groundwter withdrwl susceptibility High risk erosion res fewer impcts to hydrology nd sedimenttion, so conservtion prctices produce fewer benefits. Also, fewer conservtion prctices for orchrds re vilble for implementtion nd modeling. The HIT model ws used for estimting sediment delivery. Avilble for the United Sttes portion of the Gret Lkes Bsin (O Neil et l. 2009), HIT is product of two underlying models: the Revised Universl Soil Loss Eqution or RUSLE (Renrd et l. 1997), which estimtes nnul volume of eroded soil, nd the Sptilly Explicit Delivery Model or SEDMOD (Frser 1999), which estimtes the percentge of soil from ny given re tht enters strem system s sediment. We rn ech model within geogrphic informtion system (GIS) rster environment, t 900 m 2 (9,688 ft 2 ) cell resolution. Outputs from the RUSLE model were clculted bsed on slope-length reltionships derived from United Sttes Geologicl Survey (USGS) 30 m (98 ft) resolution digitl elevtion models (DEMs), soil erodibility (K-fctor) from the USDA Soil Survey Geogrphic (SSURGO) dtbse (USDA NRCS 1995), nd nnul rinfll intensity (R-fctor) from the Prmeter-elevtion Regressions on Independent Slopes Model group t Oregon Stte University (PRISM Climte Group 2002). These dt were combined with version of the 2001 NLCD (Homer et l. 2007) tht ws integrted with tillge prctice nd crop rottions inferred from Conservtion Technology Informtion Loction within wtershed Field-scle priorities Connectivity to minstem Conservtion opportunity Subwtershedscle priorities Center Crop Mngement Surveys (CTIC 2000, 2002, 2004) for the study re. Our SEDMOD runs utilized the sme DEMs nd the USGS High Resolution Ntionl Hydrogrphy Dtset to simulte surfce wter flow nd the strem network of the Pw Pw River Wtershed. These were combined with cly content informtion from SSURGO nd surfce roughness derived from the NLCD to chrcterize the pth nd trnsport of sediments to the strem network. Through combining the RUSLE nd SEDMOD outputs, the HIT model identifies those res t gretest risk of producing eroding sediment tht will rech the river or its tributries. Model efficiency mesures of RUSLE-estimted verge nnul soil loss compred to observed soil loss hve rnged between 0.7 nd 0.8 (Risse et l. 1993; Rpp 1994; Tiwri et l. 2000). Unlike RUSLE, the SEDMOD component of HIT hs not hd extensive testing. The most rigorous vlidtion of the ccurcy of HIT s output t subfield level resolution (nd therefore the most rigorous vlidtion of SEDMOD) ws ssessed in three Michign 8-digit hydrologic unit code wtersheds with similr geology, soils, nd lndform to tht of the Pw Pw. Tht nlysis determined tht HIT is roughly 70% ccurte in identifying sedimenttion risk (O Neil 2010). The vlidtion did not mesure ctul sedimenttion volume; those vlues depend on the ccurcy of RUSLE itself, which is lredy well-estblished. The ssigned vlues of nnul erosion reching strems from the 900 m 2 units of griculturl lnd cross the wtershed vried from more thn 1.8 t h 1 y 1 (0.8 tn c 1 yr 1 ) (7% of griculturl lnd in the wtershed), to 0.89 to 1.80 t h 1 y 1 (0.4 to 0.8 tn c 1 yr 1 ) (11% of griculturl lnd), to 0.44 to 0.89 t h 1 y 1 (0.2 to 0.4 tn c 1 yr 1 ) (14% of griculturl lnd) (figure 2). Remining cells in griculturl res contributed less thn 0.44 t h 1 y 1 (0.2 tn c 1 yr 1 ) of sediment. It is importnt to point out tht these estimtes re likely below the ctul erosion nd sediment loding occurring in the Pw Pw becuse RUSLE only estimtes nnul sheet erosion nd does not quntify erosion from lrge gullies, strem bnks, or wind. However, the reltivized estimtes of erosion nd sediment loding provided by HIT re still very useful for prioritizing conservtion ctions t the wtershed scle. Infiltrtion nd groundwter rechrge were modeled with SWAT (Neitsch et l. 2005). The SWAT model hs been widely used to ssess infiltrtion on wtershed scle (Gssmn et l. 2005). The SWAT model ws used to estimte the hydrologic wter blnce in the Pw Pw River Wtershed under current lnd cover nd then to estimte groundwter rechrge for brod soil types under different lnd mngement prctices. The wtershed ws divided into subbsins nd then subdivided into hydrologic response units representing different combintions of lnd use/lnd cover/mngement, soil type, nd wether dt. For ech unit, wter budget ws clculted including dily surfce runoff nd pek runoff rte. Reltionships between soil type, lnd cover, nd wter infiltrtion cross modeling units were identified nd used to crete n estimte of infiltrtion nd groundwter rechrge under different soil types (i.e., HSGs) nd with different potentil lnd uses nd types of griculturl mngement. Soil mps were creted to reflect differences in rechrge benefits mong soil types with chnges in lnd cover or griculturl mngement. The wter blnce model within SWAT ws developed bsed on the work of two previous studies within the Klmzoo River Wtershed (Sffermn et l. 2008). The SWAT model ws clibrted on subbsin level within the Klmzoo River Wtershed using USGS guge dt from seven guging sttions, including the Pw Pw River guge (USGS guge # ), to clibrte stremflow between guging sttions. 24 JAN/FEB 2013 VOL. 68, NO. 1

4 Figure 2 Estimted sediment loding in the Pw Pw River Wtershed, Michign, bsed on High Impct Trgeting. Legend Pw Pw River Sediment (tn c 1 yr 1 ) < to to 0.8 > mi Tble 1 Exmples of chnge in groundwter rechrge in liters per yer per cre of griculturl lnd from selected conservtion prctices, s modeled by SWAT. Conventionl to Conventionl to reduced tillge Conventionl reduced tillge (such s mulch till) Conventionl to no-till plus (such s mulch till) plus cover crop to no-till cover crop Soil type (gl yr 1 c 1 ) (gl yr 1 c 1 ) (gl yr 1 c 1 ) (gl yr 1 c 1 ) A-D soil 29,900 65,200 65,200 31,000 A soil 32,000 17,100 71,600 55,600 B soil 40,600 20, ,200 42,800 C soil 42,800 11, ,900 68,400 Observed flow from ech guging sttion ws seprted between surfce runoff nd bse flow using USGS Hydrogrph Seprtion Progrm softwre. The model ws clibrted to observed surfce nd bse flow by primrily djusting the curve number (CN2), soil evportion compenstion fctor (ESCO), lph bseflow fctor, nd groundwter rechrge percoltion frction (RCHRG_ DP). Independent greement ws found when the SWAT model bseflow results were compred with the USGS 1 km (0.62 mi) estimted groundwter rechrge mp (Neff et l. 2005). Lnd mngement prctices were primrily chnged with the curve number prmeter bsed on literture vlues. Within the SWAT modeling component, severl dtsets were required to model the hydrology of the wtershed. The USDA Stte Soil Geogrphic dtbse (USDA NRCS 2012c) ws used to model the overll hydrology of the wtershed under current lnd use. The SSURGO dtbse (USDA NRCS 1995) identified individul HSGs tht lie within the wtershed, nd these soils were used to model specific lnd mngement prctices. For current lnd use dt, the Michign Center for Geogrphic Informtion supplied the 2001 Integrted Forest Monitoring, Assessment, nd Prescription Lower Peninsul Lnd Cover dtset developed by the Michign Deprtment of Nturl Resources (MDNR). We converted lnd use clsses identified by the MDNR dt to equivlent SWAT model lnd use clsses. Wether dt for dily rinfll, mximum nd minimum temperture, nd solr rdition were obtined through the Michign Climte Office for the longterm Ntionl Wether Service sttion t Bloomingdle, Michign, just north of the Pw Pw River Wtershed. These wether dt were verged cross the period of 1971 to The DEM used to delinete the Pw Pw River Wtershed within the SWAT model ws from sttewide coverge obtined from the Michign Center for Geogrphic Informtion. The DEM hd sptil resolution of 30 m (98 ft) nd ws projected in the Michign Georef Projection. As prt of the process of estimting groundwter rechrge nd infiltrtion from SWAT, dt were verged within the four min HSGs in the wtershed. Rnging from the sndiest soils with gretest percoltion to the most hydric soils, these HSGs re lbeled A-D, A, B, nd C. The outputs from this component of our prioritiztion indicte tht groundwter rechrge benefits from conservtion prctices vried with soil type. Soils in HSG C hve the lowest infiltrtion rtes nd respond with the highest groundwter rechrge increses under reduced tillge nd no-till. But when cover crops re dded to tillge prctices, HSG A soils with high infiltrtion rtes produce the gretest rechrge increses (tble 1). The complexity of the interctions between soil type nd prctices cn hinder the effective use of such informtion by locl prctitioners. So, to fcilitte use of these dt by locl prctitioners, the SWAT dt ws plced into n online groundwter rechrge clcultor (Asher et l. 2010). The SWAT modeling results were first used to crete look-up tble compring the difference in infiltrtion between potentil lnd uses nd mngement regimes cross soil types for ll griculturl lnds in the Pw Pw River Wtershed. The look-up tble ws then linked with soil dt through n online mp interfce, llowing users to drw polygon for prcel of lnd nd identify the chnge in lnd use (e.g., from conventionl tillge griculture to reduced tillge griculture). This clcultor llows the user to estimte chnges in groundwter infiltrtion in gllons per cre, on the fly, from potentil chnges in lnd mngement. Finlly, the third set of model inputs tht informed our prioritiztion cme from the WWAT model, which ws used for ssessing sensitivity to groundwter withdrwl. Developed by the Institute for Wter Reserch t Michign Stte University, MDNR, USGS, nd Michign Deprtment of Environmentl Qulity, WWAT is tool tht estimtes the mount of flow of river or strem tht could be reduced (e.g., through JAN/FEB 2013 VOL. 68, NO. 1 25

5 Figure 3 Risk of subbsins of the Pw Pw River Wtershed, Michign, to dditionl groundwter withdrwls bsed on the stte s Wter Withdrwl Assessment Tool. Legend Avilble groundwter before dverse resource impct (gl min -1 ) 24 to 150 (highest risk) 150 to to 1,580 1,580 to 3,700 3,700 to 9,895 (Lowest river) Pw Pw River mi groundwter pumping) before the species composition nd bundnce of fish in the river would be dversely impcted (Reeves et l. 2009). The tool provides wter vilbility mp developed from estimted index flow for the lowest summer flow month vi nlysis of long-term stremflow guging sttions nd regression modeling from unguged strem sites (Hmilton et l. 2008), nd fish response curves relted to ctchment re, bseflow yield, nd July men temperture. The underlying model uses hbitt suitbility informtion from Michign for over 40 fish species to predict ssemblge structure nd chrcteristic ssemblges in river segments under rnge of bse flow reductions. River segments sttewide were clssified into 11 types relted to ctchment size nd July river temperture, nd fish ssemblges were predicted for ech combintion. Model runs developed for individul fish species t representtive segments of the river types were used to develop curves describing the response of ech fish ssemblge to flow reduction. The resulting WWAT model provides frmework for evluting impcts of flow withdrwls on fish communities cross Michign (Zorn et l. 2008). The model ws used to identify those subbsins in which diversion of 568 L min 1 (150 gl min 1 ) of bseflow (either vi groundwter pumping or surfce wter withdrwl) would be likely to result in the degrdtion of fish community species composition. Avilble bseflow t or below 568 L min 1 is reltively smll nd could be exceeded with the instlltion of one typicl high cpcity wter withdrwl. In nlyzing sensitivity to groundwter withdrwl, the WWAT model identified eight subbsins tht re t gretest risk, in which 91 to 568 L min 1 (24 to 150 gl min 1 ) of bseflow is vilble for pumping before potentilly cusing n dverse impct (figure 3). Seven of these subbsins re quite smll, representing only 3.4% of the griculturl lnd in the Pw Pw Wtershed. The eighth t-risk subbsin, Mill Creek, is one of the lrger (4,500 h [11,100 c]) nd more significnt griculturl portions of the wtershed, with 9.7% of the wtershed s griculturl lnd. Remining subbsins re currently t reltively low risk from dditionl groundwter pumping. Prioritiztion Process nd Approch: Field-Scle Prioritiztion. To identify priority loctions where conservtion prctice implementtion could optimize groundwter rechrge, minimize sediment loding, nd buffer ginst groundwter withdrwl impcts, we combined dt from the three models (HIT, SWAT, nd WWAT) nd mpped the resulting clcultion, termed priority vlue, including only lnds in the wtershed with ctive row crop griculture. We ssigned the highest vlue to griculturl lnds where HIT estimted sediment loding s high, where the WWAT indicted low mount of vilble groundwter s bseflow to strems, nd on soils tht would provide the highest groundwter rechrge modeled in SWAT. The three input lyers were reclssified into numeric clsses from 1 to 4 t nturl breks, with 4 considered to hve the highest score. Sedimenttion risk ws ssigned the highest weight becuse the HIT modeling provides the most site-specific informtion. We gve the lowest weighting to groundwter vilbility (modeled by WWAT) becuse Michign lw lredy requires use of this model in groundwter permitting. Soil Wter Assessment Tool modeling demonstrted tht HSG plyed strong influence on the benefits of tillge prctices, so reltively moist HSG C soils were considered nd mpped seprtely from drier A soils. This weighting scheme ws derived bsed on locl knowledge of the wtershed nd desired ecologicl outcomes. Our nlysis of the prioritiztion outcomes ws designed to test the effectiveness of our pproch. The following clcultions were used for C soils: Priority vlue = (Sedimenttion-risk priority 0.8) + (Groundwter vilbility priority 0.2) (Soil priority [A = 0, B = 0.5, C = 1, D = 0]) (Lnd cover priority [Row crop lnds = 1, All other lnds = 0]). (1) The following clcultions were used for A soils: Priority vlue = (Sedimenttion-risk priority 0.8) + (Groundwter vilbility priority 0.2) (Soil priority [A = 1, B = 0.5, C = 0, D = 0]) (Lnd cover priority [Row crop lnds = 1, All other lnds = 0]). (2) The rnge in priority vlue, mpped t the 900 m 2 (9,688 ft 2 ) scle (mtching the HIT modeling), differentites mong units of lnd by the extent to which they re t risk for producing sediment, their potentil for providing dditionl groundwter rechrge under conservtion prctices, nd the existing level of stress of groundwter resources. With higher priority vlue, we expect tht conservtion prctices on tht lnd will provide greter benefits in terms of reduced sedimenttion nd incresed groundwter rechrge. Subwtershed-Scle Prioritiztion. In ddition to the field-scle prioritiztion, we lso wnted to prioritize t the subwtershed 26 JAN/FEB 2013 VOL. 68, NO. 1

6 scle so tht we could focus outrech within subsections of the wtershed, rther thn t high-rnking fields cross the entire geogrphic re. Two units of lnd my hve the sme priority vlue, but one my produce greter benefits for the overll wtershed bsed on its plcement in the wtershed (e.g., upstrem res will hve greter impct thn those further downstrem). Concentrting lndowner outrech nd resulting conservtion prctices in smller prt of the wtershed lso llows us to concentrte BMPs, which should increse our bility to detect improvements. This concentrtion of effort will lso improve the efficiency of time spent working with lndowners. In effect, we re dding n dditionl set of subbsin-scle fctors to the modeling results, with the gol of converting these results to more ctionble subset of prioritized lnds tht cn be used to inform focused outrech efforts nd subsequent implementtion of conservtion prctices nd produce the gretest impcts on conservtion trgets. We scored the subbsins bsed on the following four criteri: () Wtershed position: Improvements in wter qulity nd quntity within wtershed will provide the most benefits to prticulr river system if they re implemented nerer to the hedwters of the wtershed. Scoring: 1 to 4 points, with 1 point for the subbsins of the first third of the min stem towrds the outlet, 2 points for the subbsins of the middle third of the min stem, 3 points for the subbsins long the upper third of the min stem, nd 4 points for the hedwters subbsins. (b) Connectivity to the min stem: Reduction in sedimenttion nd hydrologic restortion due to incresed groundwter rechrge will hve less downstrem benefit in subbsins tht re prtilly or wholly cut off from the min stem by reservoirs nd/or dms. Scoring: 2 points for subbsins cut off by reservoirs nd 4 points for other subbsins. (c) Concentrtion of priority loctions: Although ll subbsins contin res tht were identified s high in priority vlue through the modeling processes, high vlue loctions re more concentrted in some res. Concentrtion ws clculted bsed on the proportion of subbsin s re with priority vlue of 3 or more. Scoring: 1 to 4 points bsed on nturl breks in the proportion of impct in subbsin, with subbsins hving the gretest concentrtion of high priority vlue res receiving 4 points. (d) Opportunity: The Vn Buren Conservtion District hs long history of working with Pw Pw Wtershed frmers to encourge implementtion of conservtion prctices. Vn Buren Conservtion District stff informlly evluted the results of the nlysis nd identified res of significnt opportunity bsed on three fctors: (i) perceived interest of frmers not lredy enrolled in conservtion progrms, (ii) complementrity with conservtion outrech efforts by the Vn Buren Drin Commissioner, nd (iii) potentil for lrgest impct bsed on lnd ownership pttern nd existing prctices. Scoring: 4 points if identified s hving opportunity for fctors i, ii, nd iii; 3 points if identified s hving opportunity for 2 of the 3 fctors; 2 points if identified s hving opportunity for 1 of the 3 fctors; nd 1 point if not identified s hving ny opportunity fctors. The scores for the four criteri were summed for ech subbsin to develop n overll score tht would be used to guide outrech nd enrollment. Assessing Likely Efficiencies nd Benefits of Our Approch. Following our work developing the prioritiztion components, we exmined the level of increse in ecologicl benefits suggested by our modeling tools if we were to successfully implement conservtion prctices t the prioritized loctions in the Pw Pw River Wtershed. We compred estimtes of groundwter rechrge benefits nd sedimenttion rtes for three plcement scenrios: (1) historic loctions, (2) rndom loctions, nd (3) four sets of priority loctions. All scenrios were bsed upon the type, size, nd frequency of prctices implemented in the wtershed from 1999 to 2009 (herefter referred to s historic dt) (USDA NRCS 2010). Conservtion prctices were limited to those tht were pplicble to groundwter rechrge nd sedimenttion benefits nd tht were implemented in t lest 25 loctions during the historic conservtion prctice period. These prctices included: (1) Conservtion Cover (perennil vegettive cover, NRCS Prctice Code #327); (2) Cover Crop (#340); (3) nd Tillge Mngement, Mulch Till (#345); (4) nd Tillge Mngement, No-Till/ Strip Till/Direct Seed (#329); (5) Mngement, Mulch Till (#329B); nd (6) Mngement, No-Till/Strip Till (#329A) (USDA NRCS 2012b). To represent prctices cross the wtershed, we used the NRCS historic dt on conservtion prctices which consist of point loction representing specific prctice type, with the re of the prctice included in the ccompnying dt. To convert these lists of point loctions to sptil representtion, we creted circulr buffers round ech point loction to crete polygons nd sized the buffer to mtch the ctul re of prctice implementtion. The resulting sptil dt represented our historic scenrio nd gve us wy of quntifying potentil benefits using sptil dt outputs from vrious steps in our prioritiztion process. To develop the rndom scenrio for plcement of prctices within griculturl lnds cross the wtershed, we lso used informtion from the historic prctice dt, but chnged their loctions. To do this, we generted set of rndom points for ech conservtion prctice using the rndom function from Geosptil Modeling Environment (Beyer 2012) tht ws equl to the number of loctions where ech prctice ws implemented historiclly. For exmple, if conservtion cover ws historiclly implemented t 158 loctions, then 158 rndom points were creted to represent the rndom scenrio for conservtion cover. Points for ech prctice were buffered to crete polygons mtching the verge size of tht prctice from the historic dtset. The rndom scenrio ws repeted three times so tht vrince could be clculted nd the scenrio could be sttisticlly compred. Similrly, to determine conservtion prctice loctions for our four priority scenrios, we built from the informtion contined in the historic griculturl plcement dt, but constrined the plcement of prctices to set of rndom loctions with concentrtions of high priority vlues. Given tht our prioritiztion ws t the level of 900 m 2 (9,688 ft 2 ) pixel, we ggregted the pixels to reflect the scle t which prctices would be pplied. To chieve this ggregtion, we pplied the neighborhood window function in ArcGIS to the priority vlue dtset to crete cler distinctions between res of high, medium, nd low priority vlue. For exmple, if high vlue cell ws surrounded by low nd medium vlue cells, it received JAN/FEB 2013 VOL. 68, NO. 1 27

7 men vlue bsed on its neighboring cells. This pproch incresed the likelihood tht high priority vlue cells bordered minly by other high priority vlue cells were selected. For neighborhood window we used circulr re round ech pixel with rdius set to produce n re equl to the verge size of tht prctice from the historic dtset. We produced four sets of prioritized res to include loctions for ll of the six prctices tken from within the top 5%, 10%, 20%, nd 30% of priority vlue res, s weighted by priority vlue of neighboring pixels. These scenrios were designted s the 5%, 10%, 20%, nd 30% priority scenrios, respectively. The process of selecting loctions for ech priority scenrio (5% up to 30%) ws repeted three times so tht vrince could be clculted, which llowed clcultions of benefits derived from ech scenrio to be sttisticlly compred with other scenrios. To clculte groundwter rechrge benefits, the sptil dt lyers representing historic, rndom, nd the four priority scenrio loctions for the six conservtion prctices were overlid with HSGs. For ech conservtion prctice type nd distribution scenrio (historic, rndom, nd multiple levels of priority re), groundwter rechrge rtes s determined for the wtershed by the SWAT modeling described bove were used to clculte the chnge in rechrge from conventionl tillge to ech conservtion prctice. Switchgrss (Pnicum virgtum) ws used s the lnd cover to clculte rechrge benefits for Conservtion Cover becuse this best represents the typicl lnd cover used for this prctice in the wtershed (J. Foster, personl communiction, Mrch 1, 2011). The groundwter rechrge rtes were clculted for ech soil type within ech prctice ppliction nd then combined for ech conservtion prctice type for ech scenrio. Portions of the wtershed contined null hydrologic soil vlues (e.g., wter or res outside of the wtershed). Approximtely 5% of buffers (polygons) contined smll percentge of re with these null vlues. In these cses, we clculted the sedimenttion or rechrge contribution by ssigning the no dt res to soil types in the sme proportion s ws found in the polygon. This llowed us to hold the totl re for ech prctice constnt cross ll scenrios. To clculte benefits from reduced sedimenttion, the verge sedimenttion susceptibility for ech scenrio ws clculted from HIT results using the zonl sttistics function from the GIS ppliction. The set of polygons for ech of the scenrios ws overlid onto the HIT sedimenttion lyer to clculte men sediment vlue for ech polygon. For ech conservtion prctice, we tested for differences mong the historic, rndom, nd the four priority scenrios using nlysis of vrince nd, with significnce, tested for specific differences mong scenrios using Tukey s honestly significnt difference test (Kirk 1968). Results nd Discussion Prioritiztion Process nd Approch: Field- Scle Prioritiztion. The prioritiztion generted through combining the vrious models resulted in two nlyses, one emphsizing the importnce of trgeting HSG A soils nd the other emphsizing HSG C soils due to their differentil influence on groundwter rechrge with different prctices. Ech 900 m 2 (9,688 ft 2 ) cell received priority vlue score rnging from 0 to 4, with 4 s the highest possible score indicting those plces where investments in conservtion prctices would yield the lrgest ecologicl outcomes (figure 4). For the HSG A, the high priority vlue indictes those res where combintion of conservtion tillge nd cover crop prctices would produce the gretest groundwter rechrge benefits. For the HSG C, conservtion tillge lone produces the gretest rechrge benefits. In both cses, the HIT modeling hd the gretest impct on the scoring becuse the HIT output is differentited t the 900 m 2 level. In contrst, SWAT produces the sme output cross soil type, nd WWAT produces the sme emphsis cross subbsin. Combined cross the HSGs, the prioritiztion identified 157 h (388 c) with the highest priority vlue of 4, or 0.35% of the griculturl lnd found in the Pw Pw Wtershed. There were 2,009 h (4,964 c) or 4.48% of griculturl lnd with priority vlue of 3; 4,017 h (9,926 c) or 8.96% with priority vlue 2; nd 21,628 h (5,3444 c) or 48.21% with priority vlue of 1. The remining row crop lnd of the wtershed, 38%, scored less thn 1. This distribution of priority vlue scores cross the wtershed shows the concentrtion of the highest vlues (priority vlue from 2 to 4) concentrted on smll prt of the griculturl lnd, only 13.79% of the totl croplnd. Subwtershed-Scle Prioritiztion. Scoring of subbsins differentited the 15 subbsins; with scores rnging from 7 to 14 points (figure 5). Three of the top four subbsins were selected for testing direct outrech to ccelerte implementtion of conservtion prctices, including Brndywine Creek (14 points), South Brnch (13 points), nd Mill Creek (12 points). Outrech nd implementtion begn s three-yer progrm in the three top subbsins in spring of 2010, through prtnership of the Vn Buren Conservtion District nd The Nture Conservncy with funding from the Coc-Col Foundtion. As of Jnury 2012, trgeted outrech hs brought n dditionl 853 h (2,108 c) of Pw Pw Wtershed crop lnd into conservtion prctices, of which 75% of these lnds come from the three top subbsins where outrech hs been focused. New conservtion prctices include cover crops, conservtion tillge, no-till, buffer strips, nd conservtion cover. Assessing Likely Efficiencies nd Benefits of Prioritizing Approch. The comprison between our four priority scenrios nd both historic nd rndom scenrios in the wtershed shows significnt benefit from concentrting implementtion of conservtion prctices in loctions with high priority vlue, in most cses. Groundwter rechrge ws significntly higher within ech priority scenrio (top 5%, 10%, 20%, nd 30%) in comprison with historic nd rndom scenrios (figure 6). For groundwter rechrge, five of the six prctices in the historic scenrio performed no better thn the rndom scenrio, nd for conservtion cover, the rndom scenrio performed significntly better. Priority scenrios show n increse in rechrge s the percent level of high priority vlue lnd increses for most prctices, s would be expected, with the exception of nd Tillge Mngement, Mulch Till. Cover Crops hve negtive impct on groundwter rechrge for ll smples, but the impct decreses with incresing percent level of high priority vlue lnd. In comprison to the historic scenrio, our four priority scenrios estimted lrge cumultive improvement in groundwter rechrge for the three most beneficil prctices ( nd Tillge Mngement, No-Till/Strip Till/Direct Seed; Conservtion Cover; nd Mngement, No-Till/Strip Till). The estimtes rnged from billion L y 1 ( JAN/FEB 2013 VOL. 68, NO. 1

8 Figure 4 Priority griculturl lnds for implementing conservtion prctices in order to increse groundwter rechrge nd reduce sedimenttion, differentited for hydrologic soil groups A (eqution 2) nd C (eqution 1). Legend Pw Pw River Pw Pw Wtershed Subwtersheds A soil priorities: Priority vlue High: 4 Low: 0 C soil priorities: Priority vlue High: 4 Low: mi Figure 5 Subwtershed prioritiztion. Scores were given for wtershed position (1 to 4 points); connectivity to the river min stem (either 2 or 4 points); concentrtion of cres judged Moderte, High, or Highest priority in figure 4 (1 to 4 points); nd qulittive ssessment of opportunity bsed on interest of frmers, complementrity with other progrms, nd potentil for impct bsed on lnd ownership fctors (1 to 4 points). Legend Cumultive prioritiztion score 14 (highest) (lowest) Priority subwtersheds: 1 - Brndywine Creek 2 - South Brnch 3 - Mill Creek mi billion gl yr 1 ) for the three prctices t the 30% priority scenrio to billion L y 1 (0.69 billion gl yr 1 ) for the 5% priority scenrio. (The estimtes were derived by dding the verge rechrge for the three prctices for ech of the three simultions nd tking the difference between the priority scenrio mount nd the historic scenrio mount.) Even for the other three prctices, the four priority scenrios hd n estimted, combined improvement in groundwter rechrge of between 707 million nd billion L y 1 (187 million nd 0.27 billion gl yr 1 ). Collectively cross the six prctices, the plcement of prctices in the high priority vlue loctions provides n increse in groundwter rechrge of between 23% nd 36% over the historic scenrio (tble 2). To chieve these dditionl rechrge benefits without prioritizing loctions would hve cost n estimted dditionl US$466,118 to US$722,146. This cost difference ws clculted by first estimting the historic investment in prctices by multiplying the estimted NRCS per-cre pyment for ech prctice (USDA NRCS 2012) by the number of cres for ech prctice in the historic scenrio. Using the modeled gross rechrge mounts, we estimted the cost tht ws pid under the historic scenrio for ech liter of incresed groundwter rechrge. Ech priority scenrio provided n estimte of the number of liters of incresed rechrge for the six prctices. For ech priority scenrio, we multiplied this incresed number of liters by the cost-per-liter rte under the historic scenrio. This clcultion provided n estimte of wht it would hve cost to provide the groundwter rechrge chieved under ech priority scenrio if prctices were distributed without prioritiztion, s in the historic scenrio. Comprisons of potentil benefits from reductions in sedimenttion were more mixed (figure 7). The historic scenrio performed t lest s well s the rndom scenrio for treting the loctions with highest risk of cusing sedimenttion for ll prctices nd significntly better for the Conservtion Cover prctice. For five of the six prctices, ll four priority scenrios hd greter potentil benefit thn the historic nd rndom scenrios, but not ll of these were sttisticlly significnt. In comprison to the historic scenrio, our four priority scenrios hd cumultive improvement in focusing on high-risk loctions for sedimenttion tht rnged from 124% to 231% for the three strongest prc- JAN/FEB 2013 VOL. 68, NO. 1 29

9 Figure 6 Performnce of prioritized loctions for incresed groundwter rechrge under six common conservtion prctices, compred to performnce of historic nd rndomized res. Chnge in groundwter rechrge (in yr 1 ) b b b c d Conservtion cover b b Cover crop b b nd tillge mngement, mulch till nd tillge mngement, no-till/strip till/ direct seed Conservtion prctices mngement, mulch till Legend Historic Rndomized <30% <20% <10% <5% mngement, no-till/strip till Notes: Prioritized loctions were considered in four smples constrined to the top 30%, 20%, 10%, nd 5% of priority lnd. Columns within conservtion prctice type re designted with letters through d indicting significnt difference, such tht two columns with the sme letter re not significntly different in their chnge in groundwter rechrge. tices ( nd Tillge Mngement, Mulch Till; Mngement No-Till/ Strip Till; nd Mngement, Mulch Till). Even for the other three prctices, the four priority scenrios hd n improvement of 1% to 49% per yer. This work illustrtes two mjor points bout ecologicl benefits from griculturl conservtion prctices. First, our results suggest tht historic ppliction of conservtion prctices by the NRCS hs hd remrkble outcomes. From 1999 to 2009, six types of prctices in the Pw Pw River Wtershed incresed groundwter rechrge by nerly one billion L (0.26 billion gl) nnully (figure 6) nd focused lrgely on lnds most t risk for eroding sediment to the river, preventing the deposition of mny tons of sediment (figure 7). The outcomes in preventing sedimenttion re prticulrly notble with the historic scenrio significntly outperforming the rndom scenrio in conservtion cover. This is likely due to the concentrtion of some NRCS progrms on highly erodible soils nd the locl knowledge of conservtion district stff tht ppers to hve directed prctices to mny loctions with high priority vlue. Second, our work nevertheless provides powerful pproch to improve plcement of c c b b Ab d d c bc b b b c c conservtion prctices by strtegiclly locting them bsed on quntittive ecologicl benefits. The prioritized pproch cn help mximize the ecologicl benefits derived from scrce dollrs vilble for USDA progrms promoting conservtion prctices. Our nlysis demonstrtes tht trgeting the loction of conservtion prctices is significntly more efficient in producing environmentl benefits thn historic pproches. For groundwter, trgeting the six prctices t the minimum level (the 30% priority scenrio) still resulted in over 2.35 billion dditionl L (0.62 billion dditionl gl) of groundwter rechrge over the historic scenrio, 23% increse. Achieving these benefits without trgeting would require dditionl conservtion expenditures estimted t US$466,118. Estimted volume of sediment reduction is not vilble, but priority scenrios showed more thn 100% improvement in the verge sedimenttion susceptibility of lnds identified for three of the six prctices. Thus, the prioritized scenrios did better job overll thn the historic scenrio of locting those prctices on griculturl lnds t risk for producing the highest sediment volumes. Since griculturl progrms hve focused especilly on erosive soil loss, it is logicl tht the historic scenrio produced better results for sedimenttion thn groundwter rechrge. It is lso noteworthy tht prioritiztion cn mke such significnt improvement even for results on sedimenttion. Summry nd Conclusions Across the United Sttes, USDA conservtion progrms uthorized by the Frm Bill re by fr the gretest source for incentivizing producers to implement conservtion prctices with the gol of improving environmentl conditions. It is widely recognized tht meeting resonble wter qulity, quntity, nd relted biologicl gols in griculturl wtersheds, like the Pw Pw River Wtershed, will require more efficient nd strtegic use of these progrm dollrs (Mresch et l. 2008). Trgeting prctices to those loctions tht provide reltively high ecologicl benefits per unit cost is the most logicl strtegy for chieving these incresed efficiencies. There re some trgeting mechnisms in plce tht hve improved the performnce of conservtion progrms, like the Conservtion Reserve Progrm nd the Environmentl Qulity Incentives Progrm, but much more could be done (Hnsen nd Hellerstein 2006). Recognizing this need, The Nture Conservncy hs been working with the Vn Buren Conservtion District (Michign), the NRCS in Vn Buren County, Michign, nd Coc-Col Refreshments (CCR), to develop multiscle pproch for generting ecologicl gols nd trgeting conservtion prctices to more efficiently chieve those gols cross the Pw Pw River Wtershed. We gree with Veith et l. (2004) tht optimiztion scenrios re importnt nd useful for setting ecologicl gols t wtershed scles; however, they provide little ssistnce in strtegic, field-scle trgeting of conservtion progrms nd prctices. The lck of detiled, field-level informtion on both the cost nd benefits of conservtion prctices is key fctor hindering such trgeting (Hnsen nd Hellerstein 2006). More specificlly, still needed re dt, models, nd decision tools tht provide resource mngers nd frmers with the bility to work coopertively to ssess costs nd benefits cross rnge of relistic options nd to foster flexible trgeting of prctices tht re suited to the rel-world decision process surrounding frmer prticiption. We believe our pproch in the Pw Pw River Wtershed provides mngers nd frmers with this 30 JAN/FEB 2013 VOL. 68, NO. 1

10 Tble 2 Ten-yer increse in estimted groundwter rechrge for two priority scenrios in comprison to the historic scenrio (1999 to 2009). Additionl cos for incresed Totl cres Estimted Historic Gross Rechrge Increse in rechrge under treted per per-cre investment rechrge increse rechrge historic scenrio Prctice scenrio (c) cost (US$) Scenrio (US$) (L) (L) (%) (US$) Conservtion cover Historic 157,584 2,570,036,033 30% 3,158,273, ,237, ,068 5% 3,298,025, ,989, ,637 Cover crop 1, Historic 1,051,891-2,607,927,529 30% -2,302,224, ,702, ,303 5% -2,105,149, ,777, ,792 nd tillge Historic 93,924 1,092,773,842 mngement, mulch 30% 1,187,196,720 94,422, ,116 till 5% 1,222,482, ,708, ,148 nd tillge Historic 249,816 3,336,569,825 mngement, no-till/ 30% 4,095,822, ,253, ,847 strip till/direct seed 5% 4,494,133,033 1,157,563, ,669 mngement, 1, Historic 238,404 2,712,829,400 mulch till 30% 3,020,277, ,448, ,019 5% 3,103,881, ,052, ,366 mngement, Historic 231,724 3,108,533,025 no-till/strip till 30% 3,408,353, ,820, ,350 5% 3,847,809, ,276, ,109 Totl 6,972.4 Historic 2,021,490 10,212,814,596 30% 12,567,699,847 2,354,885, ,118 5% 13,861,183,701 3,648,369, ,146 Notes: Dollr figures in the fr right column indicte the cost of providing the dditionl rechrge benefits ccrued under priority scenrios t the cost per liter provided under the historic scenrio. The historic investment is derived from Nturl Resources Conservtion Service per-cre costs for ech prctice multiplied by the number of cres receiving the prctice in the wtershed from 1999 to 2009 (USDA NRCS 2012). flexibility needed to ssess options in terms of both plcement nd type of prctices. Our pproch nd suite of tools certinly provide direct support to mngers for the trgeting of conservtion prctices. However, our pproch lso indirectly fcilittes trgeting by both educting frmers nd mking them directly involved in the decision mking process. Numerous studies in the 1980s imed to identify fctors tht led some frmers to invest in conservtion while others did not. These studies reveled tht frmers tht understood the linkges between conservtion prctices nd environmentl benefits were more likely to prticipte nd lso invest more, ll other fctors being equl (Ervin nd Ervin 1982; Norris nd Btie 1987; Gould et l. 1989). Frmers consider severl fctors when deciding whether to prticipte in conservtion progrms, including crop production of the site, contrct length, prctice type nd mintennce, pyment rte, nd environmentl benefits, if tht informtion is vilble (Hnsen nd Hellerstein 2006). Our groundwter clcultor llows frmers to ctully ssess options for severl of these fctors. Becuse of the success of this decision tool, The Nture Conservncy is now working on similr field-scle tools for sediments nd nutrients. Our pproch hs hd multiple direct benefits towrd incresing conservtion efforts in the Pw Pw River Wtershed. While the historic ppliction of conservtion prctices to the griculturl lndscpe hs resulted in tremendous ecologicl outcomes, we cn chieve even more ecologicl benefit t n equivlent cost through prioritizing griculturl lnds where the gretest ecologicl benefits will be produced. Clcultion of ecologicl benefits provides highly vluble mesure of our success in ddition to progrmmtic mesures, such s the number of cres treted with conservtion prctice or the number of contrcts processed. We believe tht the outcomes of USDA cost-shre nd incentive funds could be gretly enhnced by incorporting this pproch. This would sve limited finncil resources nd chieve the gretest ecosystem benefits from conservtion prctices pplied in griculturl lndscpes. Furthermore, our nlyses demonstrte tht trgeting need not be rigid. We cn chieve significntly greter benefits by focusing on the top 30% of sites, not just the top 5%. Finlly, we demonstrte tht while the outputs of models like SWAT JAN/FEB 2013 VOL. 68, NO. 1 31