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water quantity

Making it rain: Scientists hope to boost precipitation in Tahoe

By inserting chemical compositions into clouds, Scientists with the Reno-based Desert Research Institute are planning to stimulate precipitation in Lake Tahoe during the winter in the hopes of increasing the snow pack. A heavier snow pack will supply more water during spring run-off and prevent the Truckee River Watershed from drying up in the autumn.

The scientific technique — called cloud seeding — is becoming more prevalent as it can spur a 5-10 percent increase in annual precipitation at a targeted area, according to DRI research scientist Arlen Huggins.

“Cloud seeding can be extremely beneficial, especially in the drought-stricken west,” Huggins said during a a recent presentation at the University of California, Davis, Tahoe Environmental Research Center at Sierra Nevada College.

Lake Tahoe area cloud seeding short of cash

With winter approaching and governments struggling through fiscal difficulty, researchers are in search of money needed to squeeze a little extra moisture from snowstorms. The Desert Research Institute in September secured a promise of up to $100,000 from the Western Regional Water Commission to fund a cloud-seeding program for the Lake Tahoe area. In late October, the DRI plans to seek a larger contribution from the Truckee River Fund, which is administered by the Truckee Meadows Water Authority.

It's part of an effort to continue a 25-year-old program nearly killed when the 2009 Legislature pulled state funding that was going to the DRI. A last-minute pitch to water purveyors saved the program last winter, and now officials are trying to line up the money needed during the winter of 2010-11.

Lake level low

Daily Tribune: In the works for the weekend
Staff report

When the water in Lake Tahoe falls below the natural rim, at 6,223 feet, water stops flowing into the Truckee River. At midweek, Lake Tahoe measured 6,223.25. If the lake level drops below the natural rim, Tahoe turns into an enormous bathtub.

Lake level nears natural rim

Annie Flanzraich / North Lake Tahoe Bonanza
Dec. 4, 08

With Lake Tahoe’s water level nearing the natural rim, water authorities are hoping for record-breaking precipitation to bring the level up.

“We desperately need a big winter and a big snowpack to bring Lake Tahoe back up again,” said Federal Water Master Garry Stone.

When the water in Lake Tahoe nears the natural rim, at 6,223 feet, water flows more slowly into the Truckee River. At midweek the lake measured 6,223.25. Under normal conditions, the flow into the Truckee is about 250 cubic feet per second. The current rate is about 12 cubic feet per second, Stone said. If the lake level drops below the natural rim no more water will flow into the Truckee.

“We can’t get any more water out of it,” Stone said. “It’s like a bathtub, we do not have the ability to release water through the natural rim.”

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Dreaming of a wet winter at Lake Tahoe

By Annie Flanzraich
Bonanza News Editor

With Lake Tahoe’s water level nearing the natural rim, water authorities are hoping for record-breaking precipitation to bring the water level up.

“We really desperately need a big winter and a big snowpack to bring Lake Tahoe back up again,” said Federal Water Master Garry Stone.

When the water in Lake Tahoe nears the natural rim, which is 6223 feet, water flows less quickly into the Truckee River. As of Wednesday night the lake measured at 6223.25. Normally there are about 250 cubic feet per second running into the Truckee. Right now the rate is about 12 cubic feet per second, Stone said. If the lake level drops below the natural rim no more water will flow into the Truckee.

“We can’t get any more water out of it,” Stone said. “It’s like a bathtub, we do not have the ability to release water through the natural rim.”

After that water from Boca Reservoir and smaller natural streams will flow through the Truckee. Stone said there is enough water in Boca to supply the river until sometime in December.

While the level of the lake does not affect water supply at the towns and villages in the Basin, it does affect other areas like Reno, Stone said.

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Landmark agreement settles long-standing river dispute

Associated Press Writer and published online by Lahontan Valley News
September 6, 2008

RENO, Nev. (AP) - With the scenic stream flowing behind them, officials from Nevada, California and the federal government signed a landmark agreement that settles a century-plus-old dispute over the Truckee River's water.

Sen. Harry Reid, D-Nev., and Interior Secretary Dirk Kempthorne joined local and state officials at the signing ceremony Saturday for the Truckee River Operating Agreement. The complex document allocates the river's waters between the two states, and balances the interests of urban users, downstream farmers and the Pyramid Lake Paiute Tribe.

"I'm so happy that President Bush signed off on it," Reid told a crowd of about 400 at a downtown Reno park. "It's an example of what teamwork and bipartisanship can accomplish."

The Truckee flows more than 100 miles from the California side of Lake Tahoe to its terminus at Pyramid Lake on Nevada's high desert, about 30 miles northeast of Reno.

Under the agreement, California will get two-thirds of Lake Tahoe's water to Nevada's one-third, while Nevada will receive 90 percent of the Truckee's water to California's 10 percent. It also calls for Nevada to get 80 percent of the Carson River's water to California's 20 percent.

The two states approved an interstate compact on the Truckee's waters in the early 1970s, but it was never ratified by Congress. Kempthorne hailed the new agreement, saying it was similar to ones reached in recent years over the Colorado and Snake rivers. He stressed that no one surrendered any water rights under the latest deal.

"This day is part of a new day in the West - a day when step by step, agreement by agreement we resolve all the bitter water disputes in the new spirit of cooperation and partnership," he said.

The deal stemmed from Reid-sponsored legislation passed by Congress in 1990 that directed both states, the U.S., the tribe and the Reno area's water purveyor to settle their differences over the river.

Lawsuits over the Truckee spanning back to the 1800s gave it a reputation for being one of the West's most litigated rivers. Under the settlement, the amount of drought water storage for the Reno area will triple, and Reno, Sparks and Washoe County will provide water rights to improve water quality in the lower Truckee. The river system is the Reno area's only water source.

Officials said the agreement will improve conditions for the threatened Lahontan cutthroat trout and endangered cui-ui fish, as well as for Nevada wetlands. It also will enhance recreational opportunities in both states.

A final environmental study by the U.S. Department of the Interior and California Department of Water Resources found no significant adverse impacts from the agreement. The document concluded the settlement would provide a major boost to the river's water quality and fishery.

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Replicating Natural Runoff Through Retention and Dissipation

A simulation model for estimating retention volumes
By Randel Lemoine, Stormwater E-magazine September 2008

Natural watersheds retain and dissipate most rainwater. This water is retained on the surfaces of vegetation and in ground depressions, such as puddles, wetlands, and marshes. Natural processes such as transpiration by plants, infiltration into the soil, and evaporation dissipate this water. A natural watershed’s retention and dissipation capacity is sufficient to prevent any runoff from occurring during most rainfalls. Occasionally, when there is a heavy rainfall, a small amount of the rainwater becomes surface runoff that enters nearby creeks, rivers, and lakes.
The natural processes that retain and dissipate the rainwater are diminished when land is developed, whether for agriculture or for urban use. Land development removes vegetative cover, fills in low areas, compacts the soil, and creates impervious areas. The result is increased water runoff flowing more frequently across the land and discharging into the watershed’s rivers, streams, and lakes. This increased runoff causes downstream flooding, accelerated soil loss from erosion, unstable stream banks, and pollution of water resources.

Problems in Mitigating Increased Runoff
Detention basins temporarily hold collected runoff and slowly release the water. They are constructed in an attempt to mitigate the downstream flooding problems by limiting the peak discharge rate of the runoff. However, they do not reduce the volume of runoff discharged into the nearby creeks, rivers, and lakes. Consequently, the runoff volume discharged remains greater than when the land was in its natural condition. Therefore, detention basins fail to match the natural runoff pattern that occurred prior to the land being developed. Streambank erosion, stream channel instability, and occasionally even downstream flooding continue to be problems.
Retention basins hold a certain volume of water. There are two types of retention basins: water-quality basins and water-volume basins. Water-quality retention basins remove pollutants collected by the runoff. These basins allow the runoff to pass through after holding it long enough to give natural processes time to remove a percentage of the pollutants. They do not reduce the volume of runoff discharged. Water-volume basins capture and dissipate the runoff, thereby reducing the volume and frequency of discharges from a site. A discharge of runoff occurs only when the runoff volume exceeds the basin’s maximum retention volume. However, the actual volume available for retaining the runoff from the next rainfall depends upon the dissipation of the water held from the previous rainfall. Therefore, a key factor in determining the effectiveness of a water-volume basin is the dissipation rate.
Two commonly used methods for estimating the maximum retention volume for a water-volume retention basin are the “90% Rule” and the “Two-Year-Difference Rule.” The 90% Rule requires the capture of 90% of the runoff coming from a developed site. The Two-Year-Difference Rule requires that the maximum retention volume should be equal to the difference between the two-year runoff from the developed site and the two-year runoff from the site in a natural undeveloped condition. Neither rule addresses the necessary dissipation rate relative to the storage volume. Therefore, it is uncertain that the maximum retention volume derived by these rules will adequately address the adverse effects caused by the increased runoff coming from developed land.

An Alternative Method for Determining Retention Volume and Dissipation
An alternative to these methods is to use a simulation model. This model is set up on a Microsoft Excel spreadsheet and uses local historical precipitation data. The runoff volume for each day of the simulation is estimated using the TR-55 runoff equations (USDA 1986). The retained water volume for each day is calculated by taking the difference between the precipitation volume and the runoff volume, then subtracting the daily dissipation volume. This retained water volume is added to the precipitation of the next day, which is valid because the effect of the retained water on the next day’s runoff volume has the same effect as if it were part of the precipitation for the next day. Adding the previous day’s retained water to the precipitation provides the continuity needed for determining the appropriate combination of retention and dissipation to replicate the natural runoff.

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Real-Time Information: USGS stream flow and well water gages through Truckee River system

From the KRNV website: describing our watershed. Click on website for gaging sites & real-time data.
Truckee Meadows is a bowl-shaped valley, approximately 10 miles wide and 16 miles long, containing the cities of Reno and Sparks with a combined urban population of approximately 280,000 persons. The Truckee Meadows also includes Pleasant Valley and Washoe Valley to the south, the latter valley containing Washoe Lake and Little Washoe Lake. Both these valleys are drained by Steamboat Creek, which then runs along the eastern portion of the Truckee Meadows and empties into the Truckee River near Vista and the beginning of the lower Truckee River canyon. Along the way, Steamboat Creek picks up the return flows of numerous irrigation ditches to the south of the Truckee River, the most important being Steamboat Ditch, Last Chance Ditch, and Lake Ditch, as well as the Boynton Slough. The Boynton Slough is the recipient of some of these other ditches' return-flow waters as well. Steamboat Creek also receives the treated effluent from the Truckee Meadows Water Reclamation Facility (formerly the Reno-Sparks joint sewage treatment plant).
The eastern part of the Truckee Meadows was a vast marshy wetland prior to development of the area, and remnants of low-lying areas are still farmed today. Loss of this wetland area has exacerbated flooding in the Sparks industrial area.The Truckee Meadows urban area is the largest user of municipal and industrial water from the Truckee River. While municipal and industrial water use (withdrawals) in the Truckee Meadows total approximately 65,000 acre-feet per year, nearly three times this amount (172,383 acre-feet per year, 1973-1994) is diverted out of the lower Truckee River Basin at Derby Dam and into the Truckee Canal for agricultural use in the Newlands Project in the lower Carson River Basin.

Treatment plan would put water from sewers back in regional supply

Posted: 2/13/2008

Using reclaimed sewer water to irrigate residential lawns and injecting it into the ground for reuse as drinking water are ways to stretch water imported to the North Valleys areas of Washoe County, according to a new Reno plan.

"Reclaimed water in parks and golf courses is one thing," said Sarah Chvilicek, who lives in Silver Knolls. "But in people's yards with children and pets is a different thing. Why are we trying to make all these oases in a desert?"

The reclaimed water proposal -- part of a larger infrastructure plan that will be reviewed tonight by the Regional Planning Commission -- comes as Washoe County faces potential water shortages down the road.

The water facilities plan identifies 30,743 acre-feet of potential water resources to meet an expected demand of 59,042 acre-feet by 2030 for an area covering central Reno and Sparks, the south Truckee Meadows, Sun Valley and Spanish Springs. An acre-foot of water covers an acre of ground with a foot of water or 325,851 gallons, the amount used by a family of four in a year.

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