WSP09401

• File Number: 8056
• Description: Drought Preparedness
• State: CO
• Basin: Statewide
• Date: 8/28/1986
• Author: CDM
• Title: Phase I - Drought Study - City of Loveland Raw Water Supply System
• Water Supply Pro - Doc Type: Report/Study

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2.0 METHODOLOGY

2.1 YATER AVAILABILITY

The City's raw water sources include the following:

1. Big Thompson River direct-flow water rights.
2. Ovnership in a number of private irrigation ditch and reservoir
companies.
3. Ownership of Colorado-Big Thompson Project (CBT) units.
4. Ownership of Yindy Gap Project (YGP) units.

Both the CBT and Yindy Gap projects derive their supply from streams in the

Upper Colorado River Basin. Conveyance facilities (e.g., Adams Tunnel,

Dille Tunnel, Charles Hansen Feeder Canal, etc.) are operated and

maintained by the Northern Colorado Yater Conservancy District (NCYCD) and

MS-NCYCD to transport CBT and WGP water across the Continental Divide and

deliver that water to shareholders along the Front Range and in

northeastern Colorado. Figure 2-1 illustrates the various components and

raw water sources of the City's water supply.

The first step in pursuing the study objectives was to determine the

physical supply of water that would be available in any given month in the

Big Thompson River and from the CBT and Windy Gap projects. Since

streamflow is highly dependent upon such natural factors as rainfall, and

snowfall and snowmelt, this determination is based upon probabilities and

expected extremes rather than constant values for any given month or period

of months. Techniques used to define streamflow characteristics during

low-flow periods are referred to as "drought analyses."

A drought is defined as "some period of time with below-average streamflow"

and the severity of any given drought is commonly expressed in terms of:

2-1