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

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E. Fishery and hydrology studies conducted prior to the first enlargement of Black
Lake No, I found that the critical factor for trout populations in Gore Creek was limited adult
habitat due to low flows during the mid-winter months of January and February, Based upon
these findings, the Consolidated District and the Department entered into a second Memorandum
of Agreement dated March 1990 (the "1990 MOA"), that revised the operating procedures for
Black Lakes for a ten-year period, Under the revised operating plan, all 300 AF of the available
storage of Black Lakes was used to augment streamflows in Gore Creek during the months of
December through March, This operating plan was implemented in 1993 upon completion of the
first enlargement and has now expired,

F, The District is proposing a second enlargement of Black Lake No, I and
operational changes to provide additional water for District needs, including augmentation oflate
summer, fall, and winter streamflows in Gore Creek and the Eagle River, The proposed second
enlargement of Black Lake No, 1 would raise the reservoir surface elevation by approximately 4
feet, increase the capacity of the spillway, and utilize approximately 18 acre-feet of storage
below the currently established minimum pool (hereinafter the "Second Enlargement"), The
proposed Second Enlargement will involve the following actions:

i, The dam spillway will be enlarged from a 20-foot bottom width to a 40-
foot bottom width;

ii, A 4- foot high weir will be installed in the widened section ofthe spillway
to raise the surface elevation of the reservoir to 10,494,5 feet;

Ill. The dam crest will be raised by approximately 2 feet to an elevation of 10,
502.5 feet, using material removed from the spillway enlargement;

iv, The wheel house for control of the outlet valve,'the handicapped-
accessible fishing pier and path, piezometers and other appurtenances will be
modified as necessary to accommodate the increases in water surface and dam
crest elevations; and

v, The operating plan for the reservoir will be modified to make storage
water available to the District for other uses in addition to augmentation of
instream flows in Gore Creek during the fall and winter.

G, Since the completion of the first enlargement of Black Lake No, 1, the District has
planned and completed two major water supply system improvements that further reduce the
impacts of municipal water diversions on Gore Creek, The following improvements also provide
enhanced operational flexibility and reliability to the domestic water supply systems that serve
the Town of Vail and communities along the Eagle River below Gore Creek,

i, In 1995 the District completed construction of an interconnecting water
main between the Vail water supply system and the Upper Eagle Regional Water