Browsing by Subject "Drinking water"
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Item 2024-2033 Minnesota Drinking Water Action Plan Community Engagement Feedback Report(2024-03-01) Mahr, HeronThe Minnesota Department of Health (MDH) is developing a ten-year Drinking Water Action Plan that will guide Minnesota’s drinking water management from 2024-2033. The aim of this plan is to regulate safe and reliable drinking water supplies throughout Minnesota, with an emphasis on equitable access. The Drinking Water Action Plan is being created with input from drinking water professionals and consumers. This report details the feedback collected from consumers during community engagement sessions across the state. The objective of these sessions was to further water equity in Minnesota by gathering public opinions through survey questions and engaged dialogue.Item Effects of Aquaculture on Mine Pit Lakes near Chisolm, MN: Restoration of Twin City-South pit lake by fallowing and status of Fraser pit lake(University of Minnesota Duluth, 1995) Axler, Richard P; Yokom, Shane; Tikkanen, Craig A; Henneck, Jerald; McDonald, Michael ENet-pen salmonid aquaculture was carried out from 1988 to 1993 in the Twin City-South mine pit lake on the Mesabi Iron Range in northeastern Minnesota. A water quality controversy enveloped the aquaculture operation from its inception in 1988. In 1992 the Minnesota Pollution Control Agency mandated that all intensive aquaculture operations in the Twin City - South mine pit lake be terminated by July 1993 and that restoration to baseline (i.e. preaquaculture) conditions be demonstrated within three years. This "fallowing" has led to a rapid recovery to near baseline water quality conditions and an oligomesotrophic, i.e. unproductive, status. Water column improvement in regard to phosphorus and hypolimnetic oxygen concentrations has been particularly rapid. Although baseline conditions were not well defined for TC-S, the P budget for the lake in September and November 1994 was typical of reference pit lakes in the area. Oxygen concentrations in near-bottom water remained above 5 mg02/L in November 1994 even without artificial mixing or aeration during the 1994 growing season. Algal growth was low in 1993, as expected due to artificial mixing, and remained low in 1994 without any artificial mixing. Ammonium has been naturally converted to nitrate which is decreasing faster than expected and at a rate similar to its increase during intensive aquaculture. More rapid reductions in water column phosphorus and nitrogen might have been accomplished during the first summer by allowing the lower hypolimnion to become anoxic in order to promote denitrification and minimize sediment resuspension. The natural burial of sedimented aquaculture wastes due to high ambient rates of erosion of inorganic sediment from the basin walls has effectively minimized sediment nutrient transport to the overlying water column. Fallowing for several years appears to be an effective method for lake restoration of these pit lakes. Our data, and our analysis of the NPDES monitoring data, has shown no change in the water quality of Chisholm's drinking water source, the Fraser pit lake, attributable to aquaculture impacts. This, and no apparent change in the water quality of two nearby pit lakes, Grant and Ironworld in recent years, suggests little or no significant off-site migration of aquaculturally impacted water.Item Limnological Assessment of Mine Pit Lakes for Aquaculture Use(University of Minnesota Duluth, 1992) Axler, Richard P; Larsen, Christen; Tikkanen, Craig A; McDonald, Michael E; Host, George EThis study addresses water quality issues associated with current and future uses of mine pit lakes for intensive aquaculture. In current net pen aquaculture operations (Minnesota Aquafarms, Inc.), metabolic wastes and uneaten food are dispersed into the lakewater. Intensive aquaculture at Twin City-South and Sherman increased levels of phosphorus (P) and nitrogen (N) and reduced dissolved oxygen (DO) in the water column, and increased the deposition of organic matter to the bottom relative to their previous conditions and to unused mine pit lakes. Numerous trophic status indices suggest that TC-S and Sherman have shifted (or are shifting) from an oligotrophic state to a more eutrophic one. However, due to MAPs intensive aeration, and circulation, conditions necessary for algal blooms (typical of eutrophication) have been infrequent, due to light limitation from vertical mixing. Blooms of scum-forming bluegreen algae have never been observed.Item Limnological Re-Sampling of Chisolm Area Mine Pit Lakes with Reference to Former Aquaculture Impacts(University of Minnesota Duluth, 2000) Axler, Richard P; Henneck, JeraldLimnological surveys were conducted on two mine pit lakes (Twin City-South and Sherman) used for intensive netpen salmonid aquaculture over the period 1988-1995 and an adjacent pit lake (Fraser) used for drinking water by Chisholm, Minnesota. A water quality controversy had enveloped the aquaculture operation from its inception in 1988 to its bankruptcy in 1995. All intensive aquaculture operations in the Twin City-South pitlake were terminated in mid-1993 as mandated by the Minnesota Pollution Control Agency (MPCA) in order to determine if water quality could be returned to baseline values within three years (a condition of continued operation in the Sherman pit lake). The MPCA mandated that restoration to baseline (i.e. pre-aquaculture) conditions be demonstrated within three years. This "fallowing" led to a rapid recovery to near baseline water quality conditions and an oligomesotrophic, i.e. unproductive, status. Algal growth was low in 1993, due to light - limitation from artificial mixing, but remained low in 1994 without any management due to renewed P-limitation. Water column improvement in regard to phosphorus and hypolimnetic oxygen concentrations was particularly rapid. Although baseline conditions were not well defined for TC-S, the P budget for the lake after 18 months was typical of reference pit lakes in the area and oxygen concentrations in near-bottom water remained above 5 mg02/L without artificial mixing or aeration during the next growing season. Waste product ammonium was naturally nitrified to nitrate which decreased at a rate faster than expected, and similar to its increase during intensive aquaculture. More rapid reductions in water column phosphorus and nitrogen might have been accomplished during the first, summer by allowing the lower hypolimnion to become anoxic in order to promote denitrification and minimize sediment resuspension. Unfortunately these were precluded by the regulatory standards. The natural burial of sedimented aquaculture wastes due to high ambient rates of erosion of inorganic sediment from the basin walls effectively minimized sediment nutrient transport to the overlying water column and sediment oxygen demand.Item A Source to Tap Investigation of Minnesota's Groundwater Supplies Used for Drinking Water(2018-11) Galt, JohnGroundwater is often a desirable drinking water source because it is generally free of suspended solids and microbial pathogens and thus requires minimal, if any, treatment prior to distribution. Epidemiological studies have shown, however, that consumption of untreated groundwater increases risk of gastrointestinal illness. Previous work in Wisconsin, USA reported the occurrence of pathogenic viruses in groundwater supplies and resulting health impacts but bacterial pathogens were not investigated. In this study, a high-volume (300 – 1500 L) dead-end ultrafiltration sampling method was used to capture and recover microbes from 16 public groundwater systems throughout the State of Minnesota. The systems were sampled at the wellhead or source, after treatment if any (i.e., two systems did not treat or disinfect before distribution), and from one location in the distribution system. DNA was extracted from the microbes recovered in these samples and used as template for quantitative PCR analyses targeting 14 genes corresponding to pathogenic bacteria, one gene for a DNA virus, and the 16S rRNA gene as a marker for total bacteria. All samples were negative for the targeted genes from Campylobacter jejuni, Shigella spp., and Adenovirus; Escherichia coli-specific genes were only detected in water from a non-potable well with a documented history of contamination. Genes markers for two genera, Legionella and Mycobacteria, that include species that are opportunistic pathogens, were detected in four of the 16 public groundwater supplies, with Legionella levels decreasing in disinfected systems while Mycobacteria levels tended to increase. Raw water 16S rRNA gene concentrations ranged from 10^5 – 10^8 gene copies/L, decreased to background levels after disinfection, then rebounded at the tap in the majority of cities. There was no significant difference in 16S rRNA gene concentrations from source-to-tap in the two non-disinfecting cities. Raw water samples contained diverse and previously uncharacterized organisms as revealed by DNA sequencing analyses, and beta diversity analyses suggest that community composition is driven by source water and/or disinfection. The results from this study suggest that groundwaters supplying public water systems in Minnesota are largely free of enteric pathogens but may contain opportunistic pathogens.