EPA: Frequent Questions on Removal of Obsolete Dams
“There is a growing awareness in the United States of the need to address obsolete dams that impair our waterways. Removal of these dams has been on the rise in the U.S. for a variety of reasons, including ecological restoration, economic development of communities, concerns with localized flooding, improvement of recreational opportunities, restoration of fish spawning and migration, and safety issues for recreational users due to dangerous hydraulics. In support of these efforts and in response to an increase in the number of inquiries regarding EPA policies, regulations, and potential funding opportunities as they relate to removal of obsolete dams, EPA is providing the following answers to frequent questions.”
Click HERE to read the full article.
Batavia Fox River Corridor Master Plan: Community Input Questions
Will the recording be available after the meeting?
A recording of the virtual open house meeting held on September 15, 2021 can be found on the City of Batavia Website , Batavia Park District website and on the Project Website.
If the dam is removed, will there be any river flow at all?
If the Batavia dam is removed and the upstream impoundment released, the Fox River will continue to flow at the same rate as it does currently below the existing dam, subject to natural fluctuation resulting from precipitation events, runoff, drought conditions, seasonal variation, etc. A hydrological study will be completed to determine the effect of the chosen concept on the flow of the river.
What will the height and width of the berm in relationship to the Riverwalk path?
The concepts are conceptual at this point, so they do not have precise dimensions.
How do our downstream neighbors (N aurora and aurora) feel about the impact to them from Batavia dam removal?
Neither entity have expressed any concerns to City staff.
Have you considered dredging the pond to be deep enough to have a fall turnover thereby self-cleansing and improving the health of the pond?
In Concept C, the pond will be excavated 6+ feet to maintain the same depth as current conditions. Any additional depth will be determined at preliminary engineering stage when more accurate geotechnical data is available and an estimate of cost for any additional dredging is calculated.
What is the upstream river impacts of dam removal?
In general, if the Batavia dam is removed entirely, the upstream impoundment will be released, and the river’s natural hydrology restored. Based on preliminary outcomes summarized in the alternatives report from 2000, it is anticipated the surface water elevation will lower approximately 6ft at the dam and reduce as you go north and normalize around Fabyan Parkway. A hydrological study of the upstream impacts will be completed once a preferred concept has been selected.
What is the current dredging frequency of the Depot Pond?
The Park District does not perform annual dredging of the Depot Pond.
Does the cost estimate for Concept A include dredging of the pond?
Routine dredging of Depot Pond is not included in the estimated cost for construction or in the annual maintenance estimate for Concept A.
In B, is it expected that water would always flow over the 6’ dam?
In Concept B, water is anticipated to flow over the northern most rock weir/dam as it does over the existing Batavia Dam today. The surface water drop at each of the rock weirs will be significantly less than the current elevation drop at the dam. It is expected to see natural fluctuation in water surface elevation and velocity over the rock weirs following precipitation events, runoff, drought conditions, seasonal variation, etc. as it does in the current condition with the dam in place.
What are these costs in relation to taxpayer impact per year? How much will it raises taxes per option?
The amounts listed below reflect the impacts IF the entire estimated costs were to be funded solely by City bonds. It is unknown at this time if additional grants could be secured or supplemented through other funding mechanisms to reduce or eliminate these costs, such as additional State funding, grants, partnerships, etc.
Cost per household listed below are based on a $300,000 median home value for a duration of 20 years with 2% interest on the debt.
A and D $20 for $4,500,000
C $30 for $6,500,000
B and E $67 for $13,500,000
What portion of the earlier engineering studies aren’t reliable at this point?
The design concepts and recreational use of the river still hold true. Biotic diversity/Fish species, and costs are most likely not reliable at this point.
In C, does the water still flow through the newly constituted pond like it does today?
In Concept C, the intent is to excavate the northern portion of Depot Pond to a depth that would maintain the surface water connection to the backwater channel of the Fox River following the removal of the Batavia Dam. The exact water depth and surface water elevation in Depot Pond will be refined following a hydrologic analysis of the upstream impacts of the dam removal, but it is unlikely that water would flow through the pond like it does today.
Do Concept C construction and/or maintenance costs include dredging, both now and in future?
The estimated construction costs for Concept C includes initial excavation of Depot Pond to maintain the surface water connection to the Fox River. Routine dredging of Depot Pond is not included in the estimated cost for annual maintenance estimate for Concept C as this is an ongoing maintenance activity that is currently performed by the Park District.
Option A: Would like some information in regard to the pump & motor system. Electrical utility costs to run the pump should be accounted. The big question is will depot pond and west channel hold water?
The Park District has information from 2002 summarizing their research of pumping systems for maintaining the water elevation in Depot Pond. This data was utilized as guidance for the development of the annual maintenance cost to operate and manage the system. A generalization on the size of a proposed pump was made for the conceptual alternative which included a 35 HP, 2250 gallons per minute pump. We have estimated annual pumping costs to be $35,000. We will not be sure Depot Pond will hold water without amending the existing soils to install a liner until a full geotechnical evaluation is performed.
What is impact of continued silt buildup in pond, step dam and bypass channel for future costs?
Routine dredging for the removal of sediment build-up in Depot Pond would need to be an ongoing maintenance cost in Concept E. The Batavia Park District does not currently dredge the Depot Pond and the City of Batavia does not currently dredge or excavate sediment build-up behind the existing Batavia Dam and would not be a new cost in Concept E where the current dam is modified to a step dam and bypass channel.
What is the native vegetation maintenance?
The purpose of native vegetation maintenance is to meet regulatory permit requirements and/or maintain the function and appearance of the native plant communities. This work may include but not limited to native seeding and planting, mowing, herbicide application, and prescribed burns to control the spread of weedy, non-native, and invasive species while promoting the establishment of high-quality conservative species. Vegetation monitoring may also be required to meet regulatory permit requirements including floristic quality assessments and preparation of annual monitoring reports that documents the annual native vegetation monitoring completed and recommendations for future management.
We are currently in a very low flow condition for the Fox River, ~ 400 CFS. Recently we had some very high flow, ~ 10,00 CFS. How will these options be able to handle this high flow/flood condition?
The selected concept will be studied for impacts during low and high flow conditions.
Lacey Lawrence mentioned several times in the first two options “dredging costs” to maintain the depot pond, what are those annually?
Preliminary estimates for dredging Depot Pond total $800,000. The frequency of dredging is driven by the amount of accumulated sediment that needs to be removed, for a closed pond system that could be every 20-years and potentially more frequent for an open system the is continually receiving sediment from upstream waterways.
Any option that builds a new dam becomes a new piece of infrastructure we’ll have to maintain over and over, so you’ll need to keep that in mind with each of the costs of anything with a dam for long term capital planning. I would like that estimate of length of time and replacement schedule included for each that depicts a dam or berm, which is just a dam.
It is intended that what is constructed as a result of this project is of a similarly permanent nature as the existing dam with associated ongoing maintenance costs. As the preferred concept is advanced through preliminary and final engineering in partnership with IDNR, annual maintenance costs will be refined.
How do boundaries change when Fox goes flood stage?
A hydrologic study of the selected concept will be modeled for impacts at various precipitation frequency and duration. Following construction, a Letter of Map Amendment/Revision may be requested from the Federal Emergency Management Agency (FEMA) for concepts that alter Special Flood Hazard Areas (SFHA) to be above or below the Base Flood Elevation (BFE).
I am under the impression that release of non-toxic silt is no longer viewed as pollution. Is this correct and if not, are costs of removing silt and/or holding it for release over time included?
Silt that is expected to be released downstream with the removal of the dam will be tested to determine its potential effect downstream. Based on previous studies we have no reason to suspect that it will need to be removed and since those studies were conducted there have only been more stringent environmental controls put in place on what can be discharged into the waterway.
Do you anticipate 404 or 401 impacts and if so, will mitigation be done within the 2 mile corridor or off-site?
Each of the proposed concepts require some amount of dredged and/or fill material placement in the Fox River with either an earthen berm, rock weirs, bypass channel, and/or installation of in-stream habitat structures i.e., pools, riffles, and boulders. Permits will be obtained through the U.S. Army Corps of Engineers (USACE) as part of the Clean Water Act Section 404 and/or Section 401 regulatory review process.
It is anticipated that mitigation for impacts will be constructed within the 2-mile corridor. I also want to know if the berm is accessible by bikes or walkers? That would be a bad thing if people could bike over it and then access the River WALK and cause safety issues with walkers.
At this point, the focus of the study is how the land and water will be configured. There are no plans for recreational improvements on new land spaces that may be created. This issue should be addressed in those future planning discussions if Option A is selected.
How will survey results be shared with the community?
Survey result will be available on the project website within 2 weeks of the end of the survey period which is October 1.
Can you put the link to the survey in the chat?
Click Here to Take the Survey
I believe the IDNR report found that the water elevation up stream would change north of the Fabyan island area. Could you comment on this or verify how far north the elevation would change if the dam were removed or if mother nature removes it for us?
We do not know the full extent of the impacts to water surface elevation upstream of the dam following removal at this time. Once a concept is selected a hydrological study and modeling will be done to determine this. Based on preliminary outcomes summarized in the alternatives report from 2000, it is anticipated the surface water elevation will lower approximately 6ft at the dam and reduce as you go north and normalize around Fabyan Parkway.
Is the cost to stabilize the Depot Pond retention wall included in any of these or is that separate? Please indicate that. The blocks could be reused for C. to move the pond edge north.
If a concept is selected that does not require moving the boundaries of the Depot Pond retaining wall then no pond wall stabilization costs were included in that concept. It is unknown whether the same block could be reused if the wall of the pond changes configuration, but we can certainly try to do so if feasible to reduce the cost.
How have impacts to property values been considered?
Several property owners have expressed their concerns about this issue and the City Council and Park Board as they considered which concepts to put forth for public comment. Likewise, when the matter comes back to these bodies for a final decision, these concerns will be part of the discussion.
Economy/Brand was called out as an input criterion. Can this be expanded upon to demonstrate this aspect as it relates to the options?
This relates to the extent to which a particular concept is expected to attract visitors to Batavia that would then add to the local economy.
When will you reveal the parameters considered to calculate the costs of each alternative?
Hitchcock Design Group provided itemized cost calculations for each of the five concepts at the joint meeting of the Park Board and City Council on August 3 which you can view here: https://youtu.be/Yj3weChBApI
Part of the South Batavia Dam was removed a few years ago. What was learned about the hydraulics of the Fox River and were the results in streamflow and remaining ponding as expected? Or were there unexpected new problems?
This information is not readily available. In an effort to get this document posted as soon as possible we will publish this without a response but will update the Q&A document once we have completed our research.
Is there a set of benefits that have been considered in cost benefit analysis?
There is a chart at the top of each concept which lists benefits that particular concept provides.
Will the City and Park District propose a funding mechanism for each option before a decision is made?
It is anticipated that the City and Park District will discuss funding in conjunction with their discussion about which concept will ultimately be selected.
How would these plans be impacted whether our neighbors to the north and south remove their dams or not?
We do not anticipate that removal of these dams will have any effect on our plans.
The West channel and depot pond was once a free-flowing part of the fox river as a 2nd leg before the dam was constructed. How can we protect this natural aquatic ecosystem with all these options?
The west leg you refer to was actually a manmade channel created to increase the number of businesses that could make use of it. It was later filled back in to create space for additional development in the downtown.
Is this a done deal? Are we moving ahead with one of these choices? How are we paying for this project?
A concept has not been selected. The City and the Park District are hosting these open house meetings to give the public the opportunity to learn about the concepts and provide comment on their preferences prior to a final decision being made. It has not been determined how the project will be paid for, but the Illinois Department of Natural Resources currently has a funded program for removal of low head dams and Batavia has the opportunity to apply for a grant of up to $3 million to pay for engineering and construction costs to remove the dam and stabilize the adjacent riverbank. The balance of the project would likely be paid for through the issuance of bonds that would be paid for using property taxes.
How many people attended this presentation?
A little over 200 people registered and about 170 people attended.
Will this project end up as a referendum?
Most likely, this project will not end up as a referendum.
What date was the first meeting regarding this topic between the City of Batavia and Hitchcock?
No timeline has been determined. The timeline is dependent on which concept is selected and how the project will be funded.
How has climate change affected the 2000 engineering study? How reliable is that right now since it has been 21 years.
It is likely that climate change has had an effect on that prior engineering study. New engineering studies are contemplated once a concept has been selected.
For Option A what is the difference of the current river width vs. the new width of the river?
Once a concept is selected a hydrological study and modeling will be done to answer that question.
Is an option to allow the dam to continue as is and let the slow decline of the dam?
Due to the rate of deterioration of the existing dam, the life and safety hazards it presents and the availability of up to $3 million in state funding to assist with the project, the City and Park District have decided to be proactive and plan for a concept rather than wait until the dam fails naturally.
Can the existing dam be modified into a step dam without it being fully removed?
Concept E proposes installation of a step dam in the location of the existing dam. If this concept is selected to advance to preliminary and final engineering in partnership with IDNR, the existing dam will be evaluated to determine if it can be modified or require removal for the installation of a step dam.
Will input of Kane County Forest Preserve be solicited as some of the concepts will impact lands north of Fabyan Parkway?
We have met with Kane County Forest Preserve District and asked for their input. We intend to meet with them throughout the process.
How can we be expected to vote on an option when we don’t know the upstream ramifications of the various options?
It would be cost prohibitive to pay for hydrological studies and modeling for five different concepts. Once a concept is selected, these studies will be conducted and if the analysis reveals negative consequences, the City and Park District can decide to select a different concept. Based on preliminary outcomes summarized in the alternatives report from 2000, it is anticipated the surface water elevation will lower approximately 6ft at the dam and reduce as you go north and normalize around Fabyan Parkway.
When the Wilson bridge was re-built, a large amount of gravel was left in the river and eventually moved downstream. Will that problem reoccur with any of these options?
We would not follow the same process to remove a coffer dam in the future.
Rather than a stepped dam in 1.5-foot increments, why not use more and smaller steps? Could you start the steps downstream of the existing dam that might reduce the size or need for a berm along Duck Island. These smaller steps could also incorporate the bypass channel in the middle for canoe passage.
More steps increase the costs of what are already the most expensive options. The planned steps/rock weirs in Concept B include construction of a low-flow channel through the center allowing canoe and kayak passage. Based on evaluations made during the development of the alternatives report in 2000, installing a series of steps/rock weirs downstream of the existing dam rather that upstream would result in flooding of the retirement community that is located adjacent to the dam.
When was the last time that Depot Pond was dredged?
The last time the Depot Pond was dredged was in 1995.
Completion time frame for part 1? Then for 2?
No timeframes have been completed for any of the concepts and they are dependent upon when the Illinois Department of Resources is able to allocate resources for the removal of the Batavia Dam.
What is the current annual cost of the maintenance of the dam/pond per “average” Batavia homeowner/taxpayer and what will the costs be (per taxpayer) for each of the 5 options?
For many years ownership of the dam was in dispute between the City and State of Illinois. The dam was in its current state of disrepair when it was determined that the City did indeed own the dam. IDNR has informed the City that it would not permit the any major repairs to the dam and that the only option moving forward is to remove it. Beyond installation of recommended safety signage and lighting, the City does not perform any maintenance on the dam itself. Likewise, there is no annual maintenance cost for the Depot Pond. The future maintenance of whatever concept is selected will certainly be an important consideration.
Can you avoid the pump by dredging deep enough to get the fall turnover such as 15’+?
No because you would then have very steep walls and a deep depression that would not resemble the lake level pond that exists today.
What happens to the current Riverwalk area if the pond is eliminated in concept C & D? What would be the cost to build a “park?” The numbers seem to be misleading. Has anyone put numbers to the loss revenues of business in the Downtown if the pond with its ambiance goes away?
The current Riverwalk area would remain. The cost of adding green space has been included in the cost of those concepts but any amenities that might be added to the new greenspace have not because that has not been decided. This fact is included in the description of these concepts so there is no intent to be misleading about that. As to your final question, that would be difficult to calculate, just as the potential increase to business revenue that might be created because of new amenities is also difficult to predict.
Can you talk about the impact on flat water (non-whitewater) recreation opportunities of the various concepts? I’m thinking about friendliness and safety for families in canoes and kayaks.
Safety and accessibility are concerns in the decision of which concept will be selected. Recreation opportunities will be evaluated following selection of a concept for the Batavia Dam and Depot Pond adjustments.
If the pond is closed off in opt A, will it need aeration systems to keep it clean?
Due to the water exchange created by the pumping system it is not contemplated that the pond will need aeration but that will be further evaluated if this option is selected.
What does native vegetation include? is that focused to include for the birds… fish and beaver.
Native plants are those that occur naturally in a region in which they evolved. This group of plants are specifically suited to the local climate, hydrologic regime, provide vital habitat and essential food for birds and other wildlife, and require less supplemental watering once established. Specific native plant species can be selected based on their unique symbiotic relationship with certain wildlife species.
Fox river study group has said that with a dam removal and with option c, d or a will only provide 1-3 feet of water depth. Water paddling recreation would not be feasible. I would hope this could be figured out before an option is picked.
Once a concept has been selected, a hydrological study and modeling will be done to determine resulting water depths. We will reach out to the Fox River Study Group to discuss their data prior to providing a more detailed response to this question.
I think we all are wondering, if the dam is removed, will our Batavia Fox River become a creek?
Once a concept has been selected, a hydrological study and modeling will be completed to determine the effect on the width of the river. Removing the dam will release the impoundment upstream of the same, the same volume of water will continue to flow through the river segment as did prior to the removal.
Will the community be shown before and after photos of dam removals where native vegetation was the result?
Below are two project examples, the first at Ryerson Woods Dam in Cook County and the second at Warrenville Dam in DuPage County.