BOARD02105

• Board Meeting Date: 5/23/2005
• Description: ISF Section - MOA Between the Eagle River Water & Sanitation District and the Colorado Department of Natural Resources
• Board Meetings - Doc Type: Memo

Proposal to Enlarge Black Lake No, I

March 2005
Page 5

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Figure 3 illustrates the impact of current Black Lakes operations during 2000 through
2003 on streamflows in Gore Creek below the District's wells and below the diversion
for the Vail Golf Course (about 12 miles downstream from Black Lake No, 2), At this
location, diversions to storage during the spring are barely visible on the hydrograph
because of the large amount of tributary inflows below Black Lakes during spring runoff,
Reservoir releases during the winters of 200 I and 2002 were not sufficient to maintain
the 6 cfs instream flow, Under the currently effective operating agreement, no water was.
available for release during late September of2001 and August and September of2002
when flows dropped well below the CWCB 16 cfs instream flow,

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Figure 3: Gore Creek below ERWSD Wells and
Vail Golf Course Diversion - Current Conditions

The instream flow shortages shown in Figure 3 illustrate the District's need for additional
in-basin storage and for more operational flexibility to allow storage releases when
needed for both augmentation and instream flow purposes, Whenever the District can
use in.basin sources of augmentation (i.e, Black Lakes instead of Green Mountain
Reservoir) for water rights that are junior to Shoshone, it will be beneficial to the
instream flows in Gore Creek and the Eagle River below the mouth of Gore Creek.

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Because the 300 acre.feet of storage currently available in Black Lake No, I is not
sufficient to fully meet the District's augmentation and instream flow needs, the District
has continued to plan and develop other water supply system improvements to reduce the
impacts of water diversions on Gore Creek. In 1995, the District completed construction
of an interconnecting water main between the Vail water supply system and the Upper
Eagle Regional Water Authority system, This connection allows the District to divert
water from the Eagle River below Gore Creek, reducing the demand for pumping from

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