The Colorado River

1
The Colorado River

• While looming large in our minds, the Colorado
  River is only a medium-sized river by world
  standards, generating some 15 maf of runoff per
  year over its 1,440 mile length from the
  mountains above Denver to Mexico and the Gulf of
  California.
• Most years, the Colorado now dries up before ever
  reaching the Gulf, creating tremendous changes in
  its delta and historic floodplain and wetland
  areas.
• The river carries some 9m tons of salt in its
  waters due to natural leaching, and the
  aggravating effects of salts flushed off
  irrigated fields (37) and reservoir evaporation
  (12).

2
The Colorado Compact

• The Colorado River was divided between seven
  states (and Mexico) in 1922 to meet flood control
  needs, irrigate dry but productive croplands,
  supply new industrial growth, and provide
  hydropower to the Wests booming metropoli.
• Parties to the compact were Colorado, Wyoming,
  Utah, New Mexico, Arizona, Nevada California.
• Led by Herbert Hoover, the Colorado Compact
  (which created the Colorado River Commission)
  provided what was believed to be an equitable
  division and apportionment of the use of the
  water.
• The compact was ratified in 1929 (1944 for Az)

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The pie that looked bigger than it was

• The division considered the Colorado watershed as
  having two parts - the upper and lower basins.
• Scientists convinced statess representatives
  that the Colorado carried more water than would
  prove to be available in an average year and
  during droughts (they expected 20-21 rather than
  the actual 15 maf).
• Demand projections did not envisage such
  phenomenal growth in residential, industrial and
  recreational development nor the problems
  resulting from irrigation of heavily saline
  soils raising downstream salinity from return
  flows and requiring excessive water for flushing.

5
The Law of the River

• The Colorado Compact is part of a larger body of
  legislation, agreements and court cases called
  the law of the river that regulate the use of
  Colorado River water among the seven states,
  Native American Tribes and Mexico.
• This includes the Boulder Canyon Project Act
  (Hoover Dam, All-American Canal), Mexican Water
  Treaty, Upper Colorado River Basin Compact,
  Colorado River Storage Project Act, Arizona v.
  California Supreme Court decision, Colorado River
  Basin Project Act (CAP), Minute 242 of the
  International Boundary and Water Commission, etc.

6
Dividing the Waters

• The Compact requires Upper Basin States (where
  most runoff is generated) to allow 75 maf per
  10-year period to flow to the Lower Basin, an
  average of 7.5 maf/yr for beneficial, consumptive
  use.
• Beneficial, consumptive use is not defined in the
  Compact, leading to debate over whether water can
  legally be marketed between states or transferred
  to other basins for use therein.
• Similarly, the Compact does not deal with water
  quality and therefore has few mechanisms to deal
  with the issue of increased salinity because of
  consumptive uses and inefficient irrigation.

7
Cracks in the Compact

• Upstream states have historically not taken all
  their allotted water, allowing California to take
  extra unused water (and to get used to doing
  so!).
• Downstream states now routinely use their full
  legal apportionment each year and more.
• Las Vegas growth is rapidly causing Nevada to
  take more, and soon all of its allotted share.
• Environmental and whitewater rafting groups are
  clamoring for greater releases from dams and
  therefore less storage for states appropriation.
• Supreme Court rulings can limit California supply
  to 4.4. maf - it is used to taking more than 5
  maf.

8
Mexico-who, how much, what quality?

• An unresolved question is how much water Upper
  Basin states must release - 7.5 maf/yr, 7.5maf/yr
  plus conveyance losses, or these plus the 1.5 maf
  promised to Mexico in the 1944 Mexican Water
  Treaty?
• A second question is what quality should that
  water be?
• Some 400 m has been spent on salinity reduction
  programs for the river and these now cost some
  20m to run each year with salt removal costing
  around 25-75 per ton.
• The federal government has built a huge desalting
  plant at Yuma, Az to clean up river water before
  it runs into Mexico but this has not been
  operated.
• As supplies are stretched, the issue of Mexicos
  water will become a critical one.

9
Heavily Dammed

• The Colorado River is one of the most heavily
  dammed (some say damned) river in the world.
• Major dams include the Glen Canyon, Hoover,
  Parker and Imperial but there are many smaller
  dams.
• The Sierra Club lost the battle over Glen Canyon
  dam but successfully prevented the USBR from
  damming the Grand Canyon itself.
• It is suspected that many of these dams are
  filling up with sediment at a rapid rate,
  especially Glen Canyon and worries still exist
  that failure could occur if extreme flood
  conditions are experienced.
• It seems inconceivable that these large
  structures, which can be seen from space, would
  ever be taken down but they could be operated
  differently to enhance instream flows.

10
Environmental issues flare up

• In the gung-ho years of conservation and
  exploitation, emphasis was develop the river,
  develop the land.
• Now conservation means not using, emphasis is on
  environmental and recreational releases and not
  consumptive withdrawals, power maximization and
  carryover storage.
• Environmentalists demand flood-intensity releases
  to destroy and rebuild sedimentary structures
  that promote aquatic life.
• Rafters demand releases to recreate whitewater
  rapids demanded by thrill-seekers.
• The ESA calls for releases to restore four
  endangered native fish populations - two chub, a
  sucker and a squawfish.

11
Native American water rights

• A 1908 Supreme Court Decision (Winters Doctrine)
  predated the Colorado Compact and holds that all
  federal American Indian reservations carry an
  implied and unquantified right to water
  sufficient for the reasons for which the
  reservation was created.
• How much water should the tribes get was and has
  never been quantified and remains unresolved
  today - the Navajo Nation could claim some 5
  maf/yr!
• Tribes could conceivably develop consumptive
  water uses such as irrigation or could decide to
  take and market water currently extracted for
  free by Lower Basin states (although the legality
  is in ?).

12
Californias Colorado water

• In California, Colorado water goes to seven
  entities Imperial Irrigation District, Palo
  Verde ID, Coachella Valley Water District,
  Metropolitan WD, LA Dept. of Water and Power, and
  the City and County of San Diego, all in the
  south, and they provide a portion to the Yuma
  reservation.
• Three of the entities (IID, PVID, CVWD) and the
  Yuma reservation have collective rights to 3.85
  of CAs 4.4 maf but no set allocation was ever
  determined.
• No accurate data is available on actual water use
  and controversy exists over IID efforts to
  conserve water and sell the savings to other
  agencies like MWD and SDCWA.