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HomeMy WebLinkAbout01-28-25 Agenda Packet Chair: Susan Johnson (2025) Secretary: Linda Hansohn (2026) Board Members: Gary Gerding (2025) Kent Stennes (2026) Melissa Jannakos (2027) Joel Gerich (2027) Andrew Elmquist (2027) Staff Liaison: David Swearingen Karth Lake Improvement District Board REGULAR MEETING Tuesday January 28, 2025 1245 W. Highway 96 Arden Hills, MN 55112 651.792.7800 www.cityofardenhills.org Agenda Board Meeting Convenes at 6:30 PM CALL TO ORDER/ROLL CALL 1. APPROVAL OF THE AGENDA 2. APPROVAL OF MINUTES of the previous meeting October 8,2024 3. PUBLIC INQUIRIES 4. OLD BUSINESS 4.1. Lakeshore owner outreach and education. Kent Stennes 4.1.1. Background: The KLIDB has reached out to KLID members in the past with flyers, events and door-knocking to increase awareness of what the KLIDB does, provide information to assist members in managing their shoreline and to recruit new board members. The Board agreed to consider another Ice Cream Social for Summer 2025. 4.1.2. Action: Consider sending out educational information and let folks know who to contact if they see something that shouldn’t happen and what things are good for them to do to and plan for outreach to new residents. 4.2. Karth Lake water level modeling and management process progress report. Renée Marino 4.2.1. Background: Hypothesis: a revision to the pump management policy can reduce water level bounce (i.e., range of high and low levels), which can improve lake quality and its environment while appropriately mitigating risk of damage to shoreline properties. Renee made a detailed presentation in October and a subcommittee was going to work with David to decide next steps. 4.2.2. Action: Discussion of subcommittee recommendations. 4.3. Bylaws review and possible modification. Susan Johnson 4.3.1. Background: Discussion of possible changes and clarifications to the KLIDB bylaws. 4.3.2. Action: Discuss the possibility of a change to the bylaws that has the City Council make appointments to the Board rather than an election. The elections have had little to no participation and seem like a waste of resources. The City Council already makes appointments to other commissions so it seems like this might be a reasonable change. 4.4. 4.4. Possibility of initiating a new study to identify status and refresh list of BMPs for future management of Karth Lake. David Swearingen 4.4.1. Background: The most recent Karth Lake study and BMP identification was performed by the Rice Creek Watershed District in 2009. The board would like to identify a plan for a follow-up assessment of Karth Lake’s current health and opportunities for improvement (BMPs). In April 2023, David Swearingen had described possible grant opportunities that the City of Arden Hills could pursue. 4.4.2. Action: The plan is still set for phase 2 of BMP #1 to be done in the 2026 PMP project. This project will also include replacing the retaining wall in Cummings Park. A consultant will be brought on board in February 2025 to help design the solution and look into grants that are available as well as look at other improvements that will help the lake water quality. Any updates? 5. NEW BUSINESS 5.1. Status of log removal by DNR gauge 5.1.1. Background: There are some logs by the DNR gauge in the lake that have moved the gauge and need to be removed. Karth Lake Improvement District Board October 8, 2024 Page 2 5.1.2. Action: Can David put removing those logs on the Spring agenda? The DNR cannot straighten the gauge until those logs are removed. 5.2. Water quality monitoring for Karth Lake for 2024. Gary Gerding 5.2.1. Background: The KLIDB has participated in the Citizen-Assisted Monitoring Program (CAMP) with the Metropolitan Council by coordinating volunteer sampling of Karth Lake’s water quality since 2006. 5.2.2. Action: Provide any updates for 2024 sampling program. 5.3. Water quality and impact of feeding migratory water fowl 5.3.1. Background: Some people have been feeding geese and crows and this has been impacted water quality in the lake. 5.3.2. Action: Discuss possible solutions 6. NEXT MEETING 7. ADJOURN Draft Minutes for Karth Lake Improvement District Board Regular Meeting 6:30 PM, Tuesday, October 8, 2024 CALL TO ORDER/ROLL CALL The meeting convened at: 6:30 PM. Present: Board Members: Susan Johnson, Chair, Linda Hansohn, Secretary; Kent Stennes; Gary Gerding; Andrew Elmquist; Joel Gerich; Staff Liaison: David Swearingen, Public Works Director Visitors and Karth Lake Improvement District members: Renee Marino, Jim Elliot Absent: Melissa Jannakos 1. APPROVAL OF AGENDA: The agenda was approved with the addition of New Business 5.3 to discuss possible impact of a proposed school rezoning near Cummings Park. 2. APPROVAL OF MINUTES: The minutes of the previous meeting on June 6, 2024 were approved with no changes 3. PUBLIC INQUIRIES: None. 4. OLD BUSINESS 4.1. Lakeshore owner outreach and education. Kent Stennes. 4.1.1. Background: The KLIDB has reached out to KLID members in the past with flyers, events and door-knocking to increase awareness of what the KLIDB does, provide information to assist members in managing their shoreline and to recruit new board members. Several lakeshore properties have or are soon expected to have new owners that have not benefited from past communications and an update on the lake’s current status to continuing owners would be helpful. 4.1.2. Discussion: Discussion of the Cummings Park Ice Cream Social and if this is something we would want to repeat in the future. Decided to consider it next Spring and if we do have it, perhaps make it earlier in the summer. 4.2. Karth Lake water level modeling and management process progress report. Renée Marino 4.2.1. Background: Hypothesis: a revision to the pump management policy can reduce water level bounce (i.e., range of high and low levels), which can improve lake quality and its environment while appropriately mitigating risk of damage to shoreline properties. 4.2.2. Discussion: Renée reviewed the hydrology model with Matt Kocian (RCWD) and Bret Zimmerman (Houston Engineering) and gave a detailed presentation discussing the conclusions and possible ways to use this information. The presentation document is included separately in the packet. Renee has spent 3 years working on this project. An interesting observation was made that if Karth Lake was not pumped in the past and going forward, the water level would go above Amble Drive. Since 1980, there has been 30 feet of water pumped out of Karth Lake. In other words, this is not strictly a problem of the people who live on the lake, it is the entire watershed. This really needs to be shared with the City Council. 4.2.3. Action: The report includes multiple pumping strategies and a small group has been assigned the task of reviewing the strategies with David Swearington to come up with a recommendation to present to City Council. The members of the Small Group are Joel Gerich and Kent Stennes. 4.3. Summary of Weed Removal project. Susan Johnson 4.3.1. Background: Lake weed removal was done this summer. This is an annual activity to help reduce the weed level in the lake. It is voluntary for homeowners to sign up for this service. 4.3.2. Discussion: Susan presented the results of the project. The lowest number of residents participated this year, There were only 18 households. The cost was almost $3000 more than the previous year ($9825 for 131 hours of labor). She was able to get the bill reduced but contributions were not enough and the extra funds came from the Arden Hills Foundation money that was available. If we do this project next year, there needs to be a minimum contribution for each household that participates. The final stats were 2.34 hours/bag at $175/bag. There was a total of 56 bags collected. 4.4. Bylaws review and possible modification. Susan Johnson 4.4.1. Background: A preliminary review of the bylaws causes there to be questions regarding who is a member of KLID, how elections should be run going forward, and who can vote 4.4.2. Discussion: Composition of the board is unclear as well as terms of office, Susan wrote a draft update to the bylaws and would need to send to the city attorney for review and then approved by the city council. The proposed bylaws indicate that there should be 1 ballot per parcel in the Karth Lake district and only 1 person per parcel to serve on the board. The city will mail out ballots to each property at least 2 weeks before the 2nd Tuesday in April which is the annual date for the election meeting. An observation that Susan made was that the City Council could just appoint members and not have an election. The Board approved a motion to go over the changes with the City Attorney. 4.5. Possibility of initiating a new study to identify status and refresh list of BMPs for future management of Karth Lake. Joel Gerich and David Swearingen (change title to reflect work that will be part of PMP for 2026) 4.5.1. Background: The most recent Karth Lake study and BMP identification was performed by the Rice Creek Watershed District in 2009. The board would like to identify a plan for a follow-up assessment of Karth Lake’s current health and opportunities for improvement (BMPs). In April 2023, David Swearingen had described possible grant opportunities that the City of Arden Hills could pursue. 4.5.2. Discussion: The plan is still set for phase 2 of BMP #1 to be done in the 2026 PMP project. This project will also include replacing the retaining wall in Cummings Park. A consultant will be brought on board in February 2025 to help design the solution and look into grants that are available as well as look at other improvements that will help the lake water quality. 5. NEW BUSINESS 5.1. Conversation with DNR regarding Purple Loosestrife. Susan Johnson 5.1.1. Background: Approximately 20 purple loosestrife plants have been identified in Karth lake. They are all in the water so we need DNR approval to remove the plants 5.1.2. Action: Susan talked to the DNR about this situation and got permission to remove any purple loosestrife in the lake 5.2. Water quality monitoring for Karth Lake for 2024. Gary Gerding 5.2.1. Background: The KLIDB has participated in the Citizen-Assisted Monitoring Program (CAMP) with the Metropolitan Council by coordinating volunteer sampling of Karth Lake’s water quality since 2006. 5.2.2. Action: All of the data will be available electronically just prior to the April Board meeting. This year there was very low seque depth. 5.3. Proposed school site near Cummings park 5.3.1. Background: Linda received an email detailing plans for a school to move into the old Fair Isaac location. There were lots of details about the plan but the actual formal application request has not been completed 5.3.2. Action: Wait until the formal application has been submitted and tell City Council that we would like to be involved in any discussions of changes that could potentially impact the lake. 6. NEXT MEETING: Tuesday, Jan 14 2025, at 6:30 PM at City Hall. 7. ADJOURN Karth Lake Pumping Strategy Assessment Tool Results as of 10/8/2024 Prepared by Renee Marino via expansion of a model prepared by Houston Engineering under Matt Kocian, Rice Creek Watershed District’s, funding and oversight Conclusions of review on 9/30/2024: “The spreadsheet model is an acceptable tool for looking at various pumping strategies and lake level response.” –Bret Zimmerman, PE (Licensed in MN, ND), Civil Engineer | Principal, Houston Engineering, Inc. Purpose •Use the Karth Lake Hydrology Model to consider the benefits and risks of the current and alternative pumping strategies •The current pumping strategy incorporated into the 2003 DNR Permit consists of: •Before October 1, begin pumping when Karth Lake’s elevation reaches 936 elevation (feet above sea level) and continue pumping until the elevation is 934 feet (“936=>934”) •Starting October 1, begin at 935 and pump to 934 (“935=>934”) Note: The URS hydrology study presented by the City of Arden Hills to the DNR in support of the 2003 permit is ambiguous as to whether these elevations use the 1929 standard (NGVD29) or the 1988 standard (NAVD88). NAVD88 = NGVD29 + 0.16. This model assumes that the permit is stated in NGVD29 elevations. Background –1848 and 1989 surveys had no Karth Lake. By 1867 and 1874, “Ryan’s Lake” appeared in various shapes. It is land-locked with no outflow. Its appearance may be due to roads blocking the former flow north into Marsden Lake and ultimately Rice Creek. The pond at Hwy 96 and Lexington has existed throughout, but is bisected today by Hwy96. 1848 1859 1867 1874 Karth Lake’s level history demonstrates a 5 foot bounce: from 933 to 938. A 3 foot bounce within a few year period is more typical. •Karth Lake’s level before development was below 930. •Housing developments in the late 1970s to early 1980s added impervious pavement and a street sewer system that transported water from greater distances through pipes directly into the lake. This increased the watershed area and moved more water directly into the lake that would have previously been partially absorbed by soils. •Subsequent development of commercial impervious areas and the Shoreview townhouse development in the late 1990s have added to the impervious surfaces that drain directly into the lake. Karth Lake’s surrounding elevations are shown in this 2022 Lidar map overlaying a satellite map. Finer detail is available online. Key points: •The lowest lying houses on the northeast side of the lake begin just above 942 •Amble Drive varies from 946 to 960 •Houses on the southwest side of the lake begin at 960 •If Karth Lake were at the elevation of 960, parts of Lexington Avenue and Highway 96 would be underwater Using RCWD’s watershed map superimposed on the 2022 Lidar map: The sum of the area in the blue squares on the 2022 Lidar map with the watershed map overlay results in a estimate of 142.9 acres, which matches the RCWD watershed estimate. Karth Lake’s watershed per Rice Creek Watershed is 142.9 acres, confirmed by this mapping estimate: Superimposing an earlier watershed (see inset) that must have been from just prior to the housing development shows the growth due to development. This implies a watershed of about 40.9 acres. The current watershed of 142.9 acres is 250% larger than this original. The sum of the blue and green squares (streets, parking lots, etc.) is 25 to 28 acres. The lower number assumes that the five green highlighted squares do not drain directly into the lake. The best fit hydrology model implies impervious of 25 acres so agrees to this smaller estimate. Estimating impervious acreage: Hydrology Model Results – 2024 The hydrology model developed by Houston Engineering and extended to full year daily projections by RMarino provides a very good fit to 2024 data. Inputs: •Daily local rain from MNClimate •Evaporation from the UofM St. Paul campus •Topography from MN State 2022 Lidar data and Kathy Johnson’s fish finder depths •Pumping rate from specs and fit to first 11 days of 2024 pumping results (235 gallons/ minute) •Actual lake levels from DNR gauge monitoring program Hydrology Model Results – 2022-2023 The hydrology model performs well through mid- August but over-predicts later lake levels for 2022- 2023. This may be due to drought conditions. Recent studies of Turtle Lake and others report that low ground water tables can create a “negative vortex” where water is depleted through springs. While springs do not appear to be a source of water for Karth Lake, they could reduce water levels during extreme drought. Rain’s Effect A single day’s rain increases lake levels by: 1.The inches of rain that fall directly on the lake (this chart for when the lake is 19.5 acres) 2.The rain that runs through the storm sewer system into the lake from 25 acres of impermeable surfaces 3.Run-off from other surfaces in the watershed. For a daily rain in isolation, the first 2.25 inches of rain will be absorbed, then start to run off into the lake. For multiple days of rain, the wetter soil causes a single day’s run-off to begin sooner. => It would take an impervious area of under 5 acres to achieve a stable lake level. Typical factors are: •annual evaporation of 32 inches •annual rain of 26 inches (assume daily rain < 2.25 inches, so no run-off) •the beginning and ending lake level would be the same if the impervious area is about 5 acres •Since Karth Lake has 25 impervious acres, pumping is necessary to prevent long term rises in lake levels. Historical daily rain data used in model •Average annual rainfall: •1961 to 1975 = 20” •1977 to 2023 = 24” •Min 1976 < 9” •Max 2002 = 35” •Max single day rains: 1965 (5.2”), 1987 (5.5”), 1997 (5.0”) and 2011 (5.5”) •1997 (striped bar) => most challenging year for all pumping scenarios because of the pattern of rain (dry then many days of rain). •Climate change impact: more intense storms, higher maximum daily rains, deeper droughts •Annual rains to 36” (20% over 2024 YTD) •Max daily rain up to 7.0” Snow’s Effect? •Hydrology Model covers May through October. •Snow (Winter) can impact November – April levels, which are not modeled. •Lake levels between 10/31 and 5/1 have historically risen or fallen. Turtle and Snail winter changes were considered for use as a proxy, but rejected because of their active pumping programs and different circumstances. •Instead, we are assuming no change in Karth Lake’s level from 10/31 to 5/1. •At the same time, the carryover from the prior year’s ending level does impact the assessment of pumping strategies. Key attributes to consider from a pumping strategy are: •Max: Likelihood (risks) of extreme high water levels to buildings, docks, trees, erosion and increased runoff of silt. •Min: Likelihood (risks) of extreme low water levels: increase algae, lake weeds, winter oxygen depletion and fish kills, sandy edge expanding invasive plant growth (purple loosestrife), bacteria blooms unsafe for swimming and general loss of recreational value. •Bounce: Difference between max-min levels within a year •General lake levels: Median, inner quartile range (between 3rd and 1st quartile levels) •Implementation: Expected years with pumping, days within a year and number of on/offs affect staff time and pump wear and tear Pumping strategies considered so far: •DNR: 936=>934 through September, then 935=>934 (October and November) •Alt0: 936=>934 •Alt1: 936=>935 •Alt2: 936=>935.5 •Alt3: 935=>934.5 •Alt4: 935.5=>934.5 though August, then 935=>934.5 •Alt5: 935.5=>934.5 Effects of Pumping •The six pumping strategies considered here materially affect the expected outcome. •While the difference between each pumping strategy will be the focus of the remaining analysis, it is important to appreciate how important pumping is to maintaining the current character of Karth Lake. Min/Max for all pumping strategies •All experience their maximum level in 1997 of 937.2 to 938.1. An abrupt pattern of several days of heavy July rain after a dry May and June causes all strategies to start pumping on the same day and continue pumping for nearly three months. •All pumping strategies experience their minimum levels in 1976 and 1977 of 931.4 to 932.6. •The DNR policy performs worse with the lowest minimums in 1976-1977, 2007-2009 and 2023. In 1987-1990, other policies perform worse than the DNR policy. Single year bounce (max-min levels) for multiple pumping strategies •The highest single year bounces occur with the DNR policy and the related Alt0:936=>934 all year (red and dark green in this chart) Summary Statistics •Goal: minimize bounce and risk of extreme high waters while keeping lake levels generally above sandy shoreline at 934 •All alternative strategies reduce the bounce compared to DNR and Alt0 •Alt2: •minimizes bounce and pumping needs and allows a higher average lake level •but has the highest max level in the single year 1997 of these 63 modeled years •Alt3 has a similar low bounce but has more sandier shores with the lowest average and max levels •Alt4 is more of a middle ground with lowest max level and slightly higher bounce For Years 1961-2023 For Years Beginning Levels Based Upon Prior Year Average of Annual Statistics Pumped, without Turtle/Snail Lake's Snow Effect Min Level Elev Q1 Elev Q2 (Median)Elev Q3 Q3-Q2 Max Level Avg 1 Yr Bounce Max 1 Yr Bounce Max 5 Yr Bounce Years Pumped Days Pumped Avg Days Pumped DNR (936=>934 thru Sept,then 935=>934)931.4 934.3 934.6 935.0 0.7 937.2 1.8 3.2 5.0 47 1,841 39 Alt0 (936=>934)931.4 934.3 934.7 935.2 0.9 938.1 2.0 4.1 5.0 39 1,829 47 Alt1 (936=>935)932.2 934.9 935.2 935.5 0.5 937.7 1.5 2.9 4.7 47 1,770 38 Alt2 (936=>935.5)932.6 935.2 935.4 935.6 0.5 938.1 1.3 2.7 4.5 52 1,767 34 Alt3 (935=>934.5)931.7 934.2 934.4 934.7 0.4 937.2 1.3 2.8 4.9 54 1,844 34 Alt4 (935.5=>934.5 thru Aug,then 935=>934.5)931.9 934.3 934.6 934.8 0.5 937.2 1.4 2.9 4.8 53 1,832 35 Alt5 (935.5=>934.5)931.8 934.4 934.7 935.0 0.6 937.3 1.5 2.9 4.8 47 1,811 39 Minimum Maximum Comparing Alt2 to Alt4 Strategies: Levels •As shown, Alt2’s min and max lake levels are higher than Alt4’s in all years. •Their median levels, from the prior table are 935.4 (Alt2) versus 934.6 (Alt4) Comparing Alt2 to Alt4 Strategies: Bounce Comparing the bounce of these strategies as a function of total rain, Alt2 (the green dots) are nearly always lower than Alt4. Comparing Alt2 to Alt4 Strategies: Pumping For the most part, pumping occurs in the same years for Alt2 and Alt4 Next Steps •RCWD has a defined but more limited part of the process going forward •Karth Lake Improvement District board/members to evaluate and recommend any pumping strategy changes to the City of Arden Hills •The City of Arden Hills to address implementation issues •The City of Arden Hills has the responsibility to choose which, if any, revisions to the DNR strategy to adopt •If the strategy changes, the City of Arden Hills will need to with a request that the DNR modify the 2003 permit. Houston’s involvement and review can be a part of the evidence presented to the DNR.