PUB00108

• Year: 1986
• Title: St. Vrain Basin Reconnaissance Study
• CWCB Section: Administration
• Author: Colorado Water Resources and Power Development Authority
• Description: Extensive study for future study and development toward meeting the water-related needs of residents with the St. Vrain Basin
• Publications - Doc Type: Brochure

3. South St. Vrain Creek

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Button Rock Dam which creates Ralph Price Reservoi r is located on
North St. Vrain Creek, about 8 mi les upstream of Lyons. This reservoir has an
act ive storage capaci ty of 15,750 ac-ft and is the largest reservoi r in the
Study Area. Button Rock Dam was completed in 1969, and has a height of
210 feet. The dam was constructed by the Ci ty of Longmont to supplement its
municipal water supply as described in Chapter IV.

South St. Vrain Creek has a drainage area of 85 sq mi, including
Middle St. Vrain Creek, above its confluence with North St. Vrain Creek at
Lyons. Elevations in this subbasin range from approximately 5300 feet at
Lyons to 13223 feet at Mt. Audubon, near the Continental Divide. Middle
St. Vrain Creek has a drainage area of 31 sq mi and joins South St. Vrain
Creek at an elevation of 7040 feet, about 9 mi les upstream of Lyons.

Formerly, there were two USGS stream gaging stations on South
St. Vrain Creek. Station 7225, with a period of record from 1925 through
1927, 1929 through 1931, and 1955 through 1973, was located at about elevation
9400 feet, above the Left Hand Ditch Company diversion dam. Station 7234,
with a period of record from 1976 through 1980, was located above Lyons.

4. Left Hand Creek

Left Hand Creek, with a drainage area of approximately 72 sq mi,
has its source about 3 mi les southwest of the Town of Ward. Elevations in
this subbasin range from 4940 feet at the conf luence wi th St. Vrain Creek,
near Longmont, to over 11400 feet at Niwot Mountain. Left Hand Creek flows
are enhanced by importation of South St. Vrain Creek water by the Left Hand
Ditch Company, at a diversion point above the Town of Jamestown. An estimated
annual importation of approximately 12,000 ac-ft from South St. Vrain Creek is
included in the reported average annual Left Hand Creek discharge of
28,840 ac-ft shown in Table I I 1-1.

Previous Iy there have been two USGS stream gaging stat ions located
on Left Hand Creek. Station 7245, with a drainage area of 52 sq mi, was
located above the Left Hand Ditch Company ditch headgates. It operated off
and on from 1930 through 1980 when it was discontinued by the USGS.

Gaging Station 7250, located at the mouth of Left Hand Creek, was
in operation from 1928 through 1942 and from 1954 through 1955 when it was
discontinued by the USGS. At that time, it was reported that approximately
12,000 acres of land above this station were irrigated, indicating that gaged
flows are greatly affected by diversions and storage for irrigation.

5. Lower St. Vrain Creek

St. Vrain Creek between Lyon~ and the mouth, excluding Left Hand
Creek, has a drainage area of 201 sq mi. The water yield of this drainage
area is rather low in comparison to the mountain drainage basins, as average