2013 Water Year Determination

April 15, 2013

It shouldn't be a surprise to anyone that it has been determined that the April 1 water-year forecast for the Trinity watershed is "Dry." The determination was made by the Calif Dept of Water Resource and National Weather Service.

The forecast is for 823TAF (thousand acre feet) of Trinity Basin inflow putting this year squarely in the middle of the Dry 650-1025TAF range.

Three flow alternatives were presented to the Trinity Management Council (TMC) for the "shape" of the 453TAF volume that is allowed to be release into the Trinity River between April and October. The shape of the flow does not change the total release volume.

After much deliberation, the TMC selected Alternative 3. The exact release days and times will be determined by the USBR Central Valley Project Operations team.

The river flows began on April 21 and included an 8-day, 2,000 cfs bench (April 23--May 1) on the ascending limb, followed by a 2-day peak release of 4,500 cfs on May 2-3 The descending limb includes three benches designed for monitoring purposes.

The 8-day bench hopes to improve juvenile rearing habitat in April and May. The low maximum of 4,500 cfs should help preserve the lake level for tourism this summer.

There are two other Trinity Lake releases this year to watch. First is the biennial "Hoopa Boat Dance" release around Labor Day weekend (what did they do before the dam??), and the second is a proposed "Supplemental Fall Release" (similar to 2012) that TLRA opposes due to lack of scientific-need data. Last year's "Supplemental Fall Release" had no measurable effect.

If you would like to read all of the science data and discussion about this water year and flow alternatives, download the draft Workgroup Flow report (3.3MB) from April 10, 2013.