C-BT Project Quota

What is the Colorado-Big Thompson Project quota and how is it determined?

April Quota
Each April since 1957 the Northern Water Board has set a C-BT water delivery quota. The quota quantifies the amount of C-BT water the board makes available to allottees within Northern Water boundaries.

Because the C-BT Project was built primarily to deliver supplemental irrigation water to agriculture, April is an ideal month each spring to determine how much supplemental water is needed for the traditional (April – October) irrigation season.
November (Initial) Quota
Starting in the 1960s, C-BT Project water began moving from agriculture to municipal and industrial uses to help supply population growth. Correspondingly the demand for winter C-BT Project water deliveries also increased. Construction of the Southern Water Supply Project pipeline during the 1990s reinforced this trend.

Due to the growing need for year-round water deliveries, the Board in 2001 began declaring an initial quota effective November 1 each year. This enabled staff to establish winter water delivery accounts and transfer water between users prior to the traditional April quota.

The November quota is particularly useful for entities that deliver water during the non-irrigating season. While the Board currently sets quotas in April and November, directors may increase the quota at any time during the year.

C-BT Quotas, 1957-2016

310,000 Acre-Feet
Quotas are expressed as a percentage of 310,000 acre-feet, the amount of water the C-BT Project was designed to deliver each year. A C-BT Project unit is equal to 1/310,000 of the total quantity of water the Board makes available in any particular year.

The Board typically sets a 50 or 60 percent November quota. Prior to 2001 (when the Board first established an initial November quota), the April quota traditionally ranged from 50 to 100 percent. Since 2001, the April quota supplements the Board's initial quota established the prior November.

A 100 percent quota makes 310,000 acre-feet of water available for delivery. In this scenario each C-BT allottee receives 1 acre-foot of water for each unit owned.

Under a 70 percent quota declaration (217,000 acre-feet available) each allottee receives 7/10 of an acre-foot per unit. Thus, an allottee who owns 100 C-BT Project units can receive 70 acre-feet of water under a 70 percent quota. Under a 50 percent quota declaration (155,000 acre-feet available) the same allottee with 100 C-BT Project units has the right to use 50 acre-feet.

Recent C-BT Quota News Releases

C-BT Supplemental Water
The C-BT Project's Colorado River water supplements Northeastern Colorado's native supplies. Supplemental water is defined as the quantity added to an already existing (and often deficient) water supply.

Water Savings Account
In addition to delivering supplemental water, the C-BT Project acts as a water savings account. It generally provides more water in dry years when Northeastern Colorado’s native supplies are low, and less water in wet years when local supplies and storage reserves are more plentiful.

Quota Decision Factors
The Board considers several factors before declaring a quota:
  • The amount of water stored in C-BT Project reservoirs
  • The amount of water stored in non-C-BT reservoirs in the Boulder Creek, St. Vrain River, Big Thompson River, Little Thompson River, Cache la Poudre River, and Lower South Platte River basins  
  • The water content of snowpack in East and West slope watersheds
  • The projected spring runoff and streamflows in East and West slope watersheds
  • Soil moisture conditions
  • Estimated water needs for future years
Additional Factors
Besides reservoir levels and snowpack, the Board takes into account the C-BT Project’s physical capability to transport and deliver water. At full capacity the C-BT Project can transport approximately 30,000 acre-feet of water each month to the East Slope.

The U.S. Bureau of Reclamation requires the C-BT Project transport a minimum amount of water for power generation. Reclamation and Northern Water meet annually to discuss power requirements and the minimum volume of water the C-BT Project will transport that year.

The Board also listens to input from water users and their supplemental water needs. 
With data from numerous sources, the Board determines how much supplemental C-BT water is needed to provide Northeastern Colorado with an adequate water supply while also considering the region’s future water needs.