Bowland Lake, an acidified lake (pH 4.8–5.2), was treated with calcite (CaCO3) in 1983. Neutralization allowed for successful reproduction by reintroduced lake trout (Salvelinus namaycush). Mortality of lake trout embryos and juveniles in field toxicity tests decreased from 52–99% preneutralization to 0–30% postneutralization. The resident yellow perch (Perca flavescens) appeared unaffected by the chemical treatment. Both inter- and intra-specific competition were evident in the growth and body condition of perch and stocked lake trout in the years after neutralization. Springtime acid episodes continued to occur in the nearshore areas after the lake was neutralized, but no adverse effects on fish species were detected.

After neutralization of Bowland Lake, a clear oligotrophic acidified lake, with CaCO3 in August 1983, the whole-lake pH and alkalinity increased from 4.9 and −6 μeq∙L−1 to 6.7 and 89 μeq∙L−1, respectively. Total whole-lake Al decreased gradually from 130 to 30 μg∙L−1, Mn decreased from 80 to 28 μg∙L−1 and the lake became less transparent as dissolved organic carbon (DOC) increased and Secchi depth decreased. Metals other than Al and Mn remained low and did not respond to neutralization. Between August 1983 and March 1986, about 40% of the added alkalinity of Bowland Lake was lost. Decreases of whole-lake pH following snowmelt occurred prior to but not after neutralization. Neutralization of lake water did not prevent acidic melt water from forming a distinctive acidic zone < 1 m thick beneath the ice. The melt layer was more acidic than lake water, it was colder and therefore less dense, it usually contained higher Al, and it was dilute with lower conductivity and Ca. intra-site variation was probably due to variable volumes of melt water received. A snowmelt model based on daily air temperature and precipitation predicted intermittent recharge of groundwater reservoirs during snowmelt. However, runoff was continually observed nearshore under ice suggesting that groundwater reservoirs continued to discharge after recharge ended or that the residence time of melt waters in the littoral zone was relatively long.

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