Domestic supply wells meet much of the world’s potable water demand. These wells tend to fail as regional groundwater levels decline from intensive agricultural groundwater use, especially during drought when additional pumping occurs. This work examines approaches for addressing impacts on domestic wells in much of the San Joaquin Valley in California, USA, where groundwater management is now required. Mitigation actions and their costs are considered to allow continued well operations as groundwater levels decline to target levels specified in groundwater management plans. The estimated total mitigation cost for groundwater-level declines to the planned management targets ranges from $42 to $96 million depending upon well retirement age. If groundwater levels decline further to defined limits below the management targets allowed during drought, costs increase by $78 to $153 million. There will likely be competition for specialized labor to implement the mitigation actions since agricultural wells will also be affected. Unless current groundwater management plans become more stringent and specify shallower groundwater depth targets, proactive mitigation should be considered for the most vulnerable areas to prevent impacts from growing beyond the capacity for timely mitigation and to avoid widespread failure of rural domestic water supplies. The cost of mitigation for impacted wells is estimated to be less than 2% of the benefit to agriculture from being allowed to pump groundwater in excess of management targets during a multiyear drought.

Groundwater management planning requires balancing the interests of different stakeholder groups because (1) water supply development causes changes to groundwater systems that include declines in groundwater levels and (2) benefits and costs from pumping the common‐pool resource often do not occur such that they are shared proportionate to use. Quantifying impacts from declining groundwater levels among user groups can be useful for evaluating management strategies. In California, considering impacts to supply well operations is proving important for acceptance of management plans that have been required by law. A case study is presented to illustrate the types of results that may contribute to the planning process. The results indicate that significant differences in impact may occur between groundwater pumpers. Suggestions are provided for using this information to mitigate impacts to the most vulnerable stakeholders.

Formal policy analysis can aid resource management where groundwater is used intensively. Approaches for developing equitable and effective pumping allocations for drought are evaluated in the context of the 2012–2016 drought in Tulare County, California, USA. Potential economic impacts of policy alternatives on two user groups with conflicting interests are considered. Tradeoffs between losses of agricultural profit and response costs for domestic wells that run dry are estimated for various maximum groundwater depth policies. A welfare maximizing approach for identifying policies that limit depth to groundwater is evaluated and found to be ineffective because agricultural opportunity costs are much larger than domestic well costs. Adding a fee for additional drought groundwater pumping is proposed as a more impactful and balanced management policy approach. For the case study presented, a fee range of $300 to $600/acre-foot ($300–$600/1,233 m 3 ) yielded an effective groundwater management policy for reducing domestic well impacts from drought and balancing agricultural impacts of drought with the need to replenish additional drought pumping in wetter years. Recent management policies enacted in the study area agree with this finding. These results may provide a useful perspective for analytically examining and developing groundwater management policies near the study area and elsewhere.

A hydro-economic approach for planning on-farm managed aquifer recharge is developed and demonstrated for two contiguous sub-basins in California's Central Valley, USA. The amount and timing of water potentially available for recharge is based on a reoperation study for a nearby surface-water reservoir. Privately owned cropland is intermittently used for recharge with payments to landowners that compensate for perceived risks to crop health and productivity. Using all cropland in the study area would have recharged approximately 4.8km(3) (3,900 thousand acre-feet) over the 20-year analysis period. Limits to recharge effectiveness are expected from (1) temporal variability in recharge water availability, (2) variations in infiltration rate and few high-infiltration recharge sites in the study area, and (3) recharged water escaping from the study area groundwater system to surface water and adjacent sub-basins. Depending on crop tolerance to ponding depth, these limitations might be reduced by (1) raising berm heights on higher-infiltration-rate croplands and (2) creating dedicated recharge facilities over high-infiltration-rate sites.

The effects of groundwater depletion may impose costs on many people that rely upon the resource. Such costs are not borne entirely by the high-volume pumpers that largely create the problematic conditions. Ideally, sustainable groundwater management should include addressing economic externalities and social equity, although information quantifying these concerns is often unavailable. This work estimates impacts to domestic water well owners from groundwater overdraft caused mostly by pumping deeper agricultural wells. A study is presented for Tulare County in the southern Central Valley of California, USA, where many interruptions in domestic well supplies occurred during a recent drought. The case has unusually well-documented conditions and data available for analysis. A method is developed to model supply interruptions and estimate costs for maintaining domestic water well supplies that are impacted by declining groundwater levels. The analysis is performed in the context of planning for sustainable groundwater management and suggestions for managing the economic externality are made. This work may provide a basis for evaluating the economic impacts on well owners from over-pumping in basins outside the study area where less data may be available.

Contaminant migration through inactive supply wells can negatively affect groundwater quality and the combined effects from groups of such wells may cause greater impacts. Because the number of wells in many basins is often large and the geographic areas involved can be vast, approaches are needed to estimate potential impacts and focus limited resources for investigation and corrective measures on the most important areas. One possibility is to evaluate the geographic distribution of well-screen depths relative to hydrogeologic conditions and assess where contaminant migration through wells may be impacting groundwater quality. This approach is demonstrated for a geographically extensive area in the southern Central Valley of California, USA. The conditions that lead to wells acting as conduits for contaminant migration are evaluated and areas where the problem likely occurs are identified. Although only a small fraction of all wells appear to act as conduits, potential impacts may be significant considering needs to control nonpoint-source pollution and improve drinking water quality for rural residents. Addressing a limited number of areas where contaminant migration rates are expected to be high may cost-effectively accomplish the most beneficial groundwater quality protection and improvement. While this work focuses on a specific region, the results indicate that impacts from groups of wells may occur in other areas with similar conditions. Analyses similar to that demonstrated here may guide efficient investigation and corrective action in such areas with benefits occurring for groundwater quality. Potential benefits may justify expenditures to develop the necessary data for performing the analyses.

Water supply wells can act as conduits for vertical flow and contaminant migration between water-bearing strata under common hydrogeologic and well construction conditions. While recognized by some for decades, there is little published data on the magnitude of flows and extent of resulting water quality impacts. Consequently, the issue may not be acknowledged widely enough and the need for better management persists. This is especially true for unconsolidated alluvial groundwater basins that are hydrologically stressed by agricultural activities. Theoretical and practical considerations indicate that significant water volumes can migrate vertically through wells. The flow is often downward, with shallow groundwater, usually poorer in quality, migrating through conduit wells to degrade deeper water quality. Field data from locations in California, USA, are presented in combination with modeling results to illustrate both the prevalence of conditions conducive to intraborehole flow and the resulting impacts to water quality. Suggestions for management of planned wells include better enforcement of current regulations and more detailed consideration of hydrogeologic conditions during design and installation. A potentially greater management challenge is presented by the large number of existing wells. Monitoring for evidence of conduit flow and solute transport in areas of high well density is recommended to identify wells that pose greater risks to water quality. Conduit wells that are discovered may be addressed through approaches that include structural modification and changes in operations.

An evaluation of pumping alternatives was performed in support of remedial action planning for a groundwater cleanup in California. The cleanup was to remedy impacts to a water supply wellfield by a groundwater plume. The evaluation focused on assessing operational requirements for the wellfield in order to (1) accomplish groundwater plume containment and (2) meet water supply demands after treatment. Given the range of interests and perspectives represented by the various project stakeholders, it was clear that additional assessment would likely be required before the final details of the remedial action were agreed upon. Use of a streamlined and rapidly reproducible approach was key to reducing time requirements and successful evaluation of the pumping alternatives. This paper summarizes the results of applying mixed-integer linear programming techniques to the evaluation of pumping alternatives. The benefits and potential pitfalls of using optimization techniques in consulting work are also highlighted.

Mitraphylline is isolated from the hark of Mitragyna rubrostipulaceae and is separated from beta-sitosterol, quinovic acid and nitrogenous bases comprising alkaloidal congeners. The molecular formula, C21H26O4N2, the presence of one methoxyl group - probably incorporated in a methoxycarbonyl group, and the absence of rnethyl-imino groups are confirmed; but the alleged presence of an olefinic linkage is refuted and, contrary to previous statements, it is found that the alkaloid may be induced to yield a mono-acetyl derivative. The ultra-violet and infra-red absorption spectra of mitraphylline are measured and are shown to be consistent with an oxindole structure. Distillation of mitraphylline from zinc dust in vacuo is found to yield degradation products of considerable significance. In particular, isoquinoline is isolated from the basic fraction while a neutral product, C10H9ON, is identified as either 3-ethylidene-or 3-vinyl-oxindole since it affords 3-ethyloxindole on hydrogenation. Mitraphylline may therefore be regarded as a derivative of N-(beta-3-oxindolylethyl)perhydroisoquin-oline, in which only the suspected methoxycarbonyl group and one unidentified oxygen atom remain to be located. Moreover, the neutral compound, C10H9ON, is now shown to he identical with the methylcarbostyril which Barger, Dyer and Sargent had obtained from the related alkaloid, rhynchophylline. In the light of these facts the evidence reviewed shows that in the Mitragyna bases an oxindole group of alkaloids co-exists with the beta-carboline type indicated by previous investigations. Synthetic work described includes the syntheses of 1:7-dimethyltryptophan and of 9-methyl-, 1;9-dimethyl-, 2:9-dimethyl- and 1:2:9-trimethyl-beta-carbolines. The apparatus used for the extraction of the bark and a device for the chromatography of colourless substances are described.