Agenda - Council Work Session - 02/23/2021

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Groundwater recharge reaches the water table (i.e., quaternary or surficial aquifer) at a fast rate through sandy geologic deposits. The location of the watershed within the Anoka sand plain creates the potential for high infiltration rates throughout the LRRWMO and associated groundwater contamination from pollutants carried from the ground surface. The sensitivity of the surficial aquifer to contamination was assessed as part of the MDNR's 1993 Regional Hydrogeologic Assessment (RHA) and is presented in Figure 2-6. Management of stormwater runoff in the watershed must consider and the ease with which contaminants will enter the system and be transported through it. Residents within the LRRWMO obtain their drinking water from municipal groundwater wells and private domestic wells. Approximately 50% of the cities of Andover and Ramsey, and all of Anoka, are served by municipal systems. Most private wells are located in the surficial aquifer, which is sensitive to contamination within the watershed (see Figure 2-6). Municipal wells within the LRRWMO tap the Mt. Simon aquifer, Tunnel City-Wonewoc aquifer, and as well as the surficial aquifer. In 1989 the state of Minnesota instituted the Minnesota Groundwater Protection Act, which identified the Minnesota Department of Health (MDH) as responsible for the protection of groundwater quality. Through its wellhead protection program, the MDH administers and enforces the Minnesota Water Well Code, which regulates activities such as well abandonment and installation of new wells. The MDH also administers the Wellhead Protection Program, which is aimed at preventing contaminants from entering the recharge zones of public well supplies. In 1997, the Wellhead Protection Program rules (Minnesota Rules 4720.5100 to 4720.5590) went into effect. Some public water suppliers are required to prepare wellhead protection plans (WHPPs), including the Cities of Andover, Anoka, and Ramsey. Through these wellhead protection plans, public water suppliers delineate drinking water supply management areas (DWSMA) for groundwater wells, assess the water supply's susceptibility to contamination from activities on the land surface, and establish management programs, such as identification and sealing of abandoned wells and education/public awareness programs. The DWSMA represents the boundaries of the recharge area to the well and is the area to be protected and managed by the wellhead protection plan. DWSMAs located within the LRRWMO are presented in Figure 2-7. The LRRWMO and its cities rely on infiltration practices to improve water quality and reduce stormwater volumes. Thus, the LRRWMO will continue to consider the possible impacts of infiltrated stormwater on groundwater quality. The MDH and MPCA also provide guidance for evaluating infiltration projects in areas with vulnerable groundwater supplies; the guidance considers the presence of wellhead protection areas, aquifer characteristics, land use, and other factors. This guidance is available from the MPCA website: s://st .r t r.. ,. . i £x.• / t r t*r n III r ►,t cti The LRRWMO is located within the source water protection area of the cities of Minneapolis and St. Paul. These cities draw drinking water from the Mississippi River approximately 16 miles downstream from the LRRWMO. Source water protection planning for these cities is being coordinated by the Minnesota Rural Water Association (MRWA). The cities of Andover, Anoka, and Ramsey are members of the MRWA. The 2-16