Environmental Science ENSC 2800

1
Environmental Science ENSC 2800

• Spring 2003
• Classes 5 and 6
• The Bay Delta Issue 1
• Dams and Diversions

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The Hydrologic Cycle
3
Californias Water Balance

• On average, precipitation inputs some 200 million
  acre-feet (maf) of total water supply into
  California each year (an acre-foot is almost
  330,000 gallons).
• Some 65 of this, or around 130 maf returns to
  the atmosphere as evaporation or transpiration by
  plants.
• Annual runoff averages at 71 maf, more than 70
  of it occurring in the northern half of the
  State.
• The all time low runoff has been recorded as 15
  maf (1977) and the highest was more than 135 maf
  (1983).
• California imports an average of 7 maf from the
  Colorado river and Oregon portion of the Klamath
  river.
• Total water demand in the State is around 42.6
  maf.
• 11 of the runoff water goes to cities and
  industry, 43 to farmers, and 46 is left in the
  streams and rivers to flow out to the ocean or
  into inland sinks like the Salton Sea, Mono Lake
  (for more data, see DWR Water Plan Update 1998
  on line or hard copy).

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From the mountains to the valley
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California - dammed by human progress

• Click to go to online dam data base
• Shown are dams taller than 25 feet or larger than
  17m gals.

SOURCE Dams Within jurisdiction of the State of
California AUTHOR California Department of Water
Resources TYPE bulletin PUBLISHED June
1993 SERIES 17-93
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Diversions from the Delta

• Reservoir (dam) storage capacity in the
  Sacramento-San Joaquin system totals 30 maf, with
  storage equivalent to over 80 of the annual
  runoff in the Sacramento River basin and nearly
  140 of the San Joaquin River basin runoff
  (Kondolf, 2000).
• Diversions of Bay-Delta water occurs both within
  the Delta and upstream in the Estuarys
  watersheds to irrigate farmland and supply
  cities.
• In-Delta exports have largely remained within the
  range of 4 to 6 maf per year since 1974, but the
  percent of Delta inflow diverted can vary widely
  from year to year.
• The mean percentages of total Delta inflows
  diverted from within the Delta were 13 in 1997,
  10 in 1998 and 18 in 1999 (DWR).
• Total basin-wide diversions for consumptive (not
  returned) use reduce average flows to the Estuary
  by about 50 and seasonal flows in dry years by
  about 85 (Williams 2000).

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Note how the percentage of inflow diverted from
the Delta increases in periods with lower inflows.
1980-1999
From State of the Estuary 2000.
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Some Dam and Diversion Milestones

• 1850 Republic of California established and
  Office of Surveyor General begins water planning
  operations.
• 1860 Levee and reclamation districts
  established to prevent flooding and drain
  wetlands for farming/settlements.
• 1908 SF begins Hetch Hetchy project (completed
  1923).
• 1931 First CA State Water Plan published
  oriented toward conservation (as defined as
  putting water to use, not drainage to ocean).
• 1930s Many major federal dams begun by Army
  Corps of Engineers.
• 1933 Federal CVP Act passed and work begun on
  the system.
• 1951 CA authorizes beginning of SWP.
• 1950s Many major state dams begun to go with
  state water project.
• 1966 New Melones Dam begins construction last
  major project before environmental movement
  kicked in.

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A Plumbers Paradise
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Where does the water go?

• California's crops have a combined value of about
  30 billion per year, the highest total in the
  nation.
• Directly, this is only about 3 of California's
  trillion dollar economy, say 10 when all the
  related commercial activity is included.
• Irrigated agriculture in California uses over 80
  of the State's developed water supply to grow
  these crops.
• The largest users of water are the lowest value
  crops irrigated pasture uses almost as much
  water as all the cities in California put
  together (Its the Cheese!).
• Four low value crops irrigated pasture, alfalfa
  hay, cotton, and rice use about 40 of
  California's water, and by themselves add
  directly only about 0.25 to the state's overall
  economy.
• The only way California farmers can compete with
  external producers of such crops, widely grown
  elsewhere, is by having continued, cheap,
  subsidized water (Kolb 2000, DWR 1998).

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Californias Thirsty Cities

• As we have seen, California will add over 12
  million people to its population in the next
  twenty years, more than 20 million in the next
  50.
• Most of these will be added in the southern half
  of the state which has little water.
• The delta and its runoff is seen as a critical
  resource to support the California economy and
  facilitate its continued growth.
• Calls are heard for more dams, more diversions, a
  greater share of wet season runoff to be stored
  as carryover rather than be allowed to run
  through the natural system to the sea.

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Efficiency of use?

• Water use can be looked at from a variety of
  angles.
• Before we take any more water out of the Delta we
  must critically examine, for the farming,
  industrial and municipal sectors, what the water
  is used for, how it gets to where it is used, and
  how it is used once it gets there.
• In each of these areas we find inefficiencies or
  inappropriate technologies that are candidates
  for change and might obviate the need for more
  dams and diversions.
• Whether these are addressed is a function of
  politics and economics more than anything else.

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Typical use

• 1995 data show that the total average per capita
  urban use in California is 229 gallons per day.
  Out of that, around 120 gallons are used in and
  around the average residential home although in
  some parts of S. California, this is well over
  200 gallons per day per person.
• Irrigated crops have varying water needs from an
  additional 1-2 feet of applied water per year to
  as much as 10 feet (average rainfall is 23
  inches), e.g. pasture, alfalfa.
• Much of our irrigation technology is highly (75
  or more) inefficient.

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Chronically ill?

• In the State of the Estuary 2000 report, Phil
  Williams of PWA considers the SF Bay-Delta as if
  it were a human and the dams and diversions as
  causes of the following illnesses
• Arterial infarction (blocked heart vessels and
  arteries) dams impede the flow of creatures
  upstream and the movement of water and sediment
  downstream.
• Arteriosclerosis (hardened, narrowed arteries)
  riprapped and dredged channels, lack of floods,
  etc. all allow maximum use of the land to the
  waters edge and inhibit natural flow dynamics.

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More complaints.

• Hemophilia (frequent and chronic bleeding of
  water out) the lifeblood of the Delta
  hemmorages south.
• Atrial fibrillation (unnatural, erratic pulsed
  flows) the natural flood pulsing of rivers has
  been lost along with natures extremes.
• Anemia (reduced sediment in the water) the
  transport of sediment is essential to natural
  cycles and dynamic stability.
• All these conspire to make the system sick as
  defined by its loss of natural form and function
  and its inability to adequately repair and
  restore itself from past changes.
• Add to this intoxication from chemicals added to
  the water from agriculture, industry and urban
  runoff and we find a very sick system indeed.

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Schematic of Hydropower Dam
http//www.tva.gov/power/hydro.htm
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Lake Shasta HEP and Storage Dam
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Benefits of dams

• They produce hydropower they can do this
  without consuming much water, however, they do
  affect timing of flows and present barriers.
• They produce flood protection cutting out the
  big peak flows and allowing coordinated timing of
  water releases from different tributaries to main
  rivers to keep flows within bankfull limits
  again, more an issue of timing and fragmentation.
• They store and carryover water supply but water
  is not only stored, it is extracted from the
  system and sent to places where some or all of it
  will be subject to consumptive uses.

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Construction of Dams and Aqueducts Divert Fresh
Flows

• Dams create many different levels of impacts,
  both upstream and downstream, that affect
  migrating fish, several of which are now
  federally protected.
• Diversion via pumps within the Delta, is
  implicated in declines of fish species both
  because of physical removal of young fish by the
  pumps as well as habitat changes resulting from
  changing flow patterns and salinity distributions
  (USGS 2002).
• Sediment transport dynamics have been changed in
  complex ways and water quality is highly
  modified, due to reduced dilution capabilities
  and reduced flushing and counter-balance to tidal
  inflow.

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Changing Delta Morphology

• Between 1867 and 1887, approximately 115 million
  cubic meters of sediment was deposited in the
  Suisun Bay area.
• This is equivalent to about 2.5 cm/yr (1 inch)
  accumulation over all of Suisun Bay - most of
  this is debris from hydraulic gold mining in the
  Sierra Nevada and is contaminated with mercury
  used to extract gold from tailings. (USGS).
• Hydraulic mining ceased in 1884, while water
  distribution and flood control projects increased
  during the 20th century.
• These factors decreased the input of sediment to
  the Bay, and from 1887 to 1990 Suisun Bay was
  erosional (USGS) due to the creation of hungry
  waters caused by sediment being trapped behind
  dams.
• This sediment was thus shunted into the San
  Francisco Bay, much of it accumulating and some
  washing out under the Golden Gate.

21
USGS studies show past elevation changes along
the Delta
22
Recent changes show scouring and subsidence now
dominate the Delta
23
Large dams-flow/flood benefits

• Dams yield many downstream benefits because of
  the way they can control day-to-day, seasonal and
  multi-year flow volumes
• Dams can reduce peak flows and the risk of
  flooding downstream from overbank conditions.
• Dams can enhance flood flow forecasting and
  predictability by timing releases, especially on
  multi-dam river networks and when operated in
  series.
• Dams enhance dry season flows by their delayed
  release effect can be important for navigation,
  recreation, irrigation and so forth.
• Dams provide drought mitigation through carryover
  storage.

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Many Bay-Delta dams manage floods
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Dam Operation Basics
Flow Rate
qmax
Bankfull flow limit
May
Jan
Storage volume is retained behind dam to limit
flow past dam to below bank-full capacity of
downstream channels. Water could only be released
when flow falls below bank-full equivalent or
could be retained as carryover depending on
operation rules.
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Large dams-downstream effects

• Dams can have major negative effects that have
  frequently been ignored.
• Dams create hungry waters, producing a sediment
  deficit and creating a scouring effect on
  previously deposited alluvium and channel bed
  materials.
• Dams withhold nutrient flows and by eliminating
  seasonal flooding prevent floodplain enrichment
• Dams smooth out extreme events which are of
  critical importance in creating and maintaining
  habitat riparian vegetation, riffles and pools,
  sand banks, etc.
• Dams tame rivers, eliminating their wild and
  scenic nature.
• Dams block migrating salmon and other anadromous
  fishes in their movement up and down stream.
• Dams create false security downstream, since they
  cannot eliminate all flood potential and
  encourage intensive floodplain development for
  the 50-100 years, statistically speaking, before
  record-breaking critical runoff occurs.

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Migratory fish impacts

• Dams prevent fish movement up to spawning grounds
  and down to the Ocean.
• Dams destroy spawning grounds by inundation and
  upstream siltation.
• Dams and diversions change environmental
  conditions especially temperature, DO and
  turbidity but also chemical signals the fish
  might use to migrate e.g. pH.
• Dams change food supply dynamics, predation, etc.
• Dams and diversions change hydrology and thus
  indirectly change downstream vegetation, shade,
  cross-channel morphology and long-profile,
  salinity balances, flow directions and timing in
  estuaries, etc.

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Fish Ladders A mitigation? Too expensive to
retrofit.
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Some solutions?

• Allocate more water at critical times to
  maintaining optimal flows in streams and the
  Bay-Delta to permit maximum survival of returning
  adults and maximum success rates in reaching
  remaining spawning areas.
• Hauling of migrating adults from base of dams to
  above reservoir to improve reproductive potential
  of returning adults.
• Milking of captured adults at dam and hatchery
  raising (preserves genetics) to augment
  reproduction success artificially released
  below dam.
• Use of hatchery bred stock (dilutes genetics) to
  augment size of salmon fishery (release below
  base of dam).
• Capture of returning juveniles above dam and
  release downstream of dam to improve return
  probabilities of potential returnees.

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Conservation less dams, diversions

• Water conservation in California or in any other
  location is ultimately about efficiency
  achieving a particular goal with a minimum
  acceptable quantity of water.
• Conservation can be achieved by changes in
  operations, changes in technology used in those
  operations, and changing environmental conditions
  where those operations take place and the
  technology is employed.
• Whether conservation takes place is frequently a
  product of economics how much water costs with
  respect to the cost of changing operations,
  replacing technology or modifying environmental
  conditions, amortized over an appropriate
  discount period.
• In some situations, water use is relatively price
  inelastic, in other words, increases in the price
  of water will have very little impact on demand
  for it.
• This is usually the case where operations or
  technologies are not easily changed and the costs
  of reduced water use would be high.

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Why is water use an environmental concern?

• Using more water than is necessary for a
  particular purpose has many environmental
  consequences from exacerbated ecological impacts
  to greater resource depletion and corresponding
  environmental effects.
• Water resources, though variable over time, are
  finite in any period and thus we are dealing with
  a zero sum game every cubic meter of water
  removed from a stream or river is one less
  available for intrinsic, instream functions.
• Water delivered to a given location does not get
  there on its own, and it must frequently be
  processed prior to use the energy used in
  pumping, filtering, disinfecting or other
  delivery and treatment steps is enormous (plus
  chemicals and other inputs) and proportional to
  the volume delivered.
• Wasted or waste water similarly must be pumped
  and/or treated or the environmental impacts of
  lack of treatment must be incurred.

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Assessing conservation potential

• Evaluating conservation possibilities frequently
  involves a combination of engineering audits and
  economic analysis.
• Time and motion type studies are required to
  identify where and how water is used and why.
• Technological assessments are required to
  determine how and where changes can be made to
  reduce water use and any impacts on production or
  performance that might result.
• Economic analyses are required to analyze the
  costs and benefits of different changes versus
  the current system and establish benefit/cost
  ratios, internal rates of return, and so forth.
• Appropriate analytical procedures and
  mathematical tools must be applied to develop
  meaningful results.

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Residential water uses

• In California, generally landscaping uses 33
  (but can vary from 0 to 90) and indoor
  activities use 66.
• Interior uses break down approximately to toilets
  (36), bathing (28), laundry (20), misc. faucet
  use (13) and dishwashing (3).
• California average domestic consumption is around
  120 gallons per capita per day (gcd), 80 gcd
  inside, 40 gcd outside.
• Urban use per capita is doubled by the water we
  use in the workplace and that is used on our
  behalf by local government and other
  non-residential municipal users e.g. to irrigate
  our parks, wash our streets, put out our fires.

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Agricultural demand for water

• The demand for agriculture is principally a
  function of area of land cultivated, crop types,
  type of farming system, irrigation technology,
  irrigation efficiency, climate and soil type.
• In CA, around 9 of irrigated agriculture is by
  drip, 24 sprinkler and 67 furrow or flooding.
• Furrow irrigation is highly inefficient,
  resulting in more than 75 of the water being
  wasted as evaporation, deep seepage, or outflow
  to drains.
• However, water for most farmers is cheap,
  delivered subsidized by the state or federal
  government or pumped for a few cents per 1,000
  gallons from the ground or nearby river/canal.

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Urban conservation

• Conduct exterior and interior water audits and
  new facility design reviews to identify
  cost-effective savings.
• Promote efficient plumbing (new and retrofit)
  ULFTs, shower and faucet heads, front-loaders,
  etc.
• Require landscape water use standards for new
  installations drip, minimal turfgrass,
  xeriscape.
• Adopt conservation pricing (inclining rates and
  penalties).
• Increase public information and schools programs.

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Agricultural conservation

• Improve irrigation management (e.g. irrigate
  based on evapotranspiration calculations and/or
  soil humidity sensor data).
• Improve physical operations (e.g. line ditches
  reservoirs, capture return flows with pumps,
  install drip systems).
• Improve institutional arrangements (renegotiate
  contracts, provide loans, eliminate subsidies,
  educate farmers, etc.).