Frequently Asked Questions
1.
What is the 2006 water year type in the Trinity basin and how much water will be released into the Trinity River?
Both the February and March preliminary forecasts for the Trinity basin have been for a "wet" water year. The official water year classification will be issued by the Bureau of Reclamation on April 8. In a wet water year, a total volume of 701,000 acre-feet would be released into the Trinity River . Refer to Current Flow Schedules and Releases for more information on each water year type.
2.
How was the spring flow release schedule determined?
Based on the preliminary water year forecasts in February and March, program staff and technical representatives of the Trinity River Restoration Program partners are developing flow release recommendations to meet various restoration objectives for the Trinity River. These flow recommendations will be presented to the Trinity Adaptive Management Working Group and the Trinity Management Council (TMC) in late March for consideration. The TMC will then recommended a flow release schedule to the Bureau of Reclamation, which will make a final decision by mid-April.
3.
How high will the peak flows be this year, and how long will they last?
If the preliminary forecasts hold for a wet water year, the approved schedule is likely to include a 5-day peak release of 8,500 cfs on or about May 17 to 21. Since this will be the first time fishery restoration flows of this magnitude have been released, program staff will closely monitor properties adjacent to the river during the ramp up to higher flows. Initial ramping from the winter base flow of 300 cfs will begin on or about April 22.
4. How can I stay informed about current and planned flow releases?
The Bureau of Reclamation has posted the annual flow schedule on the internet [PDF - off site]. Additionally, the Trinity River Restoration Program maintains an email list to keep the public informed about planned flow release changes. If you are interested in being added to the email list, please contact Andreas Krause by phone (530-623-1800) or email akrause@mp.usbr.gov. Otherwise, please feel free to call or stop by the Trinity River Restoration Program office.
5. What method do you use to forecast the water year type?
The Bureau of Reclamation determines the water year type on April 1 by comparing the calculated inflow to Trinity Reservoir to the table below. The inflow to Trinity Reservoir is calculated by summing the actual amount of runoff that has occurred from October 1 until April 1 and an estimated volume of water that Reclamation forecasters predict will runoff during the months remaining in the water year (i.e. April 1 through September 30).
Water Year Classification:
| Water Year Type | Inflow to Trinity Reservoir (Acre-Feet) |
| Extremely Wet | >2,000,000 |
| Wet | 1,350,000 to 2,000,000 |
| Normal | 1,025,000 to 1,350,000 |
| Dry | 650,000 to 1,025,000 |
| Critically Dry | < 650,000 |
6.
Will late summer/fall fishery protection flows be released this year?
During 2005 fish biologists and other scientists from the Trinity River Restoration Program staff and partners reviewed monitoring data collected during and after the fall flows released in August and September of 2003 and 2004. They are continuing to evaluate biological implications of fall releases on population genetics and possible mixing of the spring and fall runs of Chinook salmon. Last year the Trinity Management Council recommended against reserving any water volumes from the flow schedule for possible use in the fall, and ultimately no fall flows from any source were released. While fish health monitoring will continue this year, no fall flows are anticipated at this time.
7. How do Central Valley Project (CVP) operations impact withdrawals from Trinity Lake?
The amounts and timing of Trinity basin exports are determined by subtracting Trinity River scheduled flows and targeted carryover storage from the forecasted Trinity water supply. Trinity River Division operations are integrated with the Shasta Division and other CVP water supply reservoirs. Exports are made after considering many different operational factors including: water year type, minimum flow and water temperature requirements for the Trinity and Sacramento Rivers, storage levels and refill potentials in both reservoirs, as well as demand for water supply and hydroelectric power generation.
8. How much lower will Trinity Lake be compared to recent years?
Potential changes to reservoir storage levels resulting from implementation of the Record of Decision (ROD) were modeled using the computer program CALSIM in the original Trinity River Restoration Program EIS/EIR, and updated for the draft SEIS/EIR and the Central Valley Project Operations Criteria and Plan (OCAP). As a result of implementing the ROD, it is projected that average end-of-water-year carryover storage would decrease by about 116,000 acre-feet (-8%). This equates to an average end of year lake elevation of 2286 ft. under current conditions compared to 2296 ft. prior to implementation of the ROD. This will vary depending on water year type and other factors described above. Refer to the attached diagram for more information.
9. What time of the season is the greatest draw down likely to occur?
The largest volume of water released to the Trinity River for fishery restoration purposes takes place from early May to mid-June. Water exports to the Sacramento Basin are more likely to occur later in the summer as Reclamation's Central Valley Operations office balances competing needs for irrigation, power generation, and Sacramento River temperature control.
10. What will happen to existing private structures that are impacted by the higher dam releases?
Work is proceeding as quickly as possible to identify and address structures at risk. Modifications to four river crossings (Browns Mountain, Salt Flat, Poker Bar and Biggers Road) have been completed and are open to traffic. One house has been acquired and will be removed. Other potentially impacted structures are being located on aerial photographs and owners are being contacted to determine structure type and to identify any issues not evident from the photographs. It is our goal to contact all property owners along the river from Lewiston Dam to the confluence of the North Fork Trinity River to discuss their individual situations prior to implementing the higher releases.
11. How big is this next storm going to be?
A: The National Weather Service provides rainfall and river flow storm predictions for the Trinity River at Burnt Ranch and the Trinity River at Hoopa. The predictions are updated twice daily.
- Trinity River at Burnt Ranch
- Trinity River at Hoopa
12. What is the current streamflow?
Real-time streamflow information for all rivers in California (including the Trinity River) can be obtained from one of the following two websites:
13. What are the current conditions (inflow, outflow, storage) at Trinity Lake?
This information can be obtained from the CDEC website.
14. What are the current and scheduled flow releases from Lewiston Dam into the Trinity River?
Real-time flow releases are measured by the U.S. Geological Survey. The annual release schedule developed by the Trinity River Restoration Program to benefit Salmonid recovery is posted here. Other scheduled releases, such as for Safety of Dams, are posted at: cdec.water.ca.gov/cgi-progs/queryRES?lew, then click on the "Get last month of data" button. Please note that Safety of Dams releases are scheduled in response to storm events and typically have no more advance warning than several days.
Scheduled release changes at Lewiston for the Trinity River can also be obtained by calling the "River Release Recording" phone number. The phone message is updated daily, but only with the current release and any "scheduled" changes. "Scheduled" changes are those officially transmitted by Central Valley Operations, and therefore, occur usually only a couple of days to several hours before changes are made, depending on the circumstances. The recording lists the Keswick release for the Sacramento River first, so those interested in Trinity River releases need to wait for the Trinity portion of the recording. The phone number is 530-246-7594.
15. How does the Bureau of Reclamation decide to make higher flow releases to the Trinity River during the winter?
During the winter, the Bureau of Reclamation maintains lower levels in Trinity Reservoir to provide a buffer in the event of an extremely large winter storm. The quantity of that buffer is based on several factors, and primarily references many years of hydrologic record for the basin. Maintaining storage space is a very important aspect of flood control operations, and is fundamental in protecting areas downstream of Trinity Dam, as well as the dam itself. As winter storms fill Trinity Reservoir, the Bureau of Reclamation may need to increase releases to the Trinity River to maintain the lower lake levels. Because these elevated winter releases help protect the dam, they are commonly called "Safety of Dams releases" and may or may not occur in conjunction with actual winter storms. Safety of Dams releases are typically no greater than 6,000 cfs, but may go higher if conditions warrant.
16. WINTER STORMS caused trees and other woody debris to fall into the river near my house. does the Trinity River Restoration Program plan to remove the debris from the river?
The Trinity River Restoration Program has no authority, and is not responsible, for removing woody debris from the river. Private landowners and public land management agencies make decisions about removing debris that might impair public safety, threaten the integrity of bridges or other structures, or increase the likelihood of local flooding. If landowners elect to remove debris, we urge that landowners are cautious and follow safe work practices.
If left within the watercourse, fallen trees and bushes do play an important role in the juvenile life stages of fish in the river. Large woody debris provides cover, shade, and structure for fish. It also causes local scour that refreshes gravel, and increases the number and size of pools or holes for fish to utilize during low flow periods. Large woody debris contributes to the geomorphic processes, resulting in the creation and maintenance of the complex river habitats required by Chinook and Coho salmon and steelhead.