An urban observatory for quantifying phosphorus and suspended solid loads in combined natural and stormwater conveyances

Water quality in urban streams and stormwater systems is highly dynamic, both spatially and temporally, and can change drastically during storm events. Infrequent grab samples commonly collected for estimating pollutant loadings are insufficient to characterize water quality in many urban water systems. In situ water quality measurements are being used as surrogates for continuous pollutant load estimates; however, relatively few studies have tested the validity of surrogate indicators in urban stormwater conveyances. In this paper, we describe an observatory aimed at demonstrating the infrastructure required for surrogate monitoring in urban water systems and for capturing the dynamic behavior of stormwater-driven pollutant loads. We describe the instrumentation of multiple, autonomous water quality and quantity monitoring sites within an urban observatory. We also describe smart and adaptive sampling procedures implemented to improve data collection for developing surrogate relationships and for capturing the temporal and spatial variability of pollutant loading events in urban watersheds. Results show that the observatory is able to capture short-duration storm events within multiple catchments and, through inter-site communication, sampling efforts can be synchronized across multiple monitoring sites.     

Generating Synthetic Rainfall on Various Timescales—Daily, Monthly and Yearly

The main objective of this paper is to present a model for generating synthetic rainfall totals on various timescales to be applicable for a variety of uses. Many large-scale ecological and water resource models require daily, monthly and yearly rainfall data as input to the model. As historical data provides only one realisation, synthetic generated rainfall totals are needed to assess the impact of rainfall variability on water resources systems (Srikanthan, In: MODSIM2005, Melbourne, Dec. 2005, pp. 1915–1921, 2005). Thus, our preferred model should simulate rainfall for yearly, monthly and daily periods. We believe that, for water supply issues, no higher resolution is needed, although higher resolution would be useful in models designed to measure the risk of local flooding. The critical factors are daily, monthly and yearly totals and daily, monthly and yearly variation. A model for generating yearly totals will be described using traditional time series methods. This model, along with a similarly constructed daily generation model by Piantadosi et al. (A New Model for Correlated Daily Rainfall, 2008), will be cascaded to start with a synthetic yearly total, then generate a synthetic sequence of monthly totals (through selection from a large number of realisations) that match the yearly total, and subsequently perform a similar operation for sequences of daily totals to match the required monthly totals. We present a new model for the generation of synthetic monthly rainfall data, which we demonstrate for Parafield in Adelaide, South Australia. The rainfall for each month of the year is modelled as a non-negative random variable from a mixed distribution with either a zero outcome or a strictly positive outcome. We use maximum likelihood to find parameters for both the probability of a zero outcome and the gamma distribution that best matches the observed probability density for the strictly positive outcomes. We describe a new model that generates correlated monthly rainfall totals using a diagonal band copula with a single parameter to generate lag-1 correlated random numbers. Our model preserves the marginal monthly distributions and, hence, also preserves the monthly and yearly means. We show that, for Parafield, the correlation between rainfall totals for successive months is not significant, and so, it is reasonable to assume independence. This is, however, not true for daily rainfall. We describe a new model that generates correlated daily rainfall totals using a diagonal band copula with a single parameter to generate lag-1 correlated random numbers. This is an extended version of a paper presented at the 17th Biennial Congress on Modelling and Simulation, Christchurch, New Zealand, December 2007.     

Urban stormwater harvesting and reuse: a probe into the chemical, toxicology and microbiological contaminants in water quality

Stormwater is one of the last major untapped urban water resources that can be exploited as an alternative water source in Australia. The information in the current Australian Guidelines for Water Recycling relating to stormwater harvesting and reuse only emphasises on a limited number of stormwater quality parameters. In order to supply stormwater as a source for higher value end-uses, a more comprehensive assessment on the potential public health risks has to be undertaken. Owing to the stochastic variations in rainfall, catchment hydrology and also the types of non-point pollution sources that can provide contaminants relating to different anthropogenic activities and catchment land uses, the characterisation of public health risks in stormwater is complex, tedious and not always possible through the conventional detection and analytical methods. In this study, a holistic approach was undertaken to assess the potential public health risks in urban stormwater samples from a medium-density residential catchment. A combined chemical–toxicological assessment was used to characterise the potential health risks arising from chemical contaminants, while a combination of standard culture methods and quantitative polymerase chain reaction (qPCR) methods was used for detection and quantification of faecal indicator bacteria (FIB) and pathogens in urban stormwater. Results showed that the concentration of chemical contaminants and associated toxicity were relatively low when benchmarked against other alternative water sources such as recycled wastewater. However, the concentrations of heavy metals particularly cadmium and lead have exceeded the Australian guideline values, indicating potential public health risks. Also, high numbers of FIB were detected in urban stormwater samples obtained from wet weather events. In addition, qPCR detection of human-related pathogens suggested there are frequent sewage ingressions into the urban stormwater runoff during wet weather events. Further water quality monitoring study will be conducted at different contrasting urban catchments in order to undertake a more comprehensive public health risk assessment for urban stormwater.     

High-frequency measurements reveal spatial and temporal patterns of dissolved organic matter in an urban water conveyance

Stormwater runoff in urban areas can contribute high concentrations of dissolved organic matter (DOM) to receiving waters, potentially causing impairment to the aquatic ecosystem of urban streams and downstream water bodies. Compositional changes in DOM due to storm events in forested, agricultural, and urban landscapes have been well studied, but in situ sensors have not been widely applied to monitor stormwater contributions in urbanized areas, leaving the spatial and temporal characteristics of DOM within these systems poorly understood. We deployed fluorescent DOM (FDOM) sensors at upstream and downstream locations within a study reach to characterize the spatial and temporal changes in DOM quantity and sources within an urban water conveyance that receives stormwater runoff. Baseflow FDOM decreased over the summer season as seasonal flows upstream transported less DOM. FDOM fluctuated diurnally, the amplitude of which also declined as the summer season progressed. During storms, FDOM concentrations were rapidly elevated to values orders of magnitude greater than baseflow measurements, with greater concentrations at the downstream monitoring site, revealing high contributions from stormwater outfalls between the two locations. Observations from custom, in situ fluorometers resembled results obtained using laboratory methods for identifying DOM source material and indicated that DOM transitioned to a more microbially derived composition as the summer season progressed, while stormwater contributions contributed DOM from terrestrial sources. Deployment of a mobile sensing platform during varying flow conditions captured spatial changes in DOM concentration and composition and revealed contributions of DOM from outfalls during stormflows that would have otherwise been unobserved.     

Characteristics of Stormwater Quality from Two Urban Watersheds in Singapore

This paper presents the results of a study on the quality of stormwater runoff from two adjacent urban watersheds in Singapore. The study involved continuous recording of rainfall and streamflow within the basins, and systematic sampling of storm runoff during rainfall events. The water samples collected were analysed for its physical and chemical constituents. The ranges and mean concentrations of common quality parameters have been established, and the flushing effects of selected parameters were studied. Correlations of event mean concentrations and pollution loads of total suspended solids and chemical oxygen demand to both antecedent dry weather period and rainfall characteristics were also carried out.     

Assessing dam implementation impact on threatened carnivores: the case of Alqueva in SE Portugal

Large dam construction in water deficient areas is a management decision often controversial. Besides providing water storage, economical benefits, and a source of renewable energy, the construction and flooding caused by large dams cause disruptions in natural systems. We monitored the pre- and post-Alqueva dam impacts on the threatened carnivore species (polecat, otter, wildcat and Iberian lynx) populations in SE Portugal, and assessed which factors mostly contribute to post-dam distribution. Major short term impacts of large dams are: (1) increase in accessibility and human presence; (2) movement of heavy machinery and dam-workers; (3) deforestation with habitat loss and fragmentation; (4) change from lotic to lentic system; (5) lower prey availability and harsher capture; and (6) changes in land use adjacent to the reservoir. Thus, the response to those impacts can be predicted as a decline of polecat, wildcat and lynx distribution ranges, and a recovery of the otter from the severe short term impacts. Our results corroborate this hypothesis for all the species, especially during deforestation/early flooding. Otter's distribution range increased in the phase of greater impact, with a subsequent decrease with flooding. Our results suggest carnivores used "escape" areas with favourable habitat and prey conditions, however, the areas with higher probability of species presence decreased by two fold showing a drastic range reduction. To ensure populations' survival of these charismatic threatened carnivore populations of Mediterranean landscapes of south-east Portugal, we propose continuing the monitoring program and the development of a conservation program for the subsisting areas of optimal and suboptimal habitats.     

The temporal changes in road stormwater runoff quality and the implications to first flush control in Chongqing, China

This study investigates the quality of stormwater runoff from a driveway in the southwest mountainous urban area of Chongqing, China, from 2010 to 2011. The results showed that the mean concentrations of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were 4.1, 2.4, and 2.2 times the grade V levels of the national surface water standard of China. The pollutant concentration peak preceded or synchronized with the rainfall intensity peak and occurred 10 min after the runoff started. The significant high pollutant concentration in the initial stage of the rainfall suggested that first flush control is necessary, especially for the most polluted constitutes, such as total suspended solids, COD, and TN. Three potential pollution sources were identified: the atmospheric dry and wet deposition (TN, NO₃ ^?-N, NH₄ ⁺-N, and DCu), the road sediment and materials (total suspended solids, COD, and TP), and the vehicle emissions (DPb and DZn). Therefore, this study indicates that reductions in road sediments and material pollution and dry and wet deposition should be the priority factors for pollution control of road stormwater runoff in mountainous urban areas.     

Impact of urbanization on the concentrations and distribution of organic contaminants in boreal lake sediments

The main goal of this study was to evaluate the impacts of a middle-sized Finnish urban area on the quality of sediments in an adjacent boreal lake. We investigated the sources and distribution of organic pollutants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)) in the sediments from urban stormwater traps and from Lake Vesijärvi. Grab surface sediment samples were taken from Lake Vesijärvi at various distances (25–2,000 m) from four major stormwater drainage outlets and at 15 urban stormwater traps in areas with different degrees of urbanization. These samples were analysed for 16 PAHs and 28 PCBs with gas chromatography–mass spectrometry. The concentrations of pollutants in the lake sediments were elevated in the vicinity of the urban shore (∑PAH 3–16, ∑PCB up to 0.02–0.3 mg/kg dw) and decreased as a function of distance (∑PAH 0.1–2.5, ∑PCB 0.01–0.3 mg/kg dw at a distance of more than 500 m from the shore), whereas contamination levels in suburban areas were notably lower (∑PAH 0.1–3, ∑PCB?<?LOQ–0.03 mg/kg dw; did not decline with distance). Possible sources and pathways of contamination were also investigated. The majority of stormwater trap sediments contained predominantly asphalt-derived PAHs due to pulverized pavement. PAHs in lake sediments were of pyrogenic origin, including the combustion of gasoline, diesel and coal. Suggested pathways of lake contamination are urban runoff discharge, boat traffic and atmospheric deposition.     

A long-term monitoring study of chlorophyll,microbial contaminants,and pesticides in a coastal residential stormwater pond and its adjacent tidal creek

Stormwater ponds are commonly used in residential and commercial areas to control flooding. The accumulation of urban contaminants in stormwater ponds can lead to water-quality problems including nutrient enrichment, chemical contamination, and bacterial contamination. This study presents 5 years of monitoring data assessing water quality of a residential subdivision pond and adjacent tidal creek in coastal South Carolina, USA. The stormwater pond is eutrophic, as described by elevated concentrations of chlorophyll and phosphorus, and experiences periodic cyanobacterial blooms. A maximum monthly average chlorophyll concentration of 318.75 μg/L was measured in the stormwater pond and 227.63 μg/L in the tidal creek. Fecal coliform bacteria (FCB) levels were measured in both the pond and the tidal creek that exceeded health and safety standards for safe recreational use. A maximum monthly average FCB level of 1,247 CFU/100 mL was measured in the stormwater pond and 12,850 CFU/100 mL in the tidal creek. In addition, the presence of antibiotic resistant bacteria and pathogenic bacteria were detected. Low concentrations of herbicides (atrazine and 2,4-D), a fungicide (chlorothalonil), and insecticides (pyrethroids and imidacloprid) were measured. Seasonal trends were identified, with the winter months having the lowest concentrations of chlorophyll and FCB. Statistical differences between the stormwater pond and the tidal creek were also noted within seasons. The tidal creek had higher FCB levels than the stormwater pond in the spring and summer, whereas the stormwater pond had higher chlorophyll levels than the tidal creek in the summer and fall seasons. Chlorophyll and FCB levels in the stormwater pond were significantly correlated with monthly average temperature and total rainfall. Pesticide concentrations were also significantly correlated with temperature and rainfall. Pesticide concentrations in the stormwater pond were significantly correlated with pesticide concentrations in the adjacent tidal creek. Chlorophyll and FCB levels in the tidal creek, however, were not significantly correlated with levels in the pond. While stormwater ponds are beneficial in controlling flooding, they may pose environmental and human health risks due to biological and chemical contamination. Management to reduce residential runoff may improve water quality in coastal stormwater ponds and their adjacent estuarine ecosystems.     

Optimal Carbon Capture and Storage Policies

The IPCC recommends the use of carbon capture and sequestration (CCS) technologies in order to achieve the Kyoto environmental goals. This paper sheds light on this issue by assessing the optimal strategy regarding the long-term use of CCS technologies. The aim is to analyze the optimal CCS policy when the sequestration rate is endogenous, being therefore one specific tool of the environmental policy. We develop a simple growth model to identify the main driving forces that should determine the optimal CCS policy. We show that, under some conditions on the cost of extractions, CCS may be a long-term solution to curb carbon emissions. We also show that over time the social planner will choose to decrease the rate of capture and sequestration. We then derive the decentralized equilibrium outcome by considering the programs of the fossil resource-holder and of the representative consumer. Finally, we determine the optimal environmental policy, i.e. the carbon tax scheme, as well as the dynamics of the fossil fuel price needed to implement it.     

Upstream to downstream: stormwater quality in Mayagüez, Puerto Rico

The focus of this research was upon consequences of urban stormwater runoff entering two streams in Mayagüez, Puerto Rico. Mayagüez is the largest urban area of the western side of the island of Puerto Rico and provides an excellent point of reference to monitor the affects of urban development on water quality in a tropical climate. The two monitored streams were Quebrada del Oro and Cano Majagual. The research hypothesis asks, "Does stormwater runoff from urban development measurably affect the water quality of downstream receiving water by raising the conductivity, temperature, and flow quantity characteristics during storm events in comparison to upstream water quality?" In essence, the results for Quebrada del Oro agreed with the hypothesis of this project, while Cano Majagual produced results different from the hypothesis primarily due to the absence of non-urbanized land use for both upstream and downstream sections as well as the buffering capacity of a large wetland just upstream of the downstream instrument location of Cano Majagual. Both streams showed signs of stream impairment according to the temperature criteria (32°C or 90°F) set by the Junta de Calidad Ambiental and the US Environmental Protection Agency. Dissolved oxygen levels of the streams were severely affected by water temperature and oxygen-consuming matter within these stream systems, making dissolved oxygen and temperature important water quality parameters for tropical climates.     

Storm runoff quality and pollutant loading from commercial, residential, and industrial catchments in the tropic

Information on the pollution level and the influence of hydrologic regime on the stormwater pollutant loading in tropical urban areas are still scarce. More local data are still required because rainfall and runoff generation processes in tropical environment are very different from the temperate regions. This study investigated the extent of urban runoff pollution in residential, commercial, and industrial catchments in the south of Peninsular Malaysia. Stormwater samples and flow rate data were collected from 51 storm events. Samples were analyzed for total suspended solids, 5-day biochemical oxygen demand, chemical oxygen demand, oil and grease (O&G), nitrate nitrogen (NO₃-N), nitrite nitrogen, ammonia nitrogen, soluble reactive phosphorus, total phosphorus (TP), and zinc (Zn). It was found that the event mean concentrations (EMCs) of pollutants varied greatly between storm characteristics and land uses. The results revealed that site EMCs for residential catchment were lower than the published data but higher for the commercial and industrial catchments. All rainfall variables were negatively correlated with EMCs of most pollutants except for antecedent dry days (ADD). This study reinforced the earlier findings on the importance of ADD for causing greater EMC values with exceptions for O&G, NO₃-N, TP, and Zn. In contrast, the pollutant loadings are influenced primarily by rainfall depth, mean intensity, and max 5-min intensity in all the three catchments. Overall, ADD is an important variable in multiple linear regression models for predicting the EMC values in the tropical urban catchments.     

基于在线监测和SWMM模型的合流制排水体制系统化提升方案评估研究

合流制溢流污染严重威胁着下游受纳水体的水环境质量。为科学评估基于海绵城市理念的合流制排水体制系统化提升方案在解决老城区合流制溢流污染方面的效果,以嘉兴市老城区为研究对象,采用在线监测技术和SWMM数学模型相结合的方式,对嘉兴市老城区合流制排水体制系统化提升方案进行了全面评估。经在线监测评估发现,完成海绵城市改造后,嘉兴市老城区在研究期内的溢流频次减少为26次,小雨不会产生溢流;经SWMM模拟评估发现,完成海绵城市改造后,老城区合流制溢流口年溢流频次减少了132.2次。整体来看,基于海绵城市理念的合流制排水体制系统化提升方案突破了传统末端治理的局限,从雨污水产生、收集的全过程对合流制排水体制进行了系统化整治,对于提升全局水环境质量效果显著。     

Marine Reserve Design with Ocean Currents and Multiple Objectives

There is a growing tendency to consider marine reserves as a management and conservation tool. We investigate a spatial bio-economic model to determine fishery profits under conservation efforts. Rather than imposing a marine reserve on our model, we ask, “When and where should a marine reserve be implemented ?” For one-dimensional habitat, we determine conditions under which marine reserves emerge as a part of the optimal policy. Depending upon the size of the habitat, the optimal strategy is either to avoid fishing or to fish at maximum rate. The effect of ocean currents is analyzed through numerical simulations. We find that in the presence of strong currents, a marine reserve may become ineffective. If the currents are at low rate, a marine reserve could emerge as a variable management tool.     

Investigation of urban water quality using simulated rainfall in a medium size city of China

Road-deposited sediment (RDS) is an important environmental medium for impacting the characteristics of pollutants in stormwater runoff; it is of critical importance to investigate the water quality of urban environments. The paper develops a rainfall simulator as an important research tool to ensure homogeneity and reduce the large number of variables that are usually inherent to urban water quality research. The rainfall simulator was used to experiment runoff samples from typical residential and traffic areas in the Zhenjiang. The data show that land use is one of the major factors contributing to the difference in the pollutants concentration in the RDS. The maximum mean EMC for TN, TDN, TP, and TDP at residential area was 5.52, 3.07, 1.65, and 0.36 mg/L, respectively. The intense traffic area displayed the highest metal concentrations. Concentrations of runoff pollutants varied greatly with land use and storm characteristics. The correlation of pollutant concentrations with runoff times was another predominant phenomenon. Peaks in pollutants concentration occurred at 1 and 10 min during the whole storm event. A concentration peak that correlates with a peak in runoff flowrate correlates with rainfall intensity. The pollutant loadings (kilograms per hectare) in the Zhenjiang were 11.39 and 55.28 for COD, 8.42 and 57.48 for SS, 0.11 and 0.88 for TN, 0.02 and 0.14 for TP, 0.02 and 0.09 for Zn, and 0.01 and 0.04 for Pb. The higher rainfall contribute to the higher pollutant loading at the residential and intense traffic areas, as a result of the pollutant loadings direct dependence on rainfall intensity. The results confirmed that the rainfall simulator is a reliable tool for urban water quality research and can be used to simulate pollutant wash-off. These findings provide invaluable information for the development of appropriate management strategies to decrease nonpoint source contamination loading to the water environment in urban areas.     

Verification of a depth-integrated sample arm as a means to reduce solids stratification bias in urban stormwater sampling

A new water sample collection system was developed to improve representation of solids entrained in urban stormwater by integrating water-quality samples from the entire water column, rather than a single, fixed point. The depth-integrated sample arm (DISA) was better able to characterize suspended-sediment concentration and particle size distribution compared to fixed-point methods when tested in a controlled laboratory environment. Median suspended-sediment concentrations overestimated the actual concentration by 49 and 7% when sampling the water column at 3- and 4-points spaced vertically throughout the water column, respectively. Comparatively, sampling only at the bottom of the pipe, the fixed-point overestimated the actual concentration by 96%. The fixed-point sampler also showed a coarser particle size distribution compared to the DISA which was better able to reproduce the average distribution of particles in the water column over a range of hydraulic conditions. These results emphasize the need for a water sample collection system that integrates the entire water column, rather than a single, fixed point to properly characterize the concentration and distribution of particles entrained in stormwater pipe flow.     

Urban water resource management for sustainable environment planning using artificial intelligence techniques

In the current era, water is a significant resource for socio-economic growth and the protection of healthy environments. Properly controlled water resources are considered a vital part of development, which reduces poverty and equity. Conventional Water system Management maximizes the existing water flows available to satisfy all competing demands, including on-site water and groundwater. Therefore, Climatic change would intensify the specific challenges in water resource management by contributing to uncertainty. Sustainable water resources management is an essential process for ensuring the earth's life and the future. Nonlinear effects, stochastic dynamics, and hydraulic constraints are challenging in ecological planning for sustainable water development. In this paper, Adaptive Intelligent Dynamic Water Resource Planning (AIDWRP) has been proposed to sustain the urban areas' water environment. Here, an adaptive intelligent approach is a subset of the Artificial Intelligence (AI) technique in which environmental planning for sustainable water development has been modeled effectively. Artificial intelligence modeling improves water efficiency by transforming information into a leaner process, improving decision-making based on data-driven by combining numeric AI tools and human intellectual skills. In AIDWRP, Markov Decision Process (MDP) discusses the dynamic water resource management issue with annual use and released locational constraints that develop sensitivity-driven methods to optimize several efficient environmental planning and management policies. Consequently, there is a specific relief from the engagement of supply and demand for water resources, and substantial improvements in local economic efficiency have been simulated with numerical outcomes.     

Urban Water Supply Strategies for Hyderabad, India – Future Scenarios

To keep pace with population and economic growth, the city of Hyderabad, India, will need to identify and develop new supply sources almost continually. Increasing population growth rate, declining surface water resources, overexploitation of groundwater, deterioration of ground water quality and poor sewage treatment are the major water-related issues in Hyderabad. This paper reviews the current situation facing policy makers who need to come to terms with the problem of restricted water supply and increasing demand in an urban centre such as Hyderabad, India. The City Water Balance model developed in this study can be used to analyse different scenarios that include water conservation, urban wastewater reuse and improvement of distribution and conveyance efficiency. Water conservation programs, which include a 5% conveyance efficiency improvement, reusing 90 million cubic metres (MCM) of urban runoff and adoption of water harvesting by 0.5 million households together with recycling 120 MCM of wastewater recycling wastewater would be sufficient to meet the water demand by 2031, if the population grows at a rate of 2.5%.     

基于综合指数法的城市河流水环境质量排名探讨

依据城市河流水环境质量状况进行定期排名,是目前环境管理者为促进地表水环境质量改善的一种政策措施,采用正确的排名方法是保障排名结果是否合理的关键。研究选用综合污染指数法、水质类别法两种常用的评价方法,同时结合城市河流黑臭、浑浊等特点,筛选出pH、溶解氧、色度、化学需氧量、悬浮物、氨氮、总磷7项因子参与评价并对河南省辖内的城市河流进行排名。结果表明,选用的排名方法基本满足城市河流水环境质量排名的需求,具有广泛的应用价值。     

The impact of stormwater treatment areas and agricultural best management practices on water quality in the Everglades Protection Area

Half of the original Everglades system has been lost to drainage and development. What remains is included within the boundaries of the Everglades Protection Area (EPA), comprised of three Water Conservation Areas (WCAs) and Everglades National Park (Park). Inflows to the EPA contain elevated nutrient concentrations. Best management practices (BMPs) were implemented and six large wetlands called stormwater treatment areas (STAs) were constructed to improve water quality. We analyzed water quality in the WCAs and Park and performed an economic analysis of the STAs to remove nutrients from EPA inflows. In general, nutrient concentrations in all WCAs were higher during the pre-STA period than after the STAs became operational. In WCA2 and the Park, total phosphorus (TP) trends showed more negative slopes prior, as compared to after, the STAs became operational. These results suggest that BMPs lead to large initial decreases in nutrient export resulting in improved downstream water quality. A preliminary economic analysis shows that operation and management of the STAs are complicated and cost intensive. Comparing the cost of phosphorus (P) removal from water entering the EPA using BMPs and STAs may not currently be viable. BMPs prevent P from being applied to, or leaving from agricultural fields while STAs remove P from stormwater. We expect nutrient concentrations in water flowing into and out of the STAs to decline as both BMPs and STAs become more effective. We suggest an economic analysis of BMPs, STAs, and other potential approaches to determine the most cost-effective methods to reduce nutrient concentrations and related stressors affecting the Everglades.