Drawdown

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Drawdown

• Drawdown Sub Committee
• Mario Andella Melvin BertramPaula Bertram

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What is Drawdown?

• Drawdown is the lowering of water over the Autumn
  period to allow oxidation, desiccation and
  compaction of sediments. Plant growth is
  affected by freezing the roots, roots then rise
  and plants are unable to establish themselves.

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Advantages

• May reduce available nutrients or nutrient
  rations, affecting algal biomass and composition
• Opportunity for shoreline clean-up/structure
  repair
• Flood control utility
• May provide rooted plant control

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Disadvantages

• Possible impacts on non-target resources
• Possible impairment of water supply
• Alteration of downstream flows and winter water
  level
• May result in greater nutrient availability if
  flushing inadequate

5
Studies Recommended/Required

• According to Dominic Meringolo of Aquatic Control
  Technologies several reports/investigations would
  be needed to minimize impact to flora and fauna
  and to ensure that sufficient lake levels are
  maintained to promote healthy flora/fauna
  environment and to allow recreational uses.

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• Map showing water depths across the entire lake
  This could be done by a professional, or by the
  Lake Association using a gps sonar device
  depths are captured around the lake.
• Using the depth map professional would evaluate
  the hydrology of the lake to determine safe level
  of draw down and environmental impacts associated
  with drawdown. Things that will be taken into
  consideration
• Sufficient depths must be maintained to allow
  fish to overwater.
• Impacts to wetland growth must be considered.
• Impact to shallow wells and water supply would
  have to be evaluated (including public well at
  Woodlands).
• Important to understand hydrology budget for the
  water body to be certain that the water body will
  refill in a timely fashion.
• Depending on local conservation commission, a
  complete hydrology study may be required.

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Potential Reviewing Agencies

• Lunenburg Conservation Commission
• Shirley Conservation Commission
• Division of Fisheries and Wildlife
• DEP
• Nashua River Watershed Association

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Permitting

• According to Lee Lyman of Lycott, the State
  usually will permit a drawdown of 2 without
  difficulty, however anything more than 2 is an
  involved permit process. Currently the level of
  Hickory Hills lake is lowered in accordance with
  the recommendations of Dam Safety (approx. 16
  18).
• Lyman commented that the State would want
  documentation as to why substantial drawdown is
  required, he recommends a drawdown level of
  6-7to be effective. According to the Mass Lake
  Management handbook even an additional 12 of
  drawdown can be effective.
• Dominic Meringolo of Aquatic indicated that in
  his experience typically a permit from the local
  Conservation only is required.
• Lake Shirleys drawdown Program is permitted by
  the Lunenburg and Shirley Conservation
  Commissions in accordance with the Wetlands
  Protection Act.

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Permit Submittal Requirements in Accordance with
Wetland Protection Act

• Public and/or Private Water Supplies
  Determine any wells or water supply intakes which
  could dry up during a drawdown. Describe
  mitigation to be provide if water supply impacts
  are unavoidable.
• Rare Species Demonstrate the absence of
  rare wildlife habitat or that drawdown will not
  adversely effect the habitat if present.
• Fisheries Estimate area and depth zones to
  be dewatered. Verify the presence of a deep-water
  pool or other refuge areas with sufficient
  dissolved oxygen levels to prevent fish kills.
  Provide drawdown/refill dates, estimate of refill
  time, and estimated downstream flow rates during
  refill.
• Alternative Analysis The Applicant should
  consider all reasonable alternatives for
  controlling target plants and explain why
  drawdown (or drawdown used with other methods)
  was chosen.
• Control of Target Species Provide a map
  showing the distribution/density of target and
  non-target plants a list of target species to be
  reduced verification that target species would
  be reduced and, verification that target species
  would be dewatered.
• Dam/Outlet Control Structures Document
  maximum drawdown depth and evaluate the dams
  structural integrity to verify that it can
  withstand drawdown. Document the rate and
  duration of drawdown, and a contingency plan if
  the structure is stuck in an open position.

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• Water Quality Discuss potential project impacts
  to productivity, nutrient cycling, sediment
  inputs,
• and potential algal blooms. Address,
  sediment/erosion controls, removal of accumulated
  sediments
• prior to drawdown, and other measures to minimize
  potential for flushing nutrients and sediments
• downstream.
• Fisheries Discuss the potential positive and
  negative impacts to fish habitat, including
  downstream
• impacts to fisheries habitat resulting from low
  flows during refill. Provide estimated downstream
  flow
• rates during drawdown and refilling. Discuss the
  potential adverse impacts to freshwater shellfish
  species, including clams and crayfish.
• Wildlife Habitat Discuss potential impacts on
  small mammals, waterfowl, invertebrates,
  amphibians,
• and reptiles. These impacts may be related to the
  timing of the drawdown versus the start of
  hibernation
• or brumation periods and reductions in vegetation
  preferred by wildlife.
• Flood Control and Storm Damage Prevention Discuss
  the potential for downstream flooding
• during the drawdown and prevention of damage to
  public interests by flood waters or storms.
• Prevention of Pollution Discuss (1) the
  anticipated impact of drawdown on the
  productivity, nutrient
• cycling, sediment inputs and potential for algal
  blooms and (2) the potential for flushing
  nutrients,
• sediments and other pollutants to downstream
  lakes and ponds. A 401 Water Quality Certificate
  should

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Drawdown Schedule

• The drawdown schedule will be determined by the
  evaluation of surrounding flora/fauna and the
  hydrology of the water body.In general Lee
  Lyman of Lycott recommends a September/October
  drawdown (State recommends November 1st), and
  then starting the refilling process after the 1st
  hard freeze. Dominic Meringolo of Aquatic
  stressed that starting the re-fill process at the
  appropriate time is critical, additionally
  minimum flow has to be maintained to support
  flora/fauna.

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Lake Shirley Drawdown Program

• Lake Shirley has been using drawdown as a lake
  management technique for many years to control
  macophytes.
• 2002 NOI sought a 6 foot drawdown, drawdown
  request in 2005-2006 sought 9 drawdown
• 2006 NOI requests commencement of drawdown on
  October 8th at rate of 2 per day drawdown
  depth anticipated to be reached on November 25th

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Lake Shirley Drawdown Annual Reporting

• Annually the LSIC submits an Annual Drawdown
  Report to the Shirley Conservation Commission
  following drawdown in accordance with Shirley
  Order of Conditions
• Report is extensive contains information such as
• Summary of Process
• Graph of drawdown levels
• Monthly precipitation data
• Outflow Measurements
• Other Impacts
• Conclusions Recommendations

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Lake Shirley Costs (2006 Filing)

• Consultant Support Filing Fees - 2,000
• Data Gathering Hearing Appearances - 0
  (completed by LSIC Director) Important to note
  that Shirley has utilized drawdown for a number
  of years and had a great deal of studies and data
  available for NOI filings.
• Annual Vegetation Surveys - 3,000 each
• Outflow Measuring Program - 0 if setup by River
  Ways Program participation requires regular data
  gathering

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Expected Costs

• Drawdown is a relatively inexpensive lake
  management technique, if the means to conduct a
  drawdown are present. Where an outlet structure
  facilitates drawdown, the cost may be as little
  as what is required to obtain permits, open and
  close the discharge structure, and monitor. If
  pumps are
• required to lower the water level, the
  drawdown will be more expensive. It is unusual to
  alter a dam for less than 100,000, but if the
  structure already supports water level control,
  costs of 3,000 to 10,000 per year would be a
  reasonable expectation for permitting and
  monitoring. Where protected
• species are present, permitting may be
  difficult and monitoring and mitigation costs can
  escalate. (2004 Practical Guide)

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Areas for Further Investigation

• Integrity of sluice gate to be utilized for
  drawdown
• Details of existing limited drawdown program
• Compilation of existing reports and data

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Sources

• 2004 Practical Guide to Lake Management in
  Massachusetts, Executive Office of Environmental
  Affairs
• Aquatic Control Technologies http//www.aquaticcon
  troltech.com/physicaltreatments.html
• Geosyntec Consulting http//projects.geosyntec.com
  /NPSManual/Fact20Sheets/Lake20Level20Drawdown.p
  df
• Lycott Environmental http//www.lycott.com/drawdow
  n.html
• Carl Luck, Former LSIC Board of Director