Journal Articles

This project aims to evaluate the potential of reused grey water in concrete and mortar in order to preserve fresh water for drinking purposes. Using both Treated Grey Water and Raw Grey Water (TGW and RGW, respectively) led to a significant increase in the initial setting time and a decrease in the concrete slump value. In addition, there was no effect on mortar soundness properties. The mortar and concrete compressive strength results obtained at 7 days moist curing time showed a significant increase. Mortar and concrete mixes using TGW cast at curing times of 28, 120, and 200 days led to no significant effects on compressive strength. On the contrary, the RGW achieved slightly negative impact on compressive strength at all curing ages. According to the American Society for Testing and Materials (ASTM C109), TGW and RGW are suitable for mortar and concrete production. Furthermore, these results are in harmony with established requirements for ASTM C94.

In conclusion, TGW and RGW are potential alternatives for fresh water in the concrete manufacturing industry.

In collaboration with city, county, and academic institutions can open new opportunities to secure new water resources. Green infrastructure is critical to reducing the demand on potable supplies, explain authors Susanna Eden at the University of Arizona Water Resources Research Center and at the Pima County Regional Flood Control District.

Water harvesting has been used in the Tucson, Arizona region since prehistoric times and is now in resurgence. Within the past 30 years, Tucson has become a leader in desert rainwater and stormwater capture to build resilience and address growing concerns about water scarcity. Beginning with grassroots efforts focused on collective impacts of individual and neighborhood actions, a new attitude toward rainfall as a resource is flourishing. Local programs encourage citizen participation and support small-scale, distributed infrastructure, with an emphasis on retrofitting properties and roadways, while a large-scale stormwater harvesting project collects enough water to irrigate a regional sports park.

The interconnectivities of groundwater to food, energy, and the climate are addressed to various degrees at the state level. Groundwater governance in the United States is decentralized, resulting in considerable variations in state practices. This article, published in Jurimetrics and written by Sharon B. Megdal and Jacob Petersen-Perlman, reports on two state-level surveys and three regional case studies conducted to better understand groundwater governance strategies and practices. The article also relates the results of these research efforts to food, energy, and climate. The analysis points to the importance of identifying best practices for addressing nexus challenges for groundwater.

Citation: Sharon B. Megdal & Jacob D. Petersen-Perlman, Decentralized Groundwater Governance and Water Nexus Implications in the United States, 59 JURIMETRICS J. 99-119 (2018).

Groundwater, the "invisible water," is difficult to assess, manage and govern for many reasons, mostly due to the unknown quantities of the resource. Political boundaries dividing groundwater aquifers make assessment even more challenging. This article focuses on lessons learned from the hydrologic assessment of the Transboundary San Pedro and Santa Cruz aqufiers. The authors conducted the work in two phases: (1) laying the groundwork and (2) implementation. The "laying the groundwork" phase consisted of binational meetings with stakeholders and key actors (agencies and individuals), and the development of an understanding of the physical, institutional, historical, and socio-political context. This led to the signing of the binational Transboundary Aquifer Assessment Program (TAAP) agreement in 2009 and detailed the process for cooperation and coordination in the assessment of shared aquifers. The implementation phase began with an agreement to proceed with the study of four "focus" aquifers (Santa Cruz, San Pedro, Mesilla (Conejos-Medanos in Mexico), and Hueco Bolson (Bolson del Hueco in Mexico) and development of associated technical teams. Though a brief discussion of the lessons learned from the physical science portion of the study is included, the results have been described and published elsewhere. The bulk of the paper instead focuses on the findings and lessons learned from the integration of social-science perspectives into a largely physical-science based program, since there is a growing recognition of the need for this type of approach especially in the management and assessment of transboundary aquifers.

Groundwater is increasingly important for meeting water demand across the United States (U.S.). Forward thinking governance and effective management are necessary for its sustainable use. In the U.S., state governments are primarily responsible for groundwater governance (i.e., making laws, policies, and regulations) and management (i.e., implementation of laws, policies, and regulations). This decentralized system results in diverse strategies and practices. We surveyed a water quality professional from each state to better understand commonalities and differences across states. These professionals identify a wide assortment of groundwater issues and concerns, including quality and quantity impairment, staffing and budget issues, private well vulnerability, and overdraft. Respondents indicate contamination problems from natural and anthropogenic sources. Most respondents report that their states have significantly changed groundwater quality policy during the past 30 years. While most states have multiple funding sources for water quality programs, program budgets have decreased in the last decade, thereby hindering effective implementation of new policies. Over half of respondents indicate that water-quality/water-level monitoring and increased groundwater pumping will require more attention over the next decade. Several respondents anticipate groundwater regulation changes in the next five years. We discuss how our findings align with current groundwater uses in the U.S.

Many consider gravity-flow irrigation inefficient and deride its use. Yet, there are cases where gravity-flow irrigation can play an important role in highly productive and profitable agriculture. This perspective article reviews the literature on the profitability and efficiency of gravity systems. It then reviews the history of water management in Yuma, Arizona, which is one of the most productive agricultural areas in the United States. Through extensive changes in irrigation technologies, changes in production practices, and investments in irrigation infrastructure, Yuma agriculture dramatically shifted from perennial and summer-centric crop production to winter-centric, multi-crop systems that are focused on high-value vegetable crops. These innovations have led to improvement in various irrigation efficiency measures and overall water conservation. Return flows from the system, which were once characterized as an indicator of inefficiency, provide valuable environmental services to the Colorado River Delta ecosystem. Yuma’s history illustrates that innovative gravity-flow systems can be productive and water-conserving, and that a system-wide perspective is critical in evaluating irrigation systems.

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Membership on the Transboundary Aquifer Assessment Program (TAAP) team continues to be gratifying. The late 2016 publication of the Binational Study of the Transboundary San Pedro Aquifer by the International Boundary and Water Commission marked a milestone. This study is noteworthy in that it is a first-ever binationally prepared, fully bilingual aquifer assessment along the border shared by the United States and Mexico, and because it was subject to peer review on both sides of the border. 

One of the more interesting and sometimes debated elements of Arizona’s Groundwater Storage and Recovery Program is the Groundwater Savings Program (GSP). The program was developed when Arizona was struggling to utilize its Central Arizona Project (CAP) water. Agricultural water users rejected the use of CAP water due to its high cost relative to groundwater. Yet, the higher the ratio of agricultural to municipal use, the lower were Arizona’s CAP repayment obligations to the federal government, according to the formula used at the time. By the early 1990s, it was clear that both the municipal and agricultural sectors would benefit from a program designed to increase agricultural use of CAP water. 

A pilot grey water treatment system and collection network were designed, installed, and operated in Jordan Valley using natural filtration materials. Grey water from showers and washing sinks was collected from four houses. In order to evaluate the performance of multi-layer filter (MLF) ability to remove the pollutants from the collected grey water, the quality of treated and untreated grey water was examined and the suitability of treated grey water for irrigation was assessed. The results revealed that the efficiency removal of organic material before UV disinfection stage for BOD5, COD, and TSS was about 88.6, 83, and 92.2%, respectively. The efficiency removal rates for nutrients by MLF were a bit low as 32.5% of total phosphorous and 19.8% of total nitrogen were removed, whereas the removal efficiency of heavy metals Zn, Fe, and Ba were 94.8, 81.2, and 15.7%, respectively. The results showed that the pilot plant has efficiently reduced the coliform organisms, thermo-tolerance coli count, and Escherichia coli by more than 99.9% removal efficiency by the double-filter stage and 100% after disinfection stage. The current MLF system has the transferability potential to other locations of the developing world.

This project aims to evaluate the potential of reused grey water in concrete and mortar in order to preserve fresh water for drinking purposes. Using both Treated Grey Water and Raw Grey Water (TGW and RGW, respectively) led to a significant increase in the initial setting time and a decrease in the concrete slump value. In addition, there was no effect on mortar soundness properties. The mortar and concrete compressive strength results obtained at 7 days moist curing time showed a significant increase. Mortar and concrete mixes using TGW cast at curing times of 28, 120, and 200 days led to no significant effects on compressive strength. On the contrary, the RGW achieved slightly negative impact on compressive strength at all curing ages. According to the American Society for Testing and Materials (ASTM C109), TGW and RGW are suitable for mortar and concrete production. Furthermore, these results are in harmony with established requirements for ASTM C94.