So, on Monday (today) there will be a meeting of the Yahara Chain of Lakes – Lake Levels Task Force and they have two reports they will be looking at – one is a report from the technical work group (Feb. 1, 2019). The other is recommendations of the Stormwater Technical Advisory Committee of the Dane County Lakes and Watershed Commission and the Capital Area Regional Planning (May 4, 2017). So, what are the solutions? Here’s a summary of my very un-expert view of the over 100 pages of reports.
Important disclosure: this is not my area of expertise whatsoever! However, I felt the need to get better informed since I haven’t really dealt with this in the past 10 years since I was an alder. This is what I could glean from the reports, in very layperson terms. For those of you in the same shoes as me, I figured you might appreciate what I found. You can read the reports yourself to get more details and all the technical speak. The report has lots of numbers and graphs and maps and charts and photos, so you should take a look. However, I’ve read lots of reports in my day, and here’s what I found to be of interest. (My enviro friends can just start laughing now . . . but I will remember next time we start discussing affordable housing, homelessness and/or tenant-landlord law and you’re completely lost!)
MAY 2017 REPORT RECOMMENDATIONS
These recommendations are a result of identifying several causes of the flooding. Development, lake levels, water leaving the lakes and increased precipitation are all factors. More specifically:
– Slow rate of drainage to the Rock River (water doesn’t leave the area fast enough)
– Annual maximum water levels of Lake Mendota have been generally increasing since 1916, and has accelerated since 1970s.
– Increase in impervious surfaces from urban development in the watershed (water runs off the land instead of being absorbed into it)
– Increases in precipitation
– Increased development in the urban and suburban watershed and loss of drainage areas (water can’t pond or pool in areas where it used to)
In addition to the lakes, the streams are impacted and there is more erosion in the stream beds. More sediment and phosphorus are transported which is bad for water quality. The ground water doesn’t recharge as fast because the water runs off instead of into the ground. This has reduced the amount of springs around the lakes.
The recommendations in the report are as follows:
1. Require county-wide that new development not increase stormwater runoff volumes above pre-development levels (100% volume control).
2. Require 50% volume control for redevelopment in existing urban areas.
3. Require 100% volume control of runoff for internally drained areas (i.e. greater than 20,000 ft2 of one foot or deeper ponded area); require storage volume within internally drained areas for back-to-back 100-yr, 24-hr storms; require development of emergency drawdown (pumping) plans for internally drained areas.
4. Establish a county-wide volume-trading (fee-in-lieu) program as an alternative when on- site control would be costly, inefficient, or prohibited.
5. Consider capital projects and/or grant funding for implementing volume control practices in developed areas, and in rural areas not subject to volume control regulations.
6. Develop policies and procedures to facilitate the standardization of the design and installation of infiltration practices.
How do they do these things? Here’s some of the suggestions:
– Bio-Retention facilities (including rain gardens)
– Infiltration basins
– Subsurface infiltration systems
– Tree trenches
– Vegetated swales
– Pervious pavement
– Green roofs
Dane County revised its ordinances in 2004 to exceed DNR requirements for development and stormwater runoff and the Town of Westport, Village of DeForest and Village of Cross Plains have ordinances that (mostly) require new development to have zero impact on the water runoff – i.e. the water run off has to be the same when they are done with the development as it was before the development. However, there are some gaps in Dane County’s Ordinance:
a. The maximum required volume control is 90%. This means that “stay-on” (the amount of rainfall that infiltrates or evapotranspirates rather than running off) must be at least 90% of the pre-development stay-on for the average annual rainfall.
b. The land area dedicated to meeting the stay-on requirement is “capped” at 2% of the development site. When the cap area is reached, the development instead meets a reduced annual recharge requirement (which may be more difficult to meet than the infiltration standard).
c. In accordance with State standards, infiltration exemptions are granted to redevelopment sites and to sites for which the soil infiltration rate beneath an infiltration practice would be less than 0.6 inches per hour (where the soil layer is not easily removed or manipulated), and for other cases such as high groundwater and shallow bedrock. Exempted sites are not required to achieve any volume control, even though some practices (e.g. green roofs) may be feasible and effective.
Development also messes with where the water flows
Under the present ordinance, development in internally drained areas can result in increased volume of stormwater runoff, and increased water levels in local ponds and wetlands. Increases in runoff attributable to development in a closed watershed can increase local flood risk and lead to draining the area to a previously unconnected downstream water body. Such drainage is not currently regulated by the Dane County ordinance.
Here’s the more detailed version of how they recommend to change the county ordinance:
1. The County should revise the Dane County Stormwater Ordinance to most efficiently prevent future increases in stormwater runoff volume due to land development in each major watershed in the County, contingent on the development and adoption of a runoff-volume trading / fee-in-lieu program, as described in section 5. The revised ordinance should:
a. Require 100% volume control (either on or off site) of the pre-development runoff volume based on average annual rainfall for new development that is not in an internally drained area and not a redevelopment site. 90% volume control shall be met onsite where technically feasible. This requirement also eliminates caps and exemptions, and should not go into effect until a volume- trading / fee-in-lieu program has been established by the County with an explicit goal of creating projects with the lowest cost/volume ratio and where possible partnering on projects to reduce overall costs and increase benefits. For a site exempted by WDNR standards, the fee in lieu credit would be allowed to exceed the 10% gap between 90% and 100%.
b. Require 50% volume control (either on or off site) of the pre-development runoff volume based on average annual rainfall for redevelopment in existing urban areas. Redevelopment areas would be allowed to meet this requirement using fee-in-lieu program credits.
c. Development sites with approved stormwater management plans that predate these changes to the stormwater ordinance should be exempted (grandfathered).
d. Although flooding of the Yahara Lakes are a focus of this effort, the volume control requirement should be applied county-wide. Flood damage is experienced county-wide and will only increase unless a ‘no net change’ standard is enacted.
2. To protect local properties and aquatic resources located wholly or partly in an internally drained area Dane County should:
a. Develop an operational definition of internally drained areas and delineate internally drained areas in the county.
b. Require 100% on-site control of the average pre-development runoff volume based on average annual rainfall, regardless of the required effective area needed for the infiltration system. Use of fee in-lieu program credits would not be allowed in these areas, except for a site exempted by WDNR standards where a fee in lieu credit would be allowed to exceed the 10% gap between 90% and 100%.
c. Require provision of adequate storage within the internally drained area for the runoff volume from back-to-back 100-year 24-hr storms to define a flood protection elevation, and so that there is no increase in downstream flood risk during a 100-year event due to discharges from the internally drained area.
d. Require development of an emergency drawdown (pumping) plan to mitigate unanticipated local flooding.
e. Sites with stormwater management plans approved prior to the adoption of this ordinance should be exempted.
They also want people who can’t control the water on their land 100% to be able to buy their way out of it by trading with others who can do more to control the water on their land. They recommend this program:
1. Dane County should establish a county-wide volume trading/fee-in-lieu program to facilitate off-site volume control where on-site control would not be feasible, or would be inefficient or prohibited. This program:
a. Would be administered by the Dane County Land and Water Resources Department, with oversight provided by an external board. This external board should be convened as soon as possible to assist the County in designing the trading program.
b. Be based on site-based rainfall stay-on volumes calculated using the 1981 rainfall standard, and comprise one-to-one rainfall volume trades.
c. Shall not be used to meet the current 90% standard.
d. Would allow volume trading for re-development and exempted sites. (Trading would be allowed for sites where 2% of the site area is dedicated to infiltration. Once reaching the 2% area dedication, trading can be used to meet the remaining volume requirements.)
e. Require trading for sites where on-site controls are prohibited.
f. Allow trading involving both public and private parties, with county oversight.
g. Promote trading in locations with the greatest need for volume control, such as the Yahara Lakes watershed.
h. Set an initial cost per unit volume of runoff controlled, prior to the proposed ordinance changes being approved.
i. Identify a regional volume control facility to be implemented prior to
implementing fee in lieu for new and re-development.2. To reduce the stormwater volume impacts of past development, Dane County should consider capital projects and/or grant funding to facilitate the implementation of volume control practices in developed areas, and also in rural areas not subject to volume control regulations. In doing so, the County should especially take advantage of opportunities that would provide other benefits, such as phosphorus control or ecosystem restoration. It should be noted that if these county projects were used in the volume trading program, they would not reduce the volume impacts of past development. But they could reduce the flood risk from existing urbanized areas if their capacity exceeds the volume credits allocated to them.
3. Dane County should develop policies and procedures to facilitate the standardization of the design and installation of infiltration practices. These policies and procedures should recommend:
a. Use of WDNR technical standards for maximum area contributing to an infiltration practice.
b. Use of test pits to determine on-site soil characteristics.
c. Engineering supervision during the construction of infiltration facilities.
d. Post-construction performance evaluation of infiltration facilities.
4. The County should coordinate with local units of government that wish to manage their own stormwater programs by making available fee-in-lieu credits for County-managed regional volume control facilities. And, by acknowledging locally approved stay-on that meets the requirements of the ordinance.
5. Additional considerations for a stormwater volume trading program in Dane County:
a. Allow creation of rainfall volume credits from new infiltration practices, beyond those required by regulations, that result in reductions of stormwater volume discharge to any surface water body in Dane County.
b. Volume credits could be created by municipalities or private developers,
provided that they conform to the standards of, and are overseen by, the county-wide trading program. For example the calculated stay-on volumes could be certified and recorded by the Dane County Land and Water Resources Department.c. Volume control credits could accrue from new volume control practices within Dane County, or in areas outside of the County contributing runoff to a Dane County watershed (e.g. the Yahara River Watershed in Columbia County).
d. New volume control practices could be created for both new and re- development projects located in established urban areas.
e. It may be desirable that volume control credits for a practice be used in the major county watershed in which that practice is located (i.e. Yahara River Watershed, Koshkonong Creek Watershed, Upper Rock River Basin, Sugar- Pecatonica River Basin, or Wisconsin River Basin).
f. For each project producing volume credits a maintenance agreement that meets Dane County requirements could be recorded.
g. If at any future time the credited practice is modified in a way that reduces its performance, the county-wide trading program could obligate the landowner to provide replacement volume control or reimburse the value of the lost credits.
h. The advantages and disadvantages of municipalities managing their own volume control trading program (subject to County standards) should be explored, for example:
i. Would the managing entity be allowed to set the price of a volume credit?
ii. Would the revenue produced by granting volume credits accrue to the managing entity for use in their trading program?i. It may be advisable for construction to be completed on one or more volume control practices that would provide an aggregate stay-on volume adequate to provide the credits required to meet the expected development over the following 2-3 years.
j. If the demand for volume credits exceeds the availability from constructed practices, the volume trading program could provide credits in anticipation of new practices being implemented.
They also have recommendations for updates to the Dane County Stormwater Manual (Appendix V) and a Stormater Plan Checklist that needs to be completed as part of the development submittal.
What I can’t tell from the agenda is how much of this has been done, can be done, will be done? Perhaps that will be part of the presentation today?
TECHNINCAL WORK GROUP
Remember, when the flooding happened, one of the typical responses was to form a committee!! Here’s what the resolution passed on October 8th said . . . and this is the committee meeting today and that is why Sharon Corrigan (County Board Chair) will be there to remind them what they are supposed to be doing – making recommendations by March 31st.
ESTABLISHING A TECHNICAL WORK GROUP TO ADDRESS RECENT FLOODING IN THE YAHARA CHAIN OF LAKES
Climate change is increasing the frequency of wetter conditions, more severe storms and threats to public health, safety and public and private property. This summer storms have caused dramatic and unprecedented flooding damage across the County including historic high water levels on the Yahara Chain of Lakes and severe flooding in Madison’s Isthmus, resulting in financial damages exceeding $78,287,645 to residents and $37,114,219 to businesses with approximately only 2% of those damages insured. Lake levels for the Yahara Chain of Lakes (Mendota, Monona, Waubesa, Kegonsa) are managed by Dane County in accordance with Wisconsin Department of Natural Resources lake level orders developed in 1979.
Similar to flood events of 1993, 2000, and 2008, the events of 2018 call the questions of:
1. How to manage our lakes and reduce flooding with ever increasing volumes of water, mostly attributed to climate change and urban development;
2. How to improve the volume of water leaving the Yahara River system, a chain of impounded lakes connected by low gradient (relatively flat) river with obstructions by 31 bridges and railroad crossings, aquatic plants and sediment deposits; and
3. How to reduce stormwater runoff volumes through increased stormwater infiltration and better management of stormwater on impervious surfaces.
These questions must be asked within the larger context of the powers of the Wisconsin Department of Natural Resources (WI DNR) “to promote safety, and to protect life, health, property, property values, and economic values” and to “regulate and control the level and flow of water in all navigable waters…” (Chapter 31.02 Wis Stats).
NOW, THEREFORE BE IT RESOLVED, that the Land & Water Resources Department shall immediately convene a technical work group that may include representation from the University of Wisconsin and other experts to evaluate lake level conditions, model various scenarios that include predicted climate changes, identify short- and long-term approaches to improve resiliency for future events by February 1,2019.
BE IT FUTHER RESOLVED, that the Lakes and Watershed Commission in cooperation with the Environment Agriculture and Natural Resources Committee shall convene a task force to review the findings of the technical work group and make policy recommendations prior to March 31, 2019.
BE IT FURTHER RESOLVED, that the task force shall comply with the meeting requirements set forth in Chapter 7 of the Dane County Code ofOrdinances.
BE IT FURTHER RESOLVED, that Dane County will continue to prioritize the aggressive harvesting of aquatic plants, including native species, in the Yahara River to improve water flow through the system.
BE IT FURTHER RESOLVED, that, consistent with the Lake Level Management Guide that calls for attaining minimums in the fall and winter, Dane County will continue to implement any tools that may be available to lower lake levels to DNR designated minimum levels as soon as possible and work to maintain lakes at that level until the County Board acts on recommendations from the task force.
TECHNICAL WORK GROUP REPORT
So the staff made up of these folks below did the report – their deadline was February 1. And the Lakes and Watershed Commission and EANR (Environment, Agriculture and Natural Resources Committee) formed a new committee solely to look at this report.
Here’s the staff who did the report.
Technical Work Group Members:
Shelly Allness – WDNR, Policy Advisor
Jeremy Balousek – Dane County Land & Water Resources Department
Rob Davis – WDNR, Dam Safety
Greg Fries – City of Madison Engineering
Josh Harder – Dane County Land & Water Resources Department
Dick Lathrop – University of Wisconsin Madison, Limnology
Ken Potter – University of Wisconsin Madison, Civil & Environmental Engineering John Reimer – Dane County Land & Water Resources Department
Chin Wu – University of Wisconsin Madison, Civil & Environmental EngineeringOther Participants from WDNR:
Dan Oele (Fisheries Biologist)
Dave Rowe (Fishery Team Supervisor)
Travis Schroeder (Waterway and Wetland Supervisor) Wendy Peich (Waterway Regulation)
Eric Rortvedt (Stormwater Engineer)
Laura Bub (Runoff Management Field Supervisor)
Jim Amrhein (Water Quality Biologist)
Susan Graham (Aquatic Plant Management)
Mike Sorge (Water Resources Field Supervisor)
Jake Donar (Conservation Warden)
Andy Barta (DOT Liaison)
The group looked at doing the following options:
Adaptation
(a) Lower Lake Mendota one foot
(b) Safely Manage Lake Mendota at 100 year water level (c) Remove all dams from the Yahara Lakes
Mitigation
(a) Bridge Modification
(b) Yahara River Dredging
(c) Flow Reroute and Pumping
(d) Combined (b) and (c)
From looking at these scenarios, the staff group concluded:
• The adaptation scenarios of lowering Lake Mendota provided little benefit to flooding (less than 2”). The flows through the lower lakes are limiting efficient release of water and are still prone to flooding.
• The adaptation scenario of safely managing Lake Mendota to 100 year levels increases Mendota 6” to provide relief to the lower lakes by decreasing Monona levels 6” but at the risk of using available capacity for storage from future rainfalls.
• The adaptation scenario of removing the dams increased flood levels on the lower lakes (approximately 2”).
• The mitigation scenario of bridge modification provided little benefit overall (approximately 2”) to flooding as most improvements are gained during low water conditions.
• The mitigation scenarios of dredging and pumping produced the best results for lowering flood levels (ranging from 7” to 21”) especially when used in combination.
Remember, the committee was supposed to do a report that did the following
– evaluate lake level conditions,
– model various scenarios that include predicted climate changes,
– identify short- and long-term approaches to improve resiliency for future events
The report has lots of numbers and graphs and maps and chart and photos, so you should take a look.
LAYLADY’S TAKEAWAYS
Again, important disclosure: this is not my area of expertise whatsoever! However, I felt the need to get better informed since I haven’t really dealt with this in the past 10 years since I was an alder. This is what I could glean from the reports, in very layperson terms. For those of you in the same shoes as me, I figured you might appreciate what I found. You can read the reports yourself to get more details and all the technical speak. I’ve read lots of reports in my day, and here’s what I found to be of interest.
Basically we have a chain of lakes connected by rivers – starting in the north Mendota -> Monona -> Waubesa -> Kegonsa generally going from Madison -> Monona -> McFarland -> Stoughton. There are three dams, one at Tenney between Mendota and Menona Lakes. Babcock Dam at Lake Waubesa and LaFollette Dam at Lake Kegonsa.
The 7 of the top 10 flood levels of lakes Monona and Mendota have occurred in the past 25 of the last 103 years of data for the lakes.
The Yahara Lakes have summer minimum and maximum target lake level orders that were set by the Wisconsin Department of Natural Resources (DNR), per the request of the City of Madison and Dane County, in 1979 and can be found online at https://lwrd.countyofdane.com/Lake-Levels. The orders seek to balance competing interests, such as navigation, flood control, fisheries, and recreation.
This report also lists why there is flooding, and their list includes:
– Water not flowing out fast enough (narrow bridges, sediment deposits, debris in the river (tree trunks and boulders) and aquatic plants.
– Increase runoff due to development/urbanization
– – Increase in impervious surfaces
– Enhanced drainage of agricultural lands
– Loss of wetlands
– Increase in amount and intensity of rainfall
Babcock and Lafollette dams have been left completely open since August of 2016. Tenney Dam operates to make sure the lakes in the chain after it don’t rise above their maximum levels. The county got special permits to remove aquatic plant growth between Lafollette and Stoughton Dam to increase the flow. The county also removed sediment by the railroad trestle in Stoughton. Despite these efforts Lake Kegonsa was above its maximum level most of the summer.
They go into great detail about their modeling tool and method – you can read that if it’s of interest to you. I’d have no idea if they are bullshitting us or not about the effectiveness of their models and their results.
Results
Remember, the committee was supposed to do a report that did the following
– evaluate lake level conditions,
– model various scenarios that include predicted climate changes,
– identify short- and long-term approaches to improve resiliency for future events
And they said they tested
Adaptation
(a) Lower Lake Mendota one foot
(b) Safely Manage Lake Mendota at 100 year water level (c) Remove all dams from the Yahara Lakes
Mitigation
(a) Bridge Modification
(b) Yahara River Dredging
(c) Flow Reroute and Pumping
(d) Combined (b) and (c)
However, result 4.1 is “Aquatic Plant Management”? And then they say that if only they were allowed to use chemicals they could kill enough plants to have a good result, but without chemical, they can’t attain enough benefit.
4.2 Adaptation Scenarios
a. Lower Lake Mendota one foot
They say if they do this the downstream lakes will be over the summer maximums more often and could cause flooding in the lower lakes. They also say it would be hard to manage in years that are more wet. They say if they did this, they would have worse results than we did in 2018 with the lakes being above the summer range. This is their conclusions:
• Lowering Mendota 1 foot would require a petition to DNR which would require the consideration of other aspects such as fisheries, wetlands, recreation, navigation, social, and economics impacts.
• Lowering Mendota 1 foot shows that there would be more days above summer maximum levels for the other lakes besides Lake Mendota. Furthermore, additional slow no wake days in the summer months is likely.
• Lowering Mendota 1 foot in March potentially coincides with critical fish spawning, which could be a threat to a healthy fishery.
• Lowering Mendota 1 foot and using it as a storage reservoir produces larger water level fluctuations that could result in dislocating wetlands and impacts to state threatened species, such as Sheathed Pondweed, White Lady’s Slipper, and Tufted Bulrush.
• Other biological, social, ad ecological impacts are likely as well when managing lake levels.
b. Safely Manage Lake Mendota at 100 year water level
There is an odd fragment of a sentence here that says “Dam Breach Analysis safety” and some blank space.
Then, they says the same thing about flooding in the lower lakes and identify these issues
• This scenario shows that storing water on Lake Mendota can provide some benefit; however, once storage is used up, water will need to be released downstream potentially creating a future flood risk on Lake Mendota and/or downstream lakes.
c. Remove all dams from the Yahara Lakes (Tenney, Babcock, Lafollette and Stoughton)
This would require lowering Lake Mendota 4 feet and they don’t know how this would be achieved. These are their takeaways:
• Removal of Tenney Dam is likely to require a phase in period to lower the lake approximately 4 feet (for 2018) as it is unlikely to be accomplished over one year. Timing of drawdown is likely contingent upon expected wet and dry weather years and further study would be needed to determine lowering Lake Mendota.
• Removal of the dams eliminates the ability to retain water during dry periods.
• Removal would require permitting from the DNR as well as consideration for biological impacts.
4.3 Mitigation Scenarios
a Bridge Modifications
In this scenario, human made structures such as automobile bridges and railroad bridges are widened and assumed to free span with no pier supporting structures. In total there are 14 bridges widened which include all bridges from Lake Monona to Stoughton Dam. Also, no changes were made to deepen the river beyond its current water depth.
This was their takeaways:
• Bridge modifications would require coordination among several parties (State, Local, and Federal).
• Bridge modifications would require replacement of those that are not on current schedules to be replaced within the next 10 years due to their age and current funding obligations (except County Highway AB which is being replaced in 2019).
b Yahara River Dredging
The modeling assumed the Yahara River was dredged 50 feet wide ranging in depths of 2-3 feet. The total cubic yards of material removed from each of the Yahara River areas are approximately 50,000 cubic yards between Monona and Waubesa, 75,000 cubic yards between Waubesa and Kegonsa, and 150,000 cubic yards between Kegonsa and Stoughton.
The modeling results show that a large benefit in reducing water levels could be achieved from dredging. These were the takeaways from this scenario
• Dredging deeper than design may be considered to provide a longer life expectancy.
• Dredging in subsequent years may be required to maintain depth due to continued sedimentation that would limit flow capacity.
• Dredging the Yahara River could also benefit aquatic plant harvesting operations due to deeper water depths helpful for navigation and draft.
• Dredging the Yahara River would impact historical artifacts such as the Native American Fish Weir.
• Dredging may require bridge replacements if abutments or piers do not have proper support from sediment
• Dredging may require the purchase of land and/or easements for dewatering locations and hydraulic pipelines and sediment disposal. The acquisition of land may consider additional land to support future maintenance dredging.
• Dredging would require a permitting and approval process from DNR, including compliance with NR 150 and Chapter 30.
• Sediment sampling for contaminants would need to be completed to determine impacts to water quality and proper disposal methods of sediment which would impact project costs
• Further study is suggested to evaluate the feasibility of the project such as costs, dewatering locations, biological impacts, and construction techniques.
c Flow Reroute and Pumping
The technical work group identified two possible options of flow reroute and pumping. One option is to create a pipeline from Lake Waubesa to Lake Kegonsa and bypass Lower Mud Lake. A second option is deliver water out of the Yahara Lakes from Lake Waubesa to Badfish Creek
They conclude “The results show that Lake Monona does not show the greatest benefit as the remainder of the lakes mainly attributed to no improvements made in the connecting river from Lake Monona to Lake Waubesa.” and they identified these issues:
• Flow reroute and pumping would require a permitting and approval process from DNR.
• Flow reroute and pumping would require the purchase of land and/or permanent easements for pipelines and pump buildings.
• Flow reroute and pumping should be equipped with a Supervisory control and data acquisition (SCADA) system to record and regulate flow based on upstream lake levels and downstream levels (e.g. Badfish) to minimize flooding.
• Flow reroute could be designed for low water levels to discharge using gravity and during high water levels a pump would be utilized. Further study is suggested to optimize operational costs versus flooding.
• Further analysis and assessment is necessary for impacts to downstream flooding (i.e. flow from pump station may be limited based on water levels downstream).
• Further study is suggested to evaluate the feasibility of the project such as capital and operating costs, pump station siting, piping configuration, etc.
d Combined dredging and flow rerouting
While the previous results show individual benefits from each scenario, it is recognized that final solutions may be a combination of solutions. As an example, the top two benefits of dredging and pumping were selected to be used in combination. Specifically pumping was utilized as previously stated in section 3.7 and dredging was employed only between Lakes Monona and Waubesa.
5.0 Summary and Discussion
• Based on modeling the lakes for the period January through October, 2018, the adaptation scenarios of lowering Lake Mendota and removing the dams provided little benefit to flooding. In both of these scenarios, the flows through the lower lakes are limiting efficient release of water and are still prone to flooding.
• The adaptation strategy of safely managing Lake Mendota to 100 year levels provides relief to the lower lakes but at the risk of using available capacity for storage from future rainfalls.
• The mitigation scenario of removing constriction points provided little benefit overall to flooding as most improvements are gained during low water conditions.
• The mitigation scenarios of dredging and pumping produced the best results overall.
• The combination of dredging and pumping provided the largest benefit. This combination of mitigation scenarios delivered approximately 95,000 ac-feet per year by pumping water. The watershed area for the Yahara Lakes (subtracting out lake water surface area) is approximately 230,000 acres. As a result, the combination scenario would equate to storing approximately 5 inches spread evenly across the watershed. In other words, all land types such as roads, parking lots, rooftops, agriculture fields, wetlands, grasses would need to store and prevent runoff of 5 inches more water than in 2018 to equate to the mitigation scenario. For example, a 1⁄4 acre lot would need to store approximately 34,000 gallons of rain water. Figure 33 below provides a graphical representation to relate the increased delivery of water to the same amount water stored on land.
I’m not sure about you, but I feel like these options weren’t really made in good faith. It seems like they tested somewhat ridiculous scenarios and then said – “see, it just doesn’t work”. Maybe I’m just being cynical, but this report seems to be a bunch of flashy charts and graphs to lead people to the conclusion that there are no solutions and to make the report really long so no one will read it. Sigh . . . I am cynical.
Remember, the committee was supposed to do a report that did the following
– evaluate lake level conditions,
– model various scenarios that include predicted climate changes,
– identify short- and long-term approaches to improve resiliency for future events
I’m not sure they did. They were supposed to evaluate lake level conditions, but they say that the “focus in this report has been attributed to increasing river flow capacity” and then they point back to the previous report about stormwater.
The report then goes on to discuss what they’ve already provided for in the 2019 budget:
In 2019 the county budget includes new initiatives to improve stormwater impacts and reduce runoff. A study will be conducted to assess restoration of the Door Creek wetlands that were inundated with water through the summer, preventing worsening flood conditions for homes in the Towns of Dunn and Pleasant Springs. Door Creek is identified as a potential “Suck the Muck” location, and the study goals are intended to identify restoration of the Door Creek system that improves water quality, adds flood storage, and improves fish habitat. Also, a new Dane County Conservation Reserve (CRP) Program will be created to convert lands at greater risk of runoff to prairies and grasses, which are more able to hold soil and reduce water runoff. This Dane County CRP program ($750,000) will provide funding to farmers and property owners to convert lands to permanent cover for projects that reduce runoff and erosion. Furthermore, $8 million was added to the budget for conservation acquisitions with a goal of permanently securing properties that improve the county’s ability to reduce stormwater runoff and improve water quality. Lastly, Dane County supports an urban water quality grant program ($1 million added funding) offered to municipalities that apply for funding. New in 2019, the grant program will fund projects that provide stormwater volume control.
Also, the 2019 Dane County budget invests in strategies to improve flow in the Yahara River system. A new $2 million initiative is created to analyze and restore potential locations in the river where water flow may be constricted. Also, two new aquatic plant harvesters and a hydraulic crane that will mount to an existing barge will be added to the county’s fleet to improve removal of aquatic plants, trees and other large items of debris that restrict flow in the Yahara River. Currently, construction is underway to replace the Highway AB Bridge that crosses the Yahara River. As part of the construction, the pier depths are being modified to accommodate potential future dredging efforts in the river to improve water flow.
Lastly, the 2019 Dane County budget includes enhancing its emergency response capabilities. County government issued over 400,000 sandbags and deployed two sand-bagging machines during the August rains and subsequent flooding. The budget includes dollars to acquire three additional fast-fill sand bagging machines, another 250,000 sandbags, large pumps to move volumes of water off roads and other critical infrastructure, and portable generators that can keep services needed in an emergency situation when power is out. Also, a new airboat will be purchased to help with high water rescues. To ensure a seamless public safety response, a new web-based phone communication system will be acquired to assist the 911 Center. The budget also includes funds to provide emergency housing for those with special needs who are displaced or need to be moved from harm’s way in a short time frame.
Flood risk in Dane County has been increasing and will likely continue to increase unless vital actions are taken. The 2019 Dane County budget recognizes the need and proposes a total of over $18 million for investing in strategies that reduce risk and improve preparedness in the event of future flooding. As a community it is essential that all units of government including state, cities, villages, towns, and the county work together and invest in strategies that reduce risk and improve preparedness to future flooding. This goal of this report is to increase our awareness, improve our understanding, and provide possible scenarios to be resilient for future flooding for the Yahara River Chain of Lakes.
I interpret this to mean that they don’t want to do anything new or different than what they are already doing. That they are justifying the status quo and making it seem like they’ve done everything they can. I’m not buying it.
