Arkansas Basin_Water Supply and Needs

• Basin Roundtable: Arkansas
• Title: Water Supply & Needs Report for the Arkansas Basin
• Date: 6/1/2006
• Author: CDM
• Basin Roundtables - Doc Type: Needs Assessment Documents

Section 6
Non-Consumptive Water Supply Needs in the Arkansas Basin
-I

"... recognizes recreation values on Turquoise Lake and
will minimize draw-down during the June 15th through
September 15th period. Efforts will be made to maintain
a minimum pool elevation of 9,835 feet during this
period; however, project needs could dictate further
lowering. A minimum pool at elevation 9,776 feet will be
maintained for fish habitat and aesthetic purposes." An
elevation of 9,835 feet is a target level and equals
reservoir contents of 72,505 AF, and an elevation of
9,776 feet equals contents of 9,348 AF (Smith and Hill
2000 pp. 3-63). A Memorandum of Agreement (MOA)
was executed with the USFS on April 12, 1984,
concerning the transfer of lands acquired by BOR to
USFS at Twin Lakes. A provision of the MOA states that
BOR "... recognizes public recreation values of Twin
Lakes and will attempt to optimize reservoir surface
elevations for all reclamation project purposes including
public recreation. A minimum pool at elevation
9,168.7 feet will be maintained for power purposes which
should enhance the fish habitat and visual resources."
An elevation of 9,168.7 feet equals reservoir contents of
72,938 AF (Smith and Hill 2000 pp. 3-63).

Water ExchanQes
Water exchanges are used as a management tool for
municipal water supplies in the Arkansas Basin. A water
exchange is made by diverting water at one location in
the river system and replacing it with a like quantity of
water at another location. During an exchange,
streamflow in the reach between the two exchange
locations is decreased by the amount of the exchange.

Exchanges are often limited in these operations; for
example, the transmountain return-flow exchange for
Colorado Springs and the Rocky Ford Ditch exchange for
Aurora are restricted by several legal or voluntary
stipulations (Lewis 1999):

. The exchanges must be operated to maintain
streamflow in the Arkansas River so as not to
interfere with the operation of the Salida wastewater
treatment plant and the Fremont Sanitation District
wastewater treatment plant. Specifically, the
exchanges may not decrease streamflow at the
Salida wastewater treatment plant to less than 240 cfs
in September through June or to less than 260 cfs in
July and August. Exchanges may not decrease
streamflow at the outfall of the Fremont Sanitation
District wastewater treatment plant to less than
190 cfs throughout the year.

CDIVI

6-2

. Exchanges into Twin Lakes Reservoir may not
diminish streamflow in Lake Creek downstream from
Twin Lakes Reservoir to the confluence with the
Arkansas River to less than a minimum instream flow
of 15 cfs, as mandated by the CWCB.

Voluntarv Flow ManaGement ProGram
In 1990, BOR and the DNR signed an agreement under
which BOR would attempt to provide flows to better
support natural resource values. There is no legal
obligation upon BOR to provide the flows, and the
program must be operated within the context of legally
required storage and deliveries for water users. DNR
makes flow recommendations via an annual letter to
BOR each spring. The DNR flow management goals as
of July 2000 for the Arkansas River at Wellsville are
outlined below (Smith and Hill 2000):

. The highest priority is the maintenance of a minimum
year-round flow of at least 250 cfs to protect the
fishery.

. Winter incubation flows (mid-November through April)
should be maintained at a level of not more than
5 inches below river height during the spawning
period (October 15 to November 15) to protect and
incubate brown trout eggs. The optimum flow range is
from 250 to 400 cfs, depending on spawning flows,
which range from 300 up to 700 cfs.

. To the extent possible, between April 1 and May 15,
BOR should maintain flows within the range of 250 to
400 cfs in order to provide conditions favorable to
trout egg hatching and fry emergence.

. Deliveries in excess of 10,000 AF should be subject
to review and consideration, prior to such deliveries,
by BOR and the Southeastern Colorado Water
Conservancy District (SECWCD).

. Subject to water availability, BOR should augment
flows during the July 1 to August 15 period to 700 cfs
to support river rafting through releases from the
Fry-Ark Project. Aug mentation water may be
"recaptured" in Pueblo Reservoir for use by Fry-Ark
users. The 700 cfs level is a target; when
augmentation occurs, every effort should be made to
ensure that flows are as little above, or as little below,
700 cfs as possible. The Colorado Department of
Parks and Outdoor Recreation (CDPOR), using funds
collected from commercial outfitters, shall be
responsible for replacing evaporative losses caused
by summer augmentation.

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