The Trojan Y Chromosome strategy (TYC) is a promising eradication method for biological control of nonnative species. The strategy works by manipulating the sex ratio of a population through the introduction of supermales that guarantee male offspring. In the current study, we compare the TYC method with a pure harvesting strategy. We also analyze a hybrid harvesting model that mirrors the TYC strategy. The dynamic analysis leads to results on stability of solutions and bifurcations of the model. Several conclusions about the different strategies are established via optimal control methods. In particular, the results affirm that either a pure harvesting or hybrid strategy may work better than the TYC method at controlling a nonnative species population. Recommendations for resource managers• Where harvesting is feasible, it is as effective if not more effective than the classical TYC method. Therein managers may attempt harvesting female fish while stocking males or harvesting both male and female fishes.• Managers may attempt linear harvesting, saturating density-dependent harvesting, and unbounded density-dependent harvesting. Linear harvesting is seen to be the most effective.• We caution against the outright use of harvesting due to various density-dependent effects that may arise. To this end hybrid models that involve a combination of harvesting and TYC-type methods might be a better strategy.• One may also use harvesting as a tool in mesocosm settings to predict the efficacy of the TYC strategy in the wild.

Lusaka, Zambia, is a rapidly growing city located on a vulnerable karstic dolomite aquifer that provides most of the city's drinking water. Over 65% of residents live in peri‐urban communities with inadequate sanitation leading to widespread groundwater contamination and the spread of waterborne diseases such as cholera. To fill the water service gap, Water Trusts were created: public/private partnerships designed to provide clean water to peri‐urban community residents. Water Trusts extract groundwater via boreholes, treat it with chlorine, and distribute it to residents via public kiosks. We investigated the efficacy of drinking water provision to residents in six of Lusaka's peri‐urban communities with Water Trusts. Water samples were collected from Water Trust boreholes and kiosks, privately owned boreholes, and shallow wells during four sampling efforts. To assess potential risk to human health, water samples were analyzed for Escherichia coli ( E. coli ) and nitrate. Shallow wells were significantly more contaminated with E. coli than Water Trust boreholes, kiosks, and private boreholes (Tukey‐adjusted p values of 9.9 × 10 −6 ). Shallow wells and private boreholes had significantly higher nitrate‐N concentrations (mean of 29.6 mg/L) than the Water Trust boreholes and kiosks (mean of 8.8 mg/L) ( p value = 1.1 × 10 −4 ). In 2016, a questionnaire was distributed to Water Trust managers to assess their ability to meet demands. In the six communities studied, Water Trusts served only about 60% of their residents. Water Trusts provide a much safer alternative to shallow wells with respect to nitrate and E. coli , but they struggle to keep pace with growing demand.

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