SPDSS_Task5_KeyStructure_LeftHandDitch

• Title: SPDSS Task 5 - Key Structure, Left Hand Ditch System
• Description: The Left Hand Ditch System has been identified as a key structure for the South Platte Decision Support System ‎(SPDSS)‎ consumptive use and surface water modeling efforts. The purpose of this Task 5 memorandum is to document physical, legal, and operational aspects of those key structures identified.
• Decision Support - Doc Type: Task Memorandum
• Date: 1/5/2005
• DSS Category: Surface Water
• DSS: South Platte
• Basin: South Platte
• Contract/PO #: C153954
• Grant Type: Non-Reimbursable
• Bill Number: SB01-157, HB02-1152, SB03-110, HB04-1221, SB05-084, HB06-1313, SB07-122
• Prepared By: Leonard Rice Engineering

proceeding.
SYSTEM OVERVIEW
The Left Hand Ditch Company represents the aggregate interests of all of the major ditches and
water rights in the Left Hand Creek basin, a southern tributary that flows into the St. Vrain Creek
below the Town of Longmont. Native water supplies in the Left Hand Creek basin in Water
Division 1, Water District 5 are limited. The ditch company's primary supply comes from a
headgate located on the South Fork St. Vrain Creek across from the headwaters of James Creek.
St. Vrain diversions are conveyed down James Creek into Left Hand Creek. A State Supreme
Court Ruling involving the ditch company (Coffin v. Left Hand) regarding the diversion of water
from St. Vrain Creek for use in Left Hand Creek established the legal precedent that defines the
prior appropriation system in the western United States.
Based on its senior water rights holdings, the ditch company can often dry up the South Fork St.
Vrain Creek at its diversion point and is essentially entitled to all of the available flow in Left
Hand Creek. Storage units used by the Left Hand Ditch Company include high-mountain
reservoirs (Left Hand Park Reservoir, Lake Isabelle, and Gold Lake) and lower-basin reservoirs
(Left Hand Valley Reservoir and Allens Lake). The ditch company also uses transbasin water
from the Colorado Big Thompson (C-BT) project. The Left Hand Water District is a shareholder
in the Left Hand Ditch Company and uses the ditch company infrastructure, along with its own
treatment plants and fore bay reservoirs to deliver potable water to rural landowners within the
area.
Key structures identified in the Left Hand Ditch System are as follows:
1) Left Hand Ditch
2) Left Hand Ditch Reservoir System
• Left Hand Valley Reservoir
• Allens Lake
• Left Hand Park Reservoir
• Lake Isabelle
• Gold Lake
These infrastructure components are owned by the Left Hand Ditch Company:
Left Hand Ditch Company
Post Office Box 229
Niwot, Colorado 80544
Contact: Richard Behrmann, President
Phone: [phone]
An overall graphic representation of the Left Hand Ditch system infrastructure and pertinent
stream gages is shown on Figure 1. A schematic diagram of the Left Hand Ditch system, storage
structures, and diversions is shown on Figure 2.
Left Hand Ditch Operating Memorandum.doc 2 of 17 January 5, 2005