Hydrological Connectivity Between Headwater Streams and Downstream Waters: How Science Can Inform Policy1

Abstract: In January 2001, the U.S. Supreme Court ruled that the U.S. Army Corps of Engineers exceeded its statutory authority by asserting Clean Water Act (CWA) jurisdiction over non‐navigable, isolated, intrastate waters based solely on their use by migratory birds. The Supreme Court’s majority opinion addressed broader issues of CWA jurisdiction by implying that the CWA intended some “connection” to navigability and that isolated waters need a “significant nexus” to navigable waters to be jurisdictional. Subsequent to this decision (SWANCC), there have been many lawsuits challenging CWA jurisdiction, many of which are focused on headwater, intermittent, and ephemeral streams. To inform the legal and policy debate surrounding this issue, we present information on the geographic distribution of headwater streams and intermittent and ephemeral streams throughout the U.S., summarize major findings from the scientific literature in considering hydrological connectivity between headwater streams and downstream waters, and relate the scientific information presented to policy issues surrounding the scope of waters protected under the CWA. Headwater streams comprise approximately 53% (2,900,000 km) of the total stream length in the U.S., excluding Alaska, and intermittent and ephemeral streams comprise approximately 59% (3,200,000 km) of the total stream length and approximately 50% (1,460,000 km) of the headwater stream length in the U.S., excluding Alaska. Hillslopes, headwater streams, and downstream waters are best described as individual elements of integrated hydrological systems. Hydrological connectivity allows for the exchange of mass, momentum, energy, and organisms longitudinally, laterally, vertically, and temporally between headwater streams and downstream waters. Via hydrological connectivity, headwater, intermittent and ephemeral streams cumulatively contribute to the functional integrity of downstream waters; hydrologically and ecologically, they are a part of the tributary system. As this debate continues, scientific input from multiple fields will be important for policymaking at the federal, state, and local levels and to inform water resource management regardless of the level at which those decisions are being made. Strengthening the interface between science, policy, and public participation is critical if we are going to achieve effective water resource management.     

Comparing the Extent and Permanence of Headwater Streams From Two Field Surveys to Values From Hydrographic Databases and Maps

Supreme Court cases have questioned if jurisdiction under the Clean Water Act extends to water bodies such as streams without year‐round flow. Headwater streams are central to this issue because many periodically dry, and because little is known about their influence on navigable waters. An accurate account of the extent and flow permanence of headwater streams is critical to estimating downstream contributions. We compared the extent and permanence of headwater streams from two field surveys with values from databases and maps. The first used data from 29 headwater streams in nine U.S. forests, whereas the second had data from 178 headwater streams in Oregon. Synthetic networks developed from the nine‐forest survey indicated that 33 to 93% of the channel lacked year‐round flow. Seven of the nine forests were predicted to have >200% more channel length than portrayed in the high‐resolution National Hydrography Dataset (NHD). The NHD and topographic map classifications of permanence agreed with ~50% of the field determinations across ~300 headwater sites. Classification agreement with the field determinations generally increased with increasing resolution. However, the flow classification on soil maps only agreed with ~30% of the field determination despite depicting greater channel extent than other maps. Maps that include streams regardless of permanence and size will aid regulatory decisions and are fundamental to improving water quality monitoring and models.     

Hydrologic Connectivity and the Contribution of Stream Headwaters to Ecological Integrity at Regional Scales1

Abstract: Cumulatively, headwater streams contribute to maintaining hydrologic connectivity and ecosystem integrity at regional scales. Hydrologic connectivity is the water‐mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle. Headwater streams compose over two‐thirds of total stream length in a typical river drainage and directly connect the upland and riparian landscape to the rest of the stream ecosystem. Altering headwater streams, e.g., by channelization, diversion through pipes, impoundment and burial, modifies fluxes between uplands and downstream river segments and eliminates distinctive habitats. The large‐scale ecological effects of altering headwaters are amplified by land uses that alter runoff and nutrient loads to streams, and by widespread dam construction on larger rivers (which frequently leaves free‐flowing upstream portions of river systems essential to sustaining aquatic biodiversity). We discuss three examples of large‐scale consequences of cumulative headwater alteration. Downstream eutrophication and coastal hypoxia result, in part, from agricultural practices that alter headwaters and wetlands while increasing nutrient runoff. Extensive headwater alteration is also expected to lower secondary productivity of river systems by reducing stream‐system length and trophic subsidies to downstream river segments, affecting aquatic communities and terrestrial wildlife that utilize aquatic resources. Reduced viability of freshwater biota may occur with cumulative headwater alteration, including for species that occupy a range of stream sizes but for which headwater streams diversify the network of interconnected populations or enhance survival for particular life stages. Developing a more predictive understanding of ecological patterns that may emerge on regional scales as a result of headwater alterations will require studies focused on components and pathways that connect headwaters to river, coastal and terrestrial ecosystems. Linkages between headwaters and downstream ecosystems cannot be discounted when addressing large‐scale issues such as hypoxia in the Gulf of Mexico and global losses of biodiversity.     

GIS‐Based Stream Classification in a Mountain Watershed for Jurisdictional Evaluation

This study analyzed stream characteristics in a mountain watershed in southwestern Colorado and developed a three‐level hierarchical classification scheme using national datasets to demonstrate jurisdictional evaluation as “waters of the United States (U.S.)” under U.S. Clean Water Act Section 404 at the watershed scale. The National Hydrography Dataset and USGS StreamStats were used with field observations to classify streams in the 53 km² Cement Creek Watershed based on flow duration (Level 1), stream order (Level 2), and other biophysical metrics (Level 3). Kruskal‐Wallis tests and discriminant analysis showed significant differences among Level 2 classes. Level 3 classification used cluster analysis for stream length, distance to the downstream traditional navigable water (TNW), and the ratio of mean annual flow from the source stream to the TNW. Results showed all perennial and intermittent streams are jurisdictional relatively permanent waters (RPWs), which include over a third of all streams, 64% are intermittent or ephemeral, and almost half are ephemeral first order. All ephemeral reaches are non‐RPWs requiring significant nexus evaluation to determine jurisdiction. These ephemeral first‐order streams can contribute 5% of the annual flow to the TNW at the confluence, while the Cement Creek main stem contributes 21% of the TNW flow. The study demonstrated that the classification provides key biophysical and regulatory information to aid jurisdictional evaluations in mountain watersheds.     

Ecological Linkages Between Headwaters and Downstream Ecosystems: Transport of Organic Matter,Invertebrates, and Wood Down Headwater Channels1

Abstract: Headwater streams make up a large proportion of the total length and watershed area of fluvial networks, and are partially characterized by the large volume of organic matter (large wood, detritus, and dissolved organic matter) and invertebrate inputs from the riparian forest, relative to stream size. Much of those inputs are exported to downstream reaches through time where they potentially subsidize river communities. The relative rates, timing, and conversion processes that carry inputs from small streams to downstream reaches are reasonably well quantified. For example, larger particles are converted to smaller particles, which are more easily exported. Also, dissolved organic matter and surface biofilms are converted to larger particles which can be more easily intercepted by consumers. However, the quality of these materials as it affects biological activity downstream is not well known, nor is the extent to which timing permits biological use of those particles. These ecological unknowns need to be resolved. Further, land uses may disrupt and diminish material transport to downstream reaches by removing sources (e.g., forest harvest), by affecting transport and decomposition processes (e.g., flow regulation, irrigation, changes in biotic communities), and by altering mechanisms of storage within headwaters (e.g., channelization). We present conceptual models of energy and nutrient fluxes that outline small stream processes and pathways important to downstream communities, and we identify informational gaps that, if filled, could significantly advance the understanding of linkages between headwater streams and larger rivers. The models, based on empirical evidence and best professional judgment, suggest that navigable waters are significantly influenced by headwater streams through hydrological and ecological connectivities, and land use can dramatically influence these natural connectivities, impacting downstream riverine ecosystems.     

Headwater Influences on Downstream Water Quality

We investigated the influence of riparian and whole watershed land use as a function of stream size on surface water chemistry and assessed regional variation in these relationships. Sixty-eight watersheds in four level III U.S. EPA ecoregions in eastern Kansas were selected as study sites. Riparian land cover and watershed land use were quantified for the entire watershed, and by Strahler order. Multiple regression analyses using riparian land cover classifications as independent variables explained among-site variation in water chemistry parameters, particularly total nitrogen (41%), nitrate (61%), and total phosphorus (63%) concentrations. Whole watershed land use explained slightly less variance, but riparian and whole watershed land use were so tightly correlated that it was difficult to separate their effects. Water chemistry parameters sampled in downstream reaches were most closely correlated with riparian land cover adjacent to the smallest (first-order) streams of watersheds or land use in the entire watershed, with riparian zones immediately upstream of sampling sites offering less explanatory power as stream size increased. Interestingly, headwater effects were evident even at times when these small streams were unlikely to be flowing. Relationships were similar among ecoregions, indicating that land use characteristics were most responsible for water quality variation among watersheds. These findings suggest that nonpoint pollution control strategies should consider the influence of small upland streams and protection of downstream riparian zones alone is not sufficient to protect water quality.     

The Contribution of Headwater Streams to Biodiversity in River Networks1

Abstract: The diversity of life in headwater streams (intermittent, first and second order) contributes to the biodiversity of a river system and its riparian network. Small streams differ widely in physical, chemical, and biotic attributes, thus providing habitats for a range of unique species. Headwater species include permanent residents as well as migrants that travel to headwaters at particular seasons or life stages. Movement by migrants links headwaters with downstream and terrestrial ecosystems, as do exports such as emerging and drifting insects. We review the diversity of taxa dependent on headwaters. Exemplifying this diversity are three unmapped headwaters that support over 290 taxa. Even intermittent streams may support rich and distinctive biological communities, in part because of the predictability of dry periods. The influence of headwaters on downstream systems emerges from their attributes that meet unique habitat requirements of residents and migrants by: offering a refuge from temperature and flow extremes, competitors, predators, and introduced species; serving as a source of colonists; providing spawning sites and rearing areas; being a rich source of food; and creating migration corridors throughout the landscape. Degradation and loss of headwaters and their connectivity to ecosystems downstream threaten the biological integrity of entire river networks.     

Estimating Contributions of Nitrate and Herbicides From Groundwater to Headwater Streams,Northern Atlantic Coastal Plain,United States1

Abstract: Groundwater transport often complicates understanding of surface‐water contamination. We estimated the regional flux of nitrate and selected herbicides from groundwater to nontidal headwater streams of the Atlantic Coastal Plain (New Jersey through North Carolina) based on late‐winter or spring base‐flow samples from 174 streams. Sampled streams were selected randomly, and flux estimates are based on resulting population estimates rather than on empirical models, which have been used previously for similar estimates. Base‐flow flux in the estimated 8,834 headwater streams of the study area are an estimated 21,200 kg/day of nitrate (as N) and 5.83, 0.565, and 20.7 kg/day of alachlor, atrazine, and metolachlor (and selected degradates), respectively. Base‐flow flux of alachlor and metolachlor is <3% of the total base‐flow flux of those compounds plus degradates. Base‐flow flux of nitrate and herbicides as a percentage of applications is typically highest in well‐drained areas and lowest in areas with abundant poor drainage and anoxic conditions. In Coastal Plain watersheds of Albemarle and Pamlico Sounds, <2% of applied nitrogen reaches headwater streams as base flow. On the Delmarva Peninsula part of the Chesapeake Bay watershed, however, more than 10% of such applications are transported through groundwater to streams, and base‐flow nitrate flux represents 70% of total nitrogen flux in headwater streams.     

Application of SPARROW Modeling to Understanding Contaminant Fate and Transport from Uplands to Streams

Understanding spatial variability in contaminant fate and transport is critical to efficient regional water‐quality restoration. An approach to capitalize on previously calibrated spatially referenced regression (SPARROW) models to improve the understanding of contaminant fate and transport was developed and applied to the case of nitrogen in the 166,000 km² Chesapeake Bay watershed. A continuous function of four hydrogeologic, soil, and other landscape properties significant (α = 0.10) to nitrogen transport from uplands to streams was evaluated and compared among each of the more than 80,000 individual catchments (mean area, 2.1 km²) in the watershed. Budgets (including inputs, losses or net change in storage in uplands and stream corridors, and delivery to tidal waters) were also estimated for nitrogen applied to these catchments from selected upland sources. Most (81%) of such inputs are removed, retained, or otherwise processed in uplands rather than transported to surface waters. Combining SPARROW results with previous budget estimates suggests 55% of this processing is attributable to denitrification, 23% to crop or timber harvest, and 6% to volatilization. Remaining upland inputs represent a net annual increase in landscape storage in soils or biomass exceeding 10 kg per hectare in some areas. Such insights are important for planning watershed restoration and for improving future watershed models.     

Controls on Nutrients Across a Prairie Stream Watershed: Land Use and Riparian Cover Effects

Nutrient inputs generally are increased by human-induced land use changes and can lead to eutrophication and impairment of surface waters. Understanding the scale at which land use influences nutrient loading is necessary for the development of management practices and policies that improve water quality. The authors assessed the relationships between land use and stream nutrients in a prairie watershed dominated by intermittent stream flow in the first-order higher elevation reaches. Total nitrogen, nitrate, and phosphorus concentrations were greater in tributaries occupying the lower portions of the watershed, closely mirroring the increased density of row crop agriculture from headwaters to lower-elevation alluvial areas. Land cover classified at three spatial scales in each sub-basin above sampling sites (riparian in the entire catchment, catchment land cover, and riparian across the 2 km upstream) was highly correlated with variation in both total nitrogen (r² = 53%, 52%, and 49%, respectively) and nitrate (r² = 69%, 65%, and 56%, respectively) concentrations among sites. However, phosphorus concentrations were not significantly associated with riparian or catchment land cover classes at any spatial scale. Separating land use from riparian cover in the entire watershed was difficult, but riparian cover was most closely correlated with in-stream nutrient concentrations. By controlling for land cover, a significant correlation of riparian cover for the 2 km above the sampling site with in-stream nutrient concentrations could be established. Surprisingly, land use in the entire watershed, including small intermittent streams, had a large influence on average downstream water quality although the headwater streams were not flowing for a substantial portion of the year. This suggests that nutrient criteria may not be met only by managing permanently flowing streams.     

A Spatially Explicit Model for Mapping Headwater Streams

Headwater streams are the primary sources of water in a drainage network and serve as a critical hydrologic link between the surrounding landscape and larger, downstream surface waters. Many states, including North Carolina, regulate activity in and near headwater streams for the protection of water quality and aquatic resources. A fundamental tool for regulatory management is an accurate representation of streams on a map. Limited resources preclude field mapping every headwater stream and its origin across a large region. It is more practical to develop a model for headwater streams based on a sample of field data that can then be extrapolated to a larger area of interest. The North Carolina Division of Water Quality has developed a cost‐effective method for modeling and mapping the location, length, and flow classification (intermittent and perennial) of headwater streams. We used a multiple logistic regression approach that combined field data and terrain derivatives for watersheds located in the Triassic Basins ecoregion. Field data were collected using a standard methodology for identifying headwater streams and origins. Terrain derivatives were generated from digital elevation models interpolated from bare‐earth Light Detection and Range data. Model accuracies greater than 80% were achieved in classifying stream presence and absence, stream length and perennial stream length, but were not as consistent in predicting intermittent stream length.     

Physical and Temporal Isolation of Mountain Headwater Streams in the Western Mojave Desert,Southern California1

Abstract: Streams draining mountain headwater areas of the western Mojave Desert are commonly physically isolated from downstream hydrologic systems such as springs, playa lakes, wetlands, or larger streams and rivers by stream reaches that are dry much of the time. The physical isolation of surface flow in these streams may be broken for brief periods after rainfall or snowmelt when runoff is sufficient to allow flow along the entire stream reach. Despite the physical isolation of surface flow in these streams, they are an integral part of the hydrologic cycle. Water infiltrated from headwater streams moves through the unsaturated zone to recharge the underlying ground‐water system and eventually discharges to support springs, streamflow, isolated wetlands, or native vegetation. Water movement through thick unsaturated zones may require several hundred years and subsequent movement through the underlying ground‐water systems may require many thousands of years – contributing to the temporal isolation of mountain headwater streams.     

Evaluation of a denitrification wall to reduce surface water nitrogen loads

Denitrification walls have significantly reduced nitrogen concentrations in groundwater for at least 15 yr. This has spurred interest in developing methods to efficiently increase capture volume to reduce N loads in larger watersheds. The objective of this study was to maximize treatment volume by locating a wall where a large groundwatershed was funneled toward seepage slope headwaters. Nitrogen concentration and load were measured before and after wall installation in paired treatment and control streams. Beginning 2 d after installation, nitrogen concentration in the treatment stream declined from 6.7 ± 1.2 to 3.9 ± 0.78 mg L and total N loading rate declined by 65% (391 kg yr) with no corresponding decline in the control watershed. This wall, which only comprised 10 to 11% of the edge of field area that contributed to the treatment watershed, treated approximately 60% of the stream discharge, which confirmed the targeted approach. The total load reduction measured in the stream 155 m downstream from the wall (340 kg yr) was higher than that found in another study that measured load reductions in groundwater wells immediately around the wall (228 kg yr). This indicated the possibility of an extended impact on denitrification from carbon exported beyond the wall. This extended impact was inauspiciously confirmed when oxygen levels at the stream headwaters temporarily declined for 50 d. This research indicates that targeting walls adjacent to streams can effectively reduce N loading in receiving waters, although with a potentially short-term impact on water quality.     

Computing Atmospheric Nutrient Loads to the Chesapeake Bay Watershed and Tidal Waters

Application of integrated Chesapeake Bay models of the airshed, watershed, and estuary support air and water nitrogen controls in the Chesapeake. The models include an airshed model of the Mid‐Atlantic region which tracks the estimated atmospheric deposition loads of nitrogen to the watershed, tidal Bay, and adjacent coastal ocean. The three integrated models allow tracking of the transport and fate of nitrogen air emissions, including deposition in the Chesapeake watershed, the subsequent uptake, transformation, and transport to Bay tidal waters, and their ultimate influence on Chesapeake water quality. This article describes the development of the airshed model, its application to scenarios supporting the Chesapeake Total Maximum Daily Load (TMDL), and key findings from the scenarios. Key findings are that the atmospheric deposition loads are among the largest input loads of nitrogen in the watershed, and that the indirect nitrogen deposition loads to the watershed, which are subsequently delivered to the Bay are larger than the direct loads of atmospheric nitrogen deposition to Chesapeake tidal waters. Atmospheric deposition loads of nitrogen deposited in coastal waters, which are exchanged with the Chesapeake, are also estimated. About half the atmospheric deposition loads of nitrogen originate from outside the Chesapeake watershed. For the first time in a TMDL, the loads of atmospheric nitrogen deposition are an explicit part of the TMDL load reductions.     

Sources of Suspended-Sediment Flux in Streams of the Chesapeake Bay Watershed: A Regional Application of the SPARROW Model1

Brakebill, John W., Scott W. Ator, and Gregory E. Schwarz, 2010. Sources of Suspended-Sediment Flux in Streams of the Chesapeake Bay Watershed: A Regional Application of the SPARROW Model. Journal of the American Water Resources Association (JAWRA) 46(4): 757-776. DOI: 10.1111/j.1752-1688.2010.00450.x Abstract: We describe the sources and transport of fluvial suspended sediment in nontidal streams of the Chesapeake Bay watershed and vicinity. We applied SPAtially Referenced Regressions on Watershed attributes, which spatially correlates estimated mean annual flux of suspended sediment in nontidal streams with sources of suspended sediment and transport factors. According to our model, urban development generates on average the greatest amount of suspended sediment per unit area (3,928 Mg/km²/year), although agriculture is much more widespread and is the greatest overall source of suspended sediment (57 Mg/km²/year). Factors affecting sediment transport from uplands to streams include mean basin slope, reservoirs, physiography, and soil permeability. On average, 59% of upland suspended sediment generated is temporarily stored along large rivers draining the Coastal Plain or in reservoirs throughout the watershed. Applying erosion and sediment controls from agriculture and urban development in areas of the northern Piedmont close to the upper Bay, where the combined effects of watershed characteristics on sediment transport have the greatest influence may be most helpful in mitigating sedimentation in the bay and its tributaries. Stream restoration efforts addressing floodplain and bank stabilization and incision may be more effective in smaller, headwater streams outside of the Coastal Plain.     

The Role of Ground Water in Generating Streamflow in Headwater Areas and in Maintaining Base Flow1

Abstract: The volume and sustainability of streamflow from headwaters to downstream reaches commonly depend on contributions from ground water. Streams that begin in extensive aquifers generally have a stable point of origin and substantial discharge in their headwaters. In contrast, streams that begin as discharge from rocks or sediments having low permeability have a point of origin that moves up and down the channel seasonally, have small incipient discharge, and commonly go dry. Nearly all streams need to have some contribution from ground water in order to provide reliable habitat for aquatic organisms. Natural processes and human activities can have a substantial effect on the flow of streams between their headwaters and downstream reaches. Streams lose water to ground water when and where their head is higher than the contiguous water table. Although very common in arid regions, loss of stream water to ground water also is relatively common in humid regions. Evaporation, as well as transpiration from riparian vegetation, causing ground‐water levels to decline also can cause loss of stream water. Human withdrawal of ground water commonly causes streamflow to decline, and in some regions has caused streams to cease flowing.     

Using GIS to Delineate Headwater Stream Origins in the Appalachian Coalfields of Kentucky

Headwater streams have a significant nexus or physical, chemical, and/or biological connection to downstream reaches. Generally, defined as 1st‐3rd order with ephemeral, intermittent, or perennial flow regimes, these streams account for a substantial portion of the total stream network particularly in mountainous terrain. Due to their often remote locations, small size, and large numbers, conducting field inventories of headwater streams is challenging. A means of estimating headwater stream location and extent according to flow regime type using publicly available spatial data is needed to simplify this complex process. Using field‐collected headwater point of origin data from three control watersheds, streams were characterized according to a set of spatial parameters related to topography, geology, and soils. These parameters were (1) compared to field‐collected point of origin data listed in three nearby Jurisdictional Determinations, (2) used to develop a geographic information system (GIS)‐based stream network for identifying ephemeral, intermittent, and perennial streams, and (3) applied to a larger watershed and compared to values obtained using the high‐resolution National Hydrography Dataset (NHD). The parameters drainage area and local valley slope were the most reliable predictors of flow regime type. Results showed the high‐resolution NHD identified no ephemeral streams and 9 and 65% fewer intermittent and perennial streams, respectively, than the GIS model.     

Spatial Convergence in Major Dissolved Ion Concentrations and Implications of Headwater Mining for Downstream Water Quality

Spatial patterns in major dissolved solute concentrations were examined to better understand impact of surface coal mining in headwaters on downstream water chemistry. Sixty sites were sampled seasonally from 2012 to 2014 in an eastern Kentucky watershed. Watershed areas (WA) ranged from 1.6 to 400.5 km² and were mostly forested (58%–95%), but some drained as much as 31% surface mining. Measures of total dissolved solutes and most component ions were positively correlated with mining. Analytes showed strong convergent spatial patterns with high variability in headwaters (<15 km² WA) that stabilized downstream (WA > 75 km²), indicating hydrologic mixing primarily controls downstream values. Mean headwater solute concentrations were a good predictor of downstream values, with % differences ranging from 0.55% (Na⁺) to 28.78% (Mg²⁺). In a mined scenario where all headwaters had impacts, downstream solute concentrations roughly doubled. Alternatively, if mining impacts to headwaters were minimized, downstream solute concentrations better approximated the 300 μS/cm conductivity criterion deemed protective of aquatic life. Temporal variability also had convergent spatial patterns and mined streams were less variable due to unnaturally stable hydrology. The highly conserved nature of dissolved solutes from mining activities and lack of viable treatment options suggest forested, unmined watersheds would provide dilution that would be protective of downstream aquatic life.     

A CRITIQUE OF WATERSHED MANAGEMENT EFFORTS IN THE LOWER MISSISSIPPI ALLUVIAL PLAIN1

ABSTRACT: Integrated watershed management in the Lower Mississippi Alluvial Plain (Delta) requires blending federal, state, and local authority. The federal government has preeminent authority over interstate navigable waters. Conversely, state and local governments have authority vital for comprehensive watershed management. In the Delta, integrating three broad legal and administrative regimes: (1) flood control, (2) agricultural watershed management, and (3) natural resources and environmental management, is vital for comprehensive intrastate watershed, and interstate river basin management. Federal Mississippi River flood control projects incorporated previous state and local efforts. Similarly, federal agricultural programs in the River's tributary headwaters adopted watershed management and were integrated into flood control efforts. These legal and administrative regimes implement national policy largely in cooperation with and through technical and financial assistance to local agencies such as levee commissions and soil and water conservation districts. This administrative infrastructure could address new national concerns such as nonpoint source pollution which require a watershed scale management approach. However, the natural resources and environmental management regime lacks a local administrative infrastructure. Many governmental and non governmental coordinating organizations have recently formed to address this shortcoming in the Delta. With federal and state leadership and support, these organizations could provide mechanisms to better integrate natural resources and environmental issues into the Delta's existing local administrative infrastructure.