HomeMy WebLinkAbout04-12-22 Agenda Packet Chair:
Tony Peleska (2023)
Secretary:
Gary Gerding (2022)
Board Members:
Aisha Elmquist (2024)
Linda Hansohn (2023)
Kathy Johnson (2024)
Susan Johnson (2022)
Renee Marino (2024)
Staff Liaison:
David Swearingen
Karth Lake Improvement
District Board
REGULAR MEETING
Tuesday
April 12, 2022
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
3. BOARD MEMBER ELECTIONS: Terms expire for Susan Johnson and Gary Gerding
4. ELECTION OF CHAIR AND SECRETARY
5. PUBLIC INQUIRIES
6. OLD BUSINESS
6.1 Remediation of BMP #1 Site, Plan Next Steps – David Swearingen and Board
6.1.1 Background: In 2021 the city completed installation of a drain that brings the runoff from the parking lots
and roads south of Karth Lake down to the lake. This eliminates the erosion that took place as the runoff flowed
down the hill and into the lake. The next step is to divert the drain to empty in a ponding area to filter out the
nutrients, oils, organic compounds, and soils in the runoff.
6.2 Progress Report on No-Trespassing Sign – David Swearingen
6.2.1 Background: The Board requested replacement of the No-Trespassing Sign to warn the public not to cross
the land bridge from Cummings Park to the residential area to the north. Renee M. noted that the sign was
agreed to and authorized in the July 14, 2009, KLIDB Meeting. Action from 10/26/22 Meeting: David
Swearingen will review this history and decide what to do.
6.3 Add Grit Chambers to storm drains that empty into Karth Lake and do not have Grit Chambers now. Next
Steps: Show map of existing storm drains and grit chambers that empty into Karth Lake – David Swearingen
6.3.1 Background: There is only one storm drain inlet to Karth Lake that does not have a grit chamber: the one
on Karth Lake Circle. This will be corrected when that road is repaved in about 2026.
6.4 Karth Lake water level modeling and management process progress report – Renee Marino
6.4.1 Background: Renee Marino’s 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. For more background on this topic, please
review the following link in advance of the meeting:
https://www.dnr.state.mn.us/climate/waterlevels/lakes/volunteering.html
Karth Lake District Board
April 12, 2022 Page 2
7. NEW BUSINESS
7.1 Plan for 2022 removal of excess lake weeds and debris and control of invasive purple loosestrife.
7.2 Report of Results of 2021 water quality monitoring for Karth Lake – Gary Gerding
8. NEXT MEETING
9. ADJOURN
Minutes of Karth Lake Improvement District Board
Regular Meeting 6:30 PM, Tuesday, July 13, 2021
Approved: October 26, 2021
1.Call to Order/Roll Call
1.1The meeting convened at: 6:49 PM.
1.2 Present:
Board Members: Gary Gerding, Secretary; Aisha Elmquist; Linda Hansohn;
Susan Johnson; Renee Marino (chaired meeting)
Staff Liaisons: David Swearingen, Interim Public Works Director; Kyle Axtell,
Water Resource Specialist / Project Manager, Rice Creek Watershed District;
David Grant, Mayor.
1.3 Absent: Kathy Johnson, Tony Peleska, Chair
2. Approval of Agenda
The agenda was approved as modified.
3. Approval of the minutes of the previous meeting: The minutes of the previous
meeting on April 13, 2021, were approved as written.
4. Public Inquiries: None
5. Old Business
5.1 Remediation of BMP #1 Site
5.1.1 Progress Report – David Swearingen
Construction will start in August. Estimate one month to complete. Found that sediment
was plugging the existing storm drain at the end of the road above the site.
Renee M.: Can we plant under the power lines?
David S.: The contractor will seed above the drain according to MNDOT standards. The
contractor will not be paid until the site is established and erosion stops.
5.1.2. Karth Lake BMP 1 Observations and Questions – Renee Marino
Karth Lake BMP 1 Observations and Questions – July 2021
• This photo shows
that the lake gauges
are completely out
of the water and a
bolt has come off of
the new stick. We
should ask David to
have this repaired.
[see Discussion
below.]
• Erosion and silt
flowing down from
the parking lots at
the BMP1 site.
• Several feet of dirt
have eroded after the
concrete ends from
the parking lots
• Silt has flowed over
the walking path. It
comes down the hill
and around the “dry
creek bed” by the
bench.
• A view up the “dry
creek bed.” This is
the outlet for storm
sewers and does not
carry water from the
parking lots.
Importantly,
although it is very
hard to see in this
photo, this sewer
outlet only has a few
inches open above
the silt. This is
therefore a different
issue from the
drainage off of the
parking lots. With
this much silt
coming from the
sewer outlet, we
should ask about grit
chambers at drains
that feed into this
sewer line. [See
discussion below.]
• This shows the
water crossing to the
north side of the
road above BMP 1,
just as is shown in
the storm sewer map
David had
previously provided
to us (labeled A in
the photo below)
• These photos
correspond to
David’s storm sewer
map as follows: The
flow of the water
and silt from the
road, around the hill
and over the walking
path by the bench is
shown at D. The
“dry creek bed”
storm sewer outlet is
at C. The water
crossing the road is
at A.
• I wonder the area
marked as B has
been considered as
an alternative
remediation. There
is a low area south
of the walking path
where B is pointing
that sometimes holds
standing water and
drains into Karth
Lake when its level
is high enough. This
probably acts like a
catch basin to allow
grit to settle before
going into the lake.
It looks to me like it
could handle holding
more water, similar
A B C D
to the pond that is
shown between the
lines marking A and
B. This area was
mentioned in the
Karth Lake plan
from 2009 as an area
that could filter
water before
draining into Karth
Lake. Would it be
possible to run a
short storm sewer
line from the
parking lot under the
road to empty into
B? It looks like there
is a sharp drop-off
there, so water at the
outlet would drop
into that the
depression like a
waterfall without
eroding the hillside
on the way down.
This solution would
probably handle the
majority of the water
that currently runs in
the path marked D
and would probably
be far less expensive
and also remove the
needed maintenance
of emptying the grit
chamber in the
current BMP
remediation design.
The Karth Lake
Board had asked if
we could use the
area in B (in
accordance with the
2009 Karth Lake
Study’s
recommendations)
to address BMP 1,
but were told it
would have to be a
future project, since
the current BMP 1
remediation design
is complete.
Wouldn’t this
alternative approach
offer a win-win
solution for all
concerned?
5.1.2.1. Discussion:
Mayor Grant: In the winter, consider drilling a good anchor for the lake gauge and
install a gauge that is more robust.
David S.: Re grit chambers: there will be grit chambers at the entrance to the new drain.
Re alternative remediation that Renee has proposed: Construction plans have been
reviewed, approved and contracted and construction will proceed as planned
5.2. Maintenance and improvement of Art Larsen Memorial Garden –
5.2.1. Background: The city planned to upgrade the sprinkler controllers in mid-May
and then set them to water the garden.
5.2.2. Sprinkler Status and Plans - David Swearingen: The new irrigation controllers
are installed and the sprinklers are watering the garden.
5.3. Add Grit Chambers to storm drains that empty into Karth Lake and do not
have Grit Chambers now. Next Steps: Plan to identify them; Identify likely dates
for adding Grit Chambers.
5.3.1. Background, David reported at the April meeting that: A Crew will inspect and
clean the grit chambers in the spring. The City hired WSB to create GIS record of storm
drains and grit chambers. Will include this on the list by mid to late summer. Pavement
upgrade scheduled for 2024 for Amble and neighborhood. Automated rating of streets
will be done soon. David will give updates at future meetings.
5.3.2. Grit Chamber Status Update - David Swearingen: The GIS record has not yet
been completed. They did find that the Karth Lake Circle storm drain did not have a grit
chamber so a grit chamber will be installed the next time that road is repaved.
6. New Business
6.1. Proposed changes in lake level control process - Renee Marino
Renee proposes that we do not pump the lake all the way down to the level set by the
DNR. This will allow for evaporation and help to prevent the extremely low lake levels
that we have experienced when there is a draught. Renee asked that David S. determine
the current pumping policy regarding pump start and stop levels. David said he would
also determine the pump capacity.
6.2. Plan for removal of excess weeds and debris for 2021– Susan Johnson
Susan said she would again invite donations for the removal of excess weeds and debris
from the lake. Susan said she would contract with Holtz Landscaping again this year to
do the weed removal. She will also have the Dive Guys remove the weeds from around
her dock and shoreline to see whether their method is more effective.
6.3 Report of highlights of phone conversation Paul Dykstra, President of the Lake
Johanna Improvement Society on 6/27/21. Gary was contacted by Paul Dykstra.
Paul currently obtains funding for lake improvements through voluntary Lake Johanna
Association dues. He is frustrated by the lack of participation and is considering the
possibility of setting up an improvement district so they could tax everyone around the
lake.
Paul asked: Is the KLIDistrict used to assess residents for annual lake maintenance?
Gary: No, we invite donations through the Arden Hills Foundation except for pump
related improvements.
Paul: A major expense is for chemically treating invasive curly leaf weeds for which they
have a permit. They also round up 20 geese/yr. with a permit granted due to swimmers
itch. They do not remove silt from the lake bottom.
7. Next Meeting: Tuesday, October 12, 2021 (later revised to October 26, 2021).
8. Adjourn
Respectfully Submitted,
Gary Gerding
Draft Minutes of Karth Lake Improvement District Board
Regular Meeting 6:30 PM, Tuesday, October 26, 2021
Call to Order/Roll Call
The meeting convened at: 6:30 PM.
Present:
Board Members: Tony Peleska, Chair; Gary Gerding, Secretary; Aisha Elmquist
via Zoom); Linda Hansohn (via Zoom); Susan Johnson (via Zoom); Renee
Marino
Staff Liaisons: David Swearingen, Interim Public Works Director; David Grant,
Mayor.
Resident: Jim Elliott
Absent: Kathy Johnson; Kyle Axtell, Water Resource Specialist / Project Manager, Rice
Creek Watershed District.
1. Approval of Agenda: The agenda was approved as written.
2. Approval of the minutes of the previous meeting: The minutes of the previous
meeting on July 13, 2021, were approved as written
3. Public Inquiries: None
4. Old Business
4.1 Remediation of BMP #1 Site
4.1.1. Progress Report - David Swearingen
David said the drain installation project has been completed and that grass has already
begun to grow on the displaced soil that covers the drainpipe.
Discussion:
Debris: Susan Johnson said there were some old tires near the upper grit chamber.
Jim Elliott noted that there was also a tire in the pond area and ladder in the lake.
Action: David S. said the city will clear this debris.
No-Trespassing sign needed: Susan J. said we still need a No-Trespassing Sign
to warn the public not to cross the land bridge from Cummings Park to the
residential area to the north. Renee M. noted that the sign was agreed to and
authorized in the July 14, 2009, KLIDB Meeting.
Action: David S. and Mayor Grant will review this history and decide what to do.
4.2. Add Grit Chambers to storm drains that empty into Karth Lake and do not
have Grit Chambers now. Next Steps: Plan to identify them; Identify likely dates
for adding Grit Chambers.
4.2.2. Grit Chamber Status Update - David Swearingen: There is only one storm
drain inlet to Karth Lake that does not have a grit chamber: the one on Karth Lake Circle.
This will be corrected when that road is repaved in about 2026.
Action: David S. will provide the board with a map of the locations of existing grit
chambers for storm drains that feed Karth Lake.
4.3. Proposed changes in lake level control process. Background: At the last meeting
Renee Marino proposed we stop the pump before we reach the target level to allow for
evaporation and avoid the very low levels that a drought could cause.
4.3.1. Define current process: when is the pump turned on and off? What is the pump
capacity? David Swearingen: DNR set the target high level at 936 feet and the target
low level at 934 feet. David will give Renee pump specifications the determine its
capacity in various conditions including lake level.
4.3.2. Karth Lake water level modeling process: Renee Marino’s 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.
Action: Gary G. will ask Matt Kocian and others at the RCWD to work with Renee M.
on the modeling project.
4.4. Was the pump used at all in 2021? No, according to David S.
4.5. Results of removal of excess weeds and debris for 2021– Susan Johnson
23 residents contributed and had weeds and debris removed from the lake
adjacent to their property.
164 bags of weeds removed from lake.
Susan also removed garbage and logs from the lake.
Thanks Susan!
5. New Business
5.1. The City Council recently rezoned Little Johanna from a Recreational
Development Lake to a General Development Lake (see ORDINANCE NO. 2021-
007). (Karth Lake is classified as a General Development Lake.) What is the
significance, advantages, disadvantages, etc. of each of these classifications?
David Swearingen: The main difference is that a General Development Lake has a
greater housing density.
5.2. Discovery of a few specimens of purple loosestrife, an invasive plant, on the
Karth Lake shores and preliminary plan to remove them. – Susan Johnson
Susan found a single plant on their property. Tony reported that it is growing on his
neighbor’s property. Gary emphasized that we need to aggressively eradicate this
invasive plant before it takes over the lake. Here is some information that Gary gleaned
from the MN Dept. of Agriculture and DNR. See:
https://www.mda.state.mn.us/plants/pestmanagement/weedcontrol/noxiouslist/purpleloos
estrife
https://www.dnr.state.mn.us/invasives/aquaticplants/purpleloosestrife/control.html
Purple loosestrife is found throughout Minnesota. The Minnesota Department of
Natural Resources estimates that infestations have been recorded in 77 of Minnesota's 87
counties, covering 58,000 acres of lake, river, and wetland habitats.
Purple loosestrife negatively affects both wildlife and agriculture. It displaces and
replaces native flora and fauna, eliminating food, nesting, and shelter for wildlife.
Purple loosestrife forms a single species stand that no bird, mammal, or fish depends
upon, and germinates faster than many native wetland species.
Purple loosestrife can be cut or pulled without a permit in Minnesota. It is important to
dispose of the plants away from the water. Allow the plants to dry out, then burn if
possible. Pulling purple loosestrife by hand is easiest when plants are young (up to two
years) or in sand.
Flower:
Plant
Infestation:
6. Next Meeting: Tuesday, April 12, 2022 at 6:30 PM at City Hall.
7. Adjourn
Respectfully Submitted,
Gary Gerding
Karth Lake Water Level Modeling ProjectProject and Status as of 3/25/2022
Karth Lake Water Level Modeling Project Purpose: The Karth Lake Water Improvement District Board has launched an effort to explore development of a lake level model to address modification of the current lake level pumping and maintenance plan. The goals of this effort would be to reduce the extreme high and low lake levels (the “bounce”). It is believed that a smaller bounce could improve water quality and the health of the fish, vegetation and wildlife in and around the lake. A modified pumping plan would also need to incorporate the current pumping plan’s purpose of mitigating the risk of property damage from high water levels. It should also address implementation, calibration and monitoring of the revised pumping plan.
Participants: Karth Lake Water Improvement District (KWID)Renee Marino, Gary Gerding, board membersCity of Arden Hills (the City)David Swearingen, Public Works Director / City EngineerRice Creek Watershed District (RCWD) Matthew Kocian, Lake and Stream SpecialistHouston Engineering, Inc.Chris Otterness, District Engineer for RCWD, hydrologistMinnesota Department of Natural Resources (DNR)Dan Scollan, East Metro Area Hydrologist
Summary of Current Status The historical Karth lake level measurements suggest that the City has successfully implemented the pumping instructions in the DNR’s 2003 Pumping & Maintenance Plan (attached) except when pump failure has occurred. Although that plan produces a pumping “bounce” of 2 feet, other factors such as evaporation have extended the bounce to as much as 4 feet. The erosion of the shoreline of Karth Lake due to this large bounce appears to have negatively impacted the quality of the water, fish populations, vegetation, residents’ efforts to stabilize shorelines, etc. The current project is seeking a pumping policy modification that would improve environmental outcomes while appropriately mitigating the risk of property damage.KWID, the City, RCWD, DNR, are in agreement to consider investigation of modifications to the pumping plan to improve the health of the lake and its surroundings.
A Framework to Achieve this Purpose is described in the following sections:A. Goals B. Data CollectionC. MeasurementD. Modeling and Stress TestingE. ValidationF. Management Policy G. Policy Implementation
A. Goals Today: 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. Historically:Pumping focused on mitigating risk of damage to shoreline properties. It did not address any potentially negative impacts of low lake levels.
Exposed Shore Below Tree Line Close to Pump, Fall 2021 and Winter 2022
This photo demonstrates the range of bounce: In October 2019, the water was close to the top of the Marino deck. As of January 30, 2022, a newly installed gauge on the closest pole shows the ice level is currently between 3.2 and 4.1 feet from the bottom and top of the side dock boards, respectively.Other measures:•In 2021, the lake level dropped to expose the street sewer outlets that drain into the lake, which has happened at least one other time in the past 20 years.•Several feet of shoreline from the lots shown here were eroded away between 2000 and 2013. •An attempt at lake shore restoration and stabilization with dogwood, sedge and other native plants in 2013 was unsuccessful when subsequent high waters killed all plants and resulted in further loss of shoreline. •In 2017, boulders were installed and fastened with spikes on the two lots shown here in another attempt to stabilize the shoreline. The work on the neighboring lot was partially funded by RCWD. It cost about $20,000 per lot and has so far remained in place through the bounce that has occurred since then.
B. Data Collection Today: Collecting history of historical measurements and reconcile measurement types. Historically:For the most part, levels have been collected every 1‐2 weeks while the pump has been on and reported by the City to the KWID Board. There is no level data for years of low water levels when the pump was not needed. Therefore, the full bounce of Karth lake has not been recorded.There is one DNR Lidar measurement in 2011. Unofficial measurements (calibrated to the original measuring stick) were made by a resident (Marino).
‐ 1 2 3 4 5 6 7 8 9 10 11 12 136/30/19746/30/19766/30/19786/30/19806/30/19826/30/19846/30/19866/30/19886/30/19906/30/19926/30/19946/30/19966/30/19986/30/20006/30/20026/30/20046/30/20066/30/20086/30/20106/30/20126/30/20146/30/20166/30/20186/30/2020Feet on Original Gauge by PumpHistory of Karth Lake Depth Measurements(Measurements made by: City=Blue; DNR Lidar=Orange; Marino=Red)1974 Normal Depth before development was 930 feet above sea levelDNR "Pump On" Depth 936 feet above sea level (if equals 10' on Original stick)DNR "Pump Off" Depth 934 feet above sea level2002 temporary pumping1984 temporary pumping1986 temporary pumping2004+ permanent pump2019 pump failed
‐ 1 2 3 4 5 6 7 8 9 10 11 12 136/30/19746/29/197810/9/19837/12/198410/15/19949/15/200210/28/20027/8/20047/26/20048/6/200410/18/200510/26/200511/7/20057/2/20077/16/20079/2/20078/30/20119/27/201110/13/20116/24/20137/8/20137/25/20138/8/20136/2/20146/13/20146/27/20147/7/20147/23/20148/13/20147/15/20158/21/20159/15/20159/29/20154/11/20168/3/201610/30/20168/15/20178/28/20179/11/20179/18/20176/19/20196/28/20197/23/20199/10/201910/19/20195/1/20205/11/20205/18/20206/1/20206/15/20207/6/20207/20/20208/10/20202/11/20211/30/2022FeetHistory of Karth Lake Depth Measurements, All Days with Observations(Measurements made by: City=Blue; DNR Lidar=Orange; Marino=Red)1974 Normal Depth before development was 930 feet above sea levelDNR "Pump On" Depth 936 feet above sea level (if equals 10' on Original stick)DNR "Pump Off" Depth 934 feet above sea level
C. MeasurementToday: Future measurement should begin with calibration and a possibly installation of a new gauge. RCWD and DNR have offered to install and calibrate either a permanent gauge in deeper water with a cement base or a more temporary gauge annually. Future measurement frequency and responsibility should be determined. One possibility is participation in a DNR volunteer lake level monitoring and reporting program at www.dnr.state.mn.us/climate/waterlevels/lakes/volunteering.htmlHistorically:A measurement stick was installed in 2004 by the pump that extends two feet above lake bottom measuring 8 ‐10 feet. Actual lake levels outside this range have been reported as, for example, “above the stick about 4 inches.” There is no conversion to the DNR permitted elevations, but it appears that this range may correspond to the DNR pumping instruction range of 934‐936 feet above sea level. A new stick was installed in 2020, but is damaged and unusable.
The photo at the left shows the original gauge in the fall of 2021. It measures 8’ at the base and 10’ at top.A new gauge installed in 2020 by the City is broken and unusable.A resident, Renee Marino, has recently installed a gauge on her dock and calibrated it to the original gauge. As of January 30, 2020, the ice level is below the bottom of the original gauge, but would read 7.2’ if the original gauge had been installed in deeper water.
D. Modeling and Stress TestingToday: RCWD has agreed to assist by “providing hydrologic/hydraulic data and modeling products.” Matthew Kocian of RCWD will work with Chris Otterness from Houston Engineering, Inc. to leverage recent similar analyses in the RCWD. Chris, a hydrologist, is on retainer with the RCWD and this is project is within the scope of the RCWD mission (“mitigating risk from flooding, and potential water quality impacts from water level bounce (i.e. shoreline erosion).” Therefore, RCWD will fund the modeling effort. Two members of the KLID board, Renee Marino and Gary Gerding, will participate in this effort.Historically:The City retained a consulting firm, URS, to study and propose a pumping and maintenance plan for Karth Lake in 2003. They issued their report to a hydrologist with the DNR in support of permit 2003‐3078 allowing construction of a permanent pumping facility for Karth Lake.
Pump Rate EstimationsPump #1: per DNR documentation, pump installed in 2004 was to pump at the rate of 360 gallons/minute. Lift (as shown in the two drawings) was about 63 feet.Pump #2: Pump installed in 2020 was FLYGT Model BS2840 228‐4, 4" discharge. (see B 228 MT in chart below fromwww.xylem.com/siteassets/brand/flygt/flygt‐resources/flygt‐resources/xylem‐flygt‐2840‐datasheet‐60hz.pdf)Per the chart, if the vertical height is about 63 feet, the pumping rate should be around 320 gallons per minute. Lake level (DNR mid‐range) 935 feet above Sea LevelFernwood Ave (Cummings Park Dr.) 998Total Lift 63Implied rate from chart 320 gallons/minute
Growth in Watershed versus Lake LevelsPrior to housing and industrial development north and south of lake that occurred in the late 1970s/early 1980s, the watershed area was as shown below (from 2009 DNR Karth Lake study). In 1974, 1977 and 1978, lake levels per DNR & URS were about 930 feet above sea levelBy 1983, levels had risen to 934+ feet. The lake size increased and there was a substantial lossof trees, sitting in 3 or more feet of water. Temporary pumping occurred in 1984 and 1986 when the levels reach over 936 feet. Pumping brought levels down to 934 feet. Around 2000, Shoreview townhomes were completed, which appears to have expanded the watershed eastward.As of 2009, Karth Lake’s water surface area was 20.5 acres and the watershed area was 117.74 Acres, of which an estimated 35% was impervious surfaces. In 2002, levels reached over 938 feet. Temporary pumping occurred in 2002 and the first permanent pump was installed in 2004.After the first pump failed in 2019, levels rose to almost 937 feet.After the new pump was operated in 2020 and was followed by a drought during 2020‐2021, levels dropped to around 933 feet.
Comparison to Snail Lake Reflects Watershed GrowthKarth Lake elevations were about 47 feet higher that those of snail lake in 1970s. Adjusting Karth Lake observations downwards by 47 feet offers another view of the effects of development on lake levels.Monthly lake level data for Snail Lake supports the hypothesis that the rise in Karth Lake levels have been primarily due to expansion of its watershed that occurred in the late 70s and early 2000s, rather than due to changes in weather.There were no Karth Lake measurements during low water level years of 2009 and 2010, but residents observed significant declines, as did Snail Lake. Snail Lake requested a diversion of water from Vadnais around that time. Its levels have been on the rise since then through the beginning of the current drought.Snail lake data from https://files.dnr.state.mn.us/cgi‐bin/lk_levels_dump.cgi?format=csv&id=62007300
E. ValidationToday: Lake level model development should incorporate historical lake level data, other data collected from a 2009 DNR Karth Lake study, recent RCWD hydrology analyses and weather data. Going forward, validation should be done by frequent measurements during the first year or two to confirm validity and usefulness of the model. Further, the model should be “stress‐tested” with historical weather data to quantify the range of expected bounce and risk of property damage from high water under different pumping policies.Historically:Not applicable.
F. Management PolicyToday: A revised pump management policy should emerge from this project.Historically:The 2003 Pumping & Maintenance Plan developed by URS with the DNR specifies that between April and September, the pump should be turned on at 936 above sea level (which may be the top of the stick) and turned off at 934 (the bottom of the stick).
G. Policy ImplementationToday: Implementation of a revised plan must be feasible. One option is to continue the current method of City personnel visiting the gauge by the pumping station and responding to inquiries from residents. Another option might be an automated system such as what RCWD has helped install in Fridley Dam on Rice Creek. After a revised plan is developed and approved, pump operation should be recorded and reviewed and revised further, if needed.Historically:The historical lake level measurements suggest that the City has generally successfully implemented the pumping instructions in the DNR’s 2003 Pumping & Maintenance Plan except when pump failure has occurred. This is despite the turnover of personnel involved with pumping and a loss of the Maintenance Plan and DNR permit records.
Appendix: Lake Level Data, p. 1
Appendix: Lake Level Data, p. 2
Appendix: Lake Level Data, p. 3