Drop of Knowledge

All small water systems must create budgets and set rates for the communities they serve. For some systems, rates are set to prioritize maintaining the lowest rates possible rather than the physical and fiscal health of the system. Well-intentioned governing bodies may feel they are serving their community’s best interest in keeping rates low. However, if the rates are kept artificially low, this can do a disservice to the community. Chronically undercharging customers, without covering the true costs of maintaining and operating system infrastructure, will leave small and very small systems unable to conduct routine maintenance, manage their assets and reserve the capital necessary to invest in needed infrastructure upgrades.

Rates must recover the “true costs” of providing service, including all operational costs, and funding necessary reserve accounts and debt service, if applicable. Since water systems obtain most of their revenue from user charges, a rate structure’s fairness and adequacy are imperative to both the utility and its customers. Rates must be based on a strong, well-developed budget that includes all costs of service.

To determine the true cost of service for a system, you’ll need to account for:

Operating costs
Administrative costs
Debt service
Reserve account funding
Capital projects

Most utilities understand that operating and administrative costs must be recovered through customer rates. However, because there is an expectation the utility will provide uninterrupted service 24 hours a day, 365 days a year, there is no margin for failure. Therefore, the cash reserves a utility maintains are critical to its financial sustainability. Maintaining adequate reserve levels helps to ensure that the utility will have adequate funds available to meet its financial obligations in times of varying needs. It also provides a framework around which financial decisions can be made to determine when reserve balances are inadequate or excessive and what specific actions need to be taken to remedy the situation.

Utility reserve levels can be thought of as savings accounts. Reserve balances are funds that are set aside for a specific cash flow requirement, financial need, project, task, or legal covenant. Common reserve balances are established around the following four areas: operating reserve, capital improvement, emergency, and debt service reserve. These balances are maintained to meet short-term cash flow requirements and, at the same time, minimize the risk associated with meeting financial obligations and continued operational needs under adverse conditions.

Operating Reserve

Operating reserves are established to allow the utility to withstand short-term cash flow fluctuations. There can be a significant length of time between when a system provides a service and when a customer pays for that service. In addition, weather and seasonal demand patterns can affect a system’s cash flow. A 45-day operating reserve is a frequently used industry norm. Because of potential delays in collecting payment, many utilities attempt to keep an amount of cash equal to at least 45 days or one-eighth of their annual cash operation and maintenance expenses in an operating reserve to mitigate potential cash flow problems.

Capital Improvement Reserve 

A capital improvement reserve (CIP) (also called a repair and replacement reserve) is intended to be used to replace system assets that have become worn out or obsolete. Unlike the emergency reserve, the CIP reserve is intended to be used for planned replacements/upgrades. To initiate a CIP, a small water system will start with a list of assets including the remaining service life and theoretical replacement costs in today’s dollars. It then calculates the monthly and annual reserve that must be collected from each customer to fully capitalize the replacement cost of each asset. For many small and very small utilities, attempting to fully fund asset replacement would result in rates that are untenable. An amount of at least 20 percent of replacement costs can be the alternative target. Many loans and grants will fund a maximum of 80 percent of the project, leaving the utility to provide 20 percent in matching funds.

Emergency Reserve

In addition to operating reserves, emergency reserves are an important tool for financial sustainability. Emergency reserves are intended to help utilities deal with short-term emergencies that arise from time-to-time, such as main breaks or pump failures. The appropriate amount of emergency reserves will vary greatly with the size of the utilities and should depend on major infrastructure assets. An emergency reserve is intended to fund the immediate replacement or reconstruction of the system’s single most critical asset—an asset whose failure will result in an immediate water outage or threat to public safety.

Debt Service Reserve

Water utilities that have issued debt to pay for capital assets will often have required reserves that are specifically defined to meet the legal covenants of the debt. Normally, the debt service reserve represents an amount equal to one full annual loan payment (principal and interest) and can be accumulated to this level over a period of five to ten years.

Establishing an adequate operating revenue stream by creating a rate structure mindfully designed to recover the true costs of service requires examining historic financial documents and policies and evaluating current and future system requirements. From this, cost of service will be disclosed. From the cost of service, an appropriate rate structure can be developed.

*If you want to learn more about rate setting, please check out RCAP’s Rates guide.

There are four seasons winter, spring, summer, and fall. Some places may not experience them all, but we need to prepare for it all, as the last few years have taught us. For those lucky enough to see the leaves change from green to bright orange and deep reds, then drop to the ground to racked into piles for fun or so the grass doesn’t die. It is the sign that fall has come and winter will soon arrive.

Is your water or wastewater system prepared for winter storms, freezing temperatures, heavy snowfall, and the dangerous ice they can bring?

According to Environmental Protection Agency’s (EPA’s) Incident Action Checklist – Extreme Cold and Winter Storms (2015)1, cold weather can impact operations and cause problems. The effects of the cold weather may have a costly and lasting impact on utilities that may include, but are not limited to:

Broken pipes throughout the distribution system
Loss of power and communication lines
Limited access to facilities due to icy roads or debris
Reduced workforce due to unsafe travel conditions
Source water quality impacts due to increased amount of road salt in stormwater runoff
Potential flooding risk due to snowpack melt and ice jams
Potential surface water supply challenges as ice and frozen slush can black valves and restrict intakes

Now is the time that utilities should think about the resilience of their systems. EPA’s Incident Action Checklist – Extreme Cold and Winter Storms, lists ways utilities can prepare for, respond to and recover from the cold and winter storms.

Planning for extreme cold and winter storms can be as easy as monitoring for inclement weather. Being prepared for inclement weather can give utilities the time to gather extra equipment and supplies such as motors, chemicals, batteries, generators and fuel. It also gives them time to review and update the Emergency Response Plan (ERP). Double-check that the contact numbers are current for emergency response partners, such as the local Emergency Management Agency (EMA), Water/Wastewater Agency Response Network (WARN), and other mutual aid agencies. Taking the time to prepare also ensures that utilities can schedule and assign duties to personnel as needed. Another helpful hint is to make sure that emergency funds are set aside, in advance, just in case they are needed later. Do not wait until an emergency happens and there are not enough funds to take care of the issue.

Responding to extreme cold and winter storms begins by conducting a damage assessment of the utility and service area as soon as possible. The system should inspect the facility components for damage, such as leaks and line breaks. The service area should be checked for downed power lines and power outages. Contact your local EMA and state regulatory/primacy agency as soon as possible if your water quality or quantity is affected. Customers should also be notified immediately of any boil water notices or service disruptions.

Recovering from extreme cold and winter storms includes completing any repairs to return the utility to normal service, if necessary. Damage assessments should be reviewed to identify the effectiveness of storm preparation. Make a checklist of the following questions and jot down the answers to help with the process.

What worked and what didn’t work?
What needs to be improved?
Were there enough funds set aside?
Do you need to apply for state and/or federal funding?
Review the ERP and identify measures that can prevent damage in the future

These are just a few ways that a utility can prepare for, respond to and recover from extreme cold and winter storms. EPA’s Incident Action Checklist – Extreme Cold and Winter Storms goes into detail. It provides links to other good articles to have handy at this time of the year.

Take time to visit EPA’s website at https://www.epa.gov/system/files/documents/2021-10/incident-action-checklist-extremecold_508c-final.pdf to find out if your utility is ready for the winter.
1 Environmental Protection Agency. (2015, January). Incident Action Checklist – Extreme Cold and Winter Storms. EPA. Retrieved November 8, 2021, from https://www.epa.gov/.
Photograph Credit: © Evgen / Adobe Stock

Our Nation’s aging utility infrastructure is gaining notable attention. Multiple factors such as the ongoing COVID-19 pandemic, an aging workforce, and natural disasters occurring more often, the need for utilities to transition to digital workflows is evident and the time to act is now. Many rural utilities are still reliant on paper utility maps and field operation workflows.

These paper-based workflows often result in inefficiencies such as lack of access to paper maps, weathered/aged paper, redundant data entry processes, illegible handwriting, and an inability to meet regulatory requirements with accurate data entry. Additionally, the aging workforce has been accustomed to performing their role relying solely on paper workflows and can be resistant to digital workflows.

This reliance on paper maps and workflows makes it more difficult to overcome industry challenges and is costlier to operate, thus the need for digital transformation. The benefits of digital transformation are well-known—such as reducing operations costs and providing a better system of records. This results in smarter asset management decisions, attaining better regulatory compliance, and having more satisfied customers.

Geographical Information Services (GIS) Bridges the Transition from Paper to Digital Mapping

GIS in its simplest form, is a tool that incorporates geographical features with tabular data in order to map, analyze, and collaborate. The pivotal piece of this technology is geography – meaning that the data is spatial.  “Spatial” is defined as occupying a physical space on earth. Spatial data is usually accompanied by tabular data, known as attribute data. “Attribute data” is defined as additional information about a spatial feature.  An example of this would be a water valve. The actual location of the water valve is the spatial data. Additional data such as valve manufacturer, type of valve, the date the valve was installed, and the number of turns to open would make up the attribute data. It is the partnership of these two data types that enables GIS to be such an effective tool through spatial analysis. To obtain the spatial location of the water valve, GPS (Global Positioning System) technology is used in conjunction with GIS software.

The benefits of utilities utilizing GIS are numerous:

Knowing where infrastructure components are located
Baseline for Asset Management
Creating a singley, leads to improved records management
Increased operational efficiency among workforce; data access available 24 hours a day, seven days a week in a secure cloud-based solution
Improved proactive operations through efficient digital field operations and work order management procedures
Decreased reactive operations
Emergency preparedness and response
Meet regulatory compliance reporting
Transparency to the community and leaders
Theft reduction by more optimized water loss capability

The process can seem overwhelming for a rural community. Data collection is just the first step. There are stages in which digital transformation can be modeled once a utility decides to make the transition.

Smart Water Network Forum (SWAN), a global non-profit organization focused on advancing digital transformation in the water and wastewater industry provides the following Benefits of Digital Transformation for Water Utilities. (Source: https://www.swan-forum.com/blog/#Idrica-Digital-Transformation)

1- Data is translated into actionable information

The evolution of water meters, in relation to their data collection capabilities and communication systems, has led to unprecedented streams of information, which utility managers can use to make critical decisions proactively. However, today utilities only thoroughly analyze, on average, about 10 percent of the data they collect (2015 CIO Forum).

When conveniently used, Automated Meter Infrastructure (AMI) can help utilities take their digital transformation to the next level. Data collection is just the first step. For it to be useful, large data streams must be translated into actionable information via powerful analytical engines, allowing end-users to rapidly understand and act. This means that utilities should move from a data-siloed organization to a data-centric one, having full transparency and interoperability. According to Jaime Barba, CEO Idrica and global smart water expert, “data means nothing if it can’t be turned into information”.

2- Managers can make better decisions for a resilient future

As consumer behaviors change and climate change accelerates, there is a growing need for long-term planning to drive business decisions, but also for making accurate short-term decisions. Water utilities must build resilience by identifying potential impacts and developing adaptation plans. To build a sustainable water future it is necessary not only to have the adequate infrastructure but also to control in advance what is going to happen and why.

3- Utilities can move towards a customer-centric approach

Thanks to technological innovations related to water meters, utilities can now become proactive in customer management. The internet has enabled the transformation of many companies, provides enhanced detail of client information which, used properly, provides added value services to customers, reduces complaints, and can support industrial customers to optimize the use of water intake in their processes.

The benefits of digital transformation involve higher transparency with citizens, companies, and institutions, who will become key agents for a resource that is becoming increasingly scarce, and for which their direct involvement is required.

4- Benefits of digital transformation: ROI is increased

The digitalization of water resource management means savings at both the operational and investment levels. By automating previously manual processes, a smart water approach in organizations generates greater efficiencies at a lower cost. Any water utility, regardless of its phase in its digital transformation journey, can see increases in return on investment (ROI) from past investments and make the most of existing technology structures by implementing technological solutions to build a digital structure. The savings achieved can also be the basis for further investments in digitalization, thus making this process sustainable.

RCAP has a network of talent able to assist many communities to take the steps towards digital transformation.  Making an investment in rural America’s aging water and wastewater infrastructure provides an opportunity for communities to maintain sustainability and provide safe drinking water. Through GIS, sustainability becomes easier to achieve.

As a side note, we have just released our new GIS Guidebook, “The Role Mapping Serves for Your Small, Rural, or Tribal Utility”.

The aftermath of a storm can turn a community upside down. When stormwater and groundwater enter a sewer system, the inflow and infiltration (I&I) can cause overflows and sewage backups, increase wear and tear on the system, and produce enormous quantities of dirty water that strain the capacity of treatment facilities. In systems with significant I&I issues, even modest rain events can overwhelm collection and treatment systems. 

The Great Lakes Community Action Partnership (GLCAP) condition assessment team in Ohio brings clarity to rural communities in desperate need. 

The GLCAP Condition Assessment Team in Ohio helps small systems tackle the environmental challenges of summer downpours by helping them find the most critical problem areas of a system, strategically target repair and replacement dollars, and plan for future improvements. Since 2018, the GLCAP team has delivered condition assessment services to dozens of small systems. 

Through generous grants from the Ohio Water Development Authority, Rural Community Assistance Partnership (RCAP) acquired equipment to conduct condition assessment. This includes: a 3D LiDAR scanner for manhole inspections, acoustical testing equipment for rapid assessment of sewer mains, self-propelled and push cameras for sewer line inspection, advanced inspection management software, smoke testing equipment, sewer flow loggers, GPS equipment, rugged tablets, and associated safety gear. The equipment, in conjunction with the RCAP GIS team’s web and mobile data collection apps, makes for an exceptional field data collection and reporting program that can help small systems plan to lessen future environmental impacts.  

Conducting Condition Assessment 

Condition assessment evaluates the current state of a community’s water and wastewater infrastructure, helps estimate remaining useful life expectancy, and identifies the areas most in need of cleaning and repair. A typical visit might involve identifying potential sources of I&I utilizing flow tracking, smoke testing, and pipe inspections. This allows RCAP to provide insight into the origin of I&I, document problem areas, and recommend customized solutions. 

Manhole inspections, which are key for understanding the overall health of a sewer system, can be time consuming and generate a large of amount of data. Using the 3D LiDAR manhole scanner, RCAP improves efficiency in the field and collects higher quality data, with videos and 360-degree images offer communities an unparalleled view of their manhole structures. Standardized reporting methods and simple viewer programs ease the process of sorting and reviewing large quantities of inspection data. 

Valves, another key component of every water utility system, provide the first line of defense for controlling the impact of distribution system disruptions. Managing valves requires assessment of their condition, and a valve exercising plan supports cyclical maintenance. RCAP provides the labor, mechanical tools, mapping, data collection, and summary reporting crucial to the process. Summary reports show the impact of maintenance efforts, meet regulatory standards, and support decision making for replacement schedules. 

Tackling I & I Threats 

In Adelphi, Ohio, a village about 70 miles north of the Kentucky border, staff working on a stormwater master plan called on RCAP to investigate I&I in the village sewer system. “Adelphi was in a really tough financial position,” explained Ben Howard, RCAP Senior Rural Development Specialist. “The village has a collection-only sewer utility which sends flows to neighboring Laurelville for treatment, so any I&I is costly.” Adelphi pays for every gallon of wastewater treated by Laurelville. When I&I enters the sewer collection system, it increases the number of gallons that are delivered to Laurelville, which in turn increases Adelphi’s bill. 

The poor condition of the sewer system made it difficult to move forward with a stormwater plan, so the condition assessment team traveled to Adelphi to conduct some field investigation. They used the 3D LiDAR scanner tool and self-propelled crawler camera unit to scan and capture detailed images from inside manhole walls and sewer lines. They also used the acoustic rapid assessment tool to check for pipe blockages and aid in mapping the community sewer.  

“The acoustic rapid assessment tool  scores the condition of sewer lines based on the successful transmittance of sound from one manhole to the next,” Ben explained. “Most scored relatively well. Those that scored poorly were revisited near the center of town where there were signs of water backing up into manholes (surcharging). Then we used the crawler camera to see as far as we could.”  

RCAP was able to identify the problem area where water was backing up due to settled-out debris in the center part of town. The village will likely use a vacuum truck to remove the debris. RCAP also followed up with smoke testing to detect inflow from private property.  

Once RCAP staff know the full nature of the problem, they can work with a system’s consulting engineer to obtain a scope of work and estimate the cost to complete necessary repairs and improvements. By understanding what it costs to fix the problem, RCAP can help communities prioritize and develop a project timeline, seek board or council approval to pursue grants and subsidized loans for the project, and apply for funding. 

I&I take away capacity within collection systems and burden a wastewater treatment plant’s ability to efficiently process sewage. Stormwater issues abound in rural communities whose assets are chronically in danger of disrepair when municipal budgets run dry. But if a wastewater utility can eliminate excess sources of stormwater, it will reduce chemical, electrical and capital costs.  

By now, many of you have heard of the cyber attack on the water treatment facility in the City of Oldsmar, FL on February 5, 2021.  You can view the city’s press conference at https://www.youtube.com/watch?v=zx1wTh8G97Q.

The event consisted of unauthorized remote access to the utility’s supervisory control and data acquisition (SCADA) system where an intruder altered the amount of sodium hydroxide, raising the dosage by a factor of 100. This could have led to thousands of people suffering from sodium hydroxide poisoning, which includes: lung inflammation, throat swelling, burning of the esophagus and stomach, severe abdominal pain, vision loss, and low blood pressure, according to the University of Florida Health System. Fortunately, the water treatment operator on duty noticed the intrusion and corrected the issue before the change was able to take place. According to a release from the FBI:
“The cyber actors likely accessed the system by exploiting cybersecurity weaknesses including poor password security, and an outdated Windows 7 operating system to compromise software used to remotely manage water treatment. The actor also likely used the desktop sharing software TeamViewer to gain unauthorized access to the system.”
What would have happened if the operator was not on duty or did not notice the change? Would downstream monitoring and other alarms have detected this change before water quality and public health were impacted?

Has your system evaluated cybersecurity? Would you be able to prevent and/or respond to this type of attack?

Cybersecurity is one component of the risk and resiliency assessment (RRA) and emergency response planning (ERP) processes identified in America’s Water Infrastructure Act of 2018 (AWIA). The goal of the RRA and ERP process is to assess potential risks and then develop plans to respond. As shown in the recent case at the City of Oldsmar, water systems are vulnerable to cyber-attack. Awareness and planning are needed to protect against these vulnerabilities. RCAP, through its regional partners, has assisted a number of water and wastewater utilities in developing the EPA-compliant RRAs and ERPs required under AWIA.

One of the key components in addressing risk and resilience is training to raise awareness and identify potential actions to be taken to protect water systems. Under an EPA cooperative agreement, RCAP and its partner, American Water Works Association (AWWA), developed the AWIA Small Systems Certification Program.  This program consists of 5 eLearning modules. All are available free of charge to small water utilities at https://www.awwa.org/Professional-Development/Small-Systems#10954561-awia-small-systems-certificate-program.

Course 1: Introduction to Resiliency and America’s Water Infrastructure Act of 2018 – EL272 – As the introductory course in the Small Systems Resiliency Certificate Program, this course introduces the requirements for water utilities established by America’s Water Infrastructure Act of 2018 (AWIA) and defines how the certificate program can help small systems to meet those requirements.

Course 2: Operational Measures for Resiliency – EL273 – The second course in the Small Systems Resiliency Certificate Program, the course content covers each aspect of security, field assessments of critical assets, and operational resiliency.

Course 3: How to Develop a Risk and Resilience Assessment – EL274 – As the third course in the Small Systems Resiliency Certificate Program, the course guides small systems through developing a Risk and Resiliency Assessment (RRA) with an RCAP/AWWA worksheet designed for small utilities.

Course 4: How to Develop a Small System Emergency Response Plan – EL275 – As the fourth course in the Small Systems Resiliency Certificate Program, the course guides small systems through developing an Emergency Response Plan (ERP) with the EPA ERP template.

Course 5: Cybersecurity for Water Systems – EL276 – The fifth course in the Small Systems Resiliency Certificate program explains the importance of cybersecurity best practices for critical infrastructure and demonstrates how AWWA’s water sector cybersecurity risk management guidance and tool can help a utility identify gaps in current cybersecurity practices.

The cybersecurity module is currently geared towards water systems of all sizes but is being modified by RCAP and AWWA to better address the needs of small communities. A draft of the revised module should be available for release by the end of March.

While the eLearning modules provide the essential knowledge for addressing AWIA requirements and can be used by some facilities in developing plans, additional training and technical assistance is often needed to help small communities conduct these assessments and develop complimentary ERPs.  RCAP can provide this training and technical assistance. When needed, RCAP and its partners can also provide more in-depth cybersecurity training and analysis. The process consists of assessing the current use of technology; evaluating the controls and practices to identify, protect, and detect threats to their cyber systems; and where to go for more support.

For more information, contact Jeff Oxenford, RCAP Director of Training and Technical Services at [email protected] or (720) 353-4242.

Editor’s note: McElmurry is a contributing author for Drop of Knowledge and leader of a collaborative research project exploring the intersection of drinking water and public health. RCAP is working with the researchers on this project to provide the rural perspective. RCAP has provided feedback on the researchers’ survey instrument.

Water systems and public health systems grew up together and are interdependent in complex, and not always clearly, visible ways.  A research program, Water, Health Infrastructure Resilience and Learning (WHIRL) funded by the National Science Foundation is exploring these interdependencies and will soon be distributing a survey to both water and public health professionals.

In 1914, the United States Public Health Service (PHS) adopted the first drinking water guidelines targeting microbial (coliform bacteria) and chemical (arsenic) contaminants (US Treasury, 1914). This led to the advent of centralized municipal drinking water systems that are credited with reducing nearly half of the total mortality, and three-quarters of the infant mortality, in major U.S. cities during the first half of the twentieth century (Cutler & Miller, 2005).  In the 100+ years since the development of drinking water guidelines, these interdependent systems have developed through separate federal regulatory agencies (i.e., Environmental Protection Agency, Department of Health and Human Services), management frameworks, and even different professional and educational disciplines. As a result, many drinking water and public health systems are now highly disconnected (Levitt & March, 1988).

Disconnects between water and health systems are confounded by practices put in place after September 11, 2001. Many post 9/11 practices were designed to isolate water systems and restrict the flow of information, with the goal of protecting systems and facilities from potential terrorist attacks. However, these restrictions had the unintended consequence of making it more difficult to share information with key stakeholders, such as public health officials and the public.  This may have contributed to a public that is largely not engaged, unaware and uninformed about how drinking water systems work and the importance of investing in their upkeep (Bipartisan Policy Center, 2017).

Both highly visible / public and “under the radar” events emphasize the growing need for a stronger connection between public health and drinking water. Day-to-day events (e.g., faulty, aging infrastructure that affects water quality) and disruptive weather (e.g., hurricanes, floods and droughts) that can lead to infectious disease outbreaks or human-induced disasters (e.g., chemical spills, contamination) are failures that can shut down drinking water services and have substantial adverse impacts on public health. Risks, hazards, and disruptions, even minor events that often go unnoticed, may illuminate interdependencies between drinking water and public health systems. If these interdependencies are critical, identifying these connections and strengthening them may enhance resilience.This is particularly true during periods immediately following events, when there are opportunities to learn, change and enhance system resilience (Sitkin, 1992; Turner 1976; May, 1992; Birkland, 2004).

In 2018, the National Science Foundation (NSF) funded a 4-year study to examine how drinking water and public health systems interact, with a focus on reducing risks of future disasters and enhancing the resilience of these two critical infrastructure systems. The project, entitled Water and Health Infrastructure Resilience and Learning (WHIRL), also aims to understand how these systems learn about and adapt to changes and how the public engages with these systems. The research is a collaboration between academics from Wayne State University, the University of Michigan, and Indiana University and the American Water Works Association, the Water Research Foundation, the Association of State Drinking Water Administrators, the Rural Community Assistance Partnership (RCAP), and the National Association of County and City Health Officials.

In collaboration with these partners, the WHIRL team has developed a survey questionnaire that will be distributed to water and health professionals over the coming weeks to collect information about how water systems and public health systems interact, both formally and informally. The survey includes questions about information exchange, communication, routine and non-routine interactions and the ways these groups learn from crises and disasters among other issues. The goal is to generate understanding about how drinking water-related hazards and disruptions unfold in ways that affect both drinking water and public health systems that can help in the construction of tools to detect undesirable events. In addition, the project will create new capacity to learn from the disruptions that will inevitably occur.

The WHIRL survey is available here.  Broad participation from the water community is necessary to insure representative and reliable results. Summaries of results from this survey will be reported at conferences and in future editions of the Drop of Knowledge.

References:

Bipartisan Policy Center (2017). Defeating Terrorists, Not Terrorism: Assessing U.S. Counterterrorism Policy from 9/11 to ISIS. Task force on terrorism and Ideology. Washington, D.C., Bipartisan Policy Center.
Birkland, T. A. (2004). Learning and policy improvement after disaster: The case of aviation security. American Behavioral Scientist, 48(3), 341-364.
Cutler, D., & Miller, G. (2005). The role of public health improvements in health advances: The twentieth-century United States. Demography, 42(1), 1-22. doi: 10.1353/dem.2005.0002
Levitt, B., & March, J. G. (1988). Organizational learning. Annual Review of Sociology, 14(1), 319-338.
Sitkin, S. B. (1992). Learning through failure: The strategy of small losses. Research in Organizational Behavior, 14, 231-266.
Turner, B. A. (1976). The organizational and inter-organizational development of disasters. Administrative Science Quarterly, 21(3), 378-397.
U.S. Treasury Department. (1914).
The bacteriological standard for drinking water. Public Health Rep. 29:2959-2966.