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controls. The existing floating pump would be a back-up should the primary pump fail during periods of heavy rains (as it has in the past). • The project also recommends a revision to the current pumping strategy that is expected to reduce erosion and improve water quality. The revised strategy is expected to extend the expected life of pumping equipment. • The Karth Lake Improvement District Board supports the feasibility and design objectives initiated by the City and described in the Bolten & Menk, Inc. 2026 PMP study regarding storm sewer pumping improvements and retaining wall replacement design.3 KLIDB also urges a solution that is consistent with a Longterm vision for the health and functionality of the Karth Lake watershed. Background: The project described above was initiated to explore modification to the current lake level pumping plan with the goal of reducing Karth Lake's extreme high and low lake levels ("bounce") of 3-5 feet. A reduction in bounce is expected to reduce erosion, improve water quality and improve the health of fish, vegetation and wildlife in and around the lake, as well as discourage expansion of invasive plant species. The findings of this work have implications beyond pumping strategy modifications to the issue of overall surface water management within the Karth Lake watershed. History: Beginning in the 1970s, land use surrounding Karth Lake began transitioning from agricultural to residential and business use. Surface water management, including installation of street sewers with outlets into Karth Lake, caused a near quadrupling of the watershed: from 41 to 143 acres. These include about 25 acres of impervious surfaces, more than the Jake's normal surface area of 20 acres.' Karth Lake has no natural outlet and is assigned to the RCWD even though it does not naturally drain into Rice Creek. Since development around the lake began, periods of flooding have occurred and been managed by the City using contractors to temporarily pump water into street sewer systems to the north or west that drain into Rice Creek. Known incidences of temporary pumping occurred in 1984, 1986 and 2002. In 2003, the City retained a hydrology firm, URS, to propose a permanent pumping and maintenance plan for Karth Lake. The City submitted URS' report to the DNR in support of DNR permit #2003-3078. That permit allowed construction of a permanent pumping facility and adopted URS' proposed parameters for operating the pump (the DNR Pumping 3 Pp. 11-12 of Exhibit A to 2026 PMP Street and Utility Improvements, City of Arden Hills. 'These impervious surfaces cause a nearly immediate lake level rise of 2.25 inches for every 1.0 inch of rain. During periods of frequent and quick rains, run-off from the rest of the watershed can cause the lake level to rise by as much as a 4:1 multiple of rainfall. Page 2 of 4