CAGRD and Tucson Finalize Water Credit Transfer
On September 5th, the Central Arizona Project Board of Directors approved a historic agreement between the Central Arizona Groundwater Replenishment District (CAGRD) and the City of Tucson on Colorado River water recharged in Pima County. Over a 20 to 25-year period, CAGRD will purchase a total of 100,000 acre-feet of long-term storage credits from Tucson, and can purchase up to 5,000 acre-feet per year. The CAGRD, established in 1993 by the state legislature, serves as a method for property developers and water providers to demonstrate a 100-year assured water supply under Arizona law. Tucson generated the credits by storing renewable water supplies, including CAP water and reclaimed water, at several recharge facilities near Tucson. Because the recharge facilities and stored water are located outside of the city’s water service area, Tucson determined that it is unable to efficiently recover and directly utilize them. Thus, both parties consider this agreement a win-win situation. The transaction provides CAGRD with water storage credits to meet its replenishment obligations in the Tucson region. Concurrently, the transaction allows the City to optimize its water portfolio by replacing water located outside of their service area with funding for development of local water resources and infrastructure.
Unique Underwater Method Used for Horse Mesa Dam Repair
In September 2013, engineers at the Salt River Project (SRP) successfully executed a unique underwater method to repair a damaged intake structure for Horse Mesa dam’s hydroelectric Unit 4. In June 2012, the collapse of a guide vane inside the penstock intake–that is, the huge pipe that passes through Horse Mesa dam from Apache Lake into the generating unit below on the Canyon Lake side–shutdown Unit 4 and the 119 megawatts of electricity generated by its pump-back unit. To repair the damage SRP might have had to drain Apache Lake, significantly affecting marina operations and boating enthusiasts at the reservoir. Instead, they worked with Seattle-based Global Diving & Salvage on an innovative underwater technique. Global Diving & Salvage hauled 29 tractor trailer loads of equipment to the site, including an enormous working barge system to support the construction efforts, as well as cranes, boats and other support features. The effort necessitated a 24-member crew working around the clock on the barge to support the divers working under water. Twenty crew members worked above water while two teams of two divers, trained not only as divers but also as construction personnel worked 10-hour shifts. The teams used a specialized technique called “saturation diving.” A diving bell brought a team to the work area 160 feet below the surface of Apache Lake from a pressured habitation vessel on the barge. One diver remained in the bell for 5 hours while the other worked on repairs and then they reversed roles. The second two-man crew took over the work for the next 10-hour shift. The teams remained under pressure for 30 days while work was completed. This arrangement allowed them to work underwater for long periods of time at a greatly reduced risk of decompression sickness.
Rio Verde Community Earns Audubon Award for Sustainable Communities
The Rio Verde–a private community east of Scottsdale–has earned the Green Community Award from Audubon International, a non-profit environmental education organization. Rio Verde is the first community in the Western United States and the second private community in the country to earn this award for its green initiatives. Rio Verde’s initiatives include native landscaping and fruit tree planting for public consumption, local food sourcing for on-site dining facilities, and a solar-powered community center. In addition, the Rio Verde Country Club utilizes reclaimed wastewater for irrigation, and landscaping crews use integrated pest management whenever possible. The Green Community award recognizes environmental achievements and is an intermediate milestone en route to earning the designation as a Certified Audubon Sustainable Community.
Reclamation Forecasts Low Lake Powell Water Release for 2014
As part of its ongoing management of Colorado River reservoirs, the Bureau of Reclamation determined that only 7.48 million acre-feet (maf) would be released from Lake Powell in water year 2014 (Oct. 1, 2013 – Sept. 30, 2014). An annual release of 7.48 maf is a 9 percent reduction from 2013 and the lowest release since the filling of Lake Powell in 1963. Lake Mead is projected to decline an additional eight feet during 2014 as a result of the lower Lake Powell annual release. However, Lake Mead will continue to operate under normal conditions, with water users in the Lower Colorado River Basin and Mexico receiving their full water allotments. These projections reflect Reclamation’s 24-Month Study Report, which provides projected reservoir operations for all major system reservoirs in the Colorado River Basin over a two-year period. Projections are updated monthly to reflect changes in weather and the resulting hydrology. Thus, they are subject to change as the year progresses, and the picture may improve if there is good winter snowpack. Annual releases are based on reservoir levels in Lake Powell and Lake Mead and the 2007 Colorado River Interim Guidelines for Lower Basin Shortages and the Coordinated Operations for Lake Powell and Lake Mead, which provides Colorado River users with a degree of certainty about annual water deliveries.