(Recasts, updates yields, adds reverse repo operation, analyst comments) By Karen Pierog CHICAGO, June 30 (Reuters) - Yields on longer-dated U.S. Treasuries fell on Wednesday to their lowest levels in more than a week as the market wound down 2021"s second quarter, while the amount of cash flooding into the Federal Reserve"s reverse repurchase operation set a new record high as it neared $1 trillion. The benchmark 10-year yield, which tumbled to its lowest level since June 21 at 1.438%, was last down 3.2 basis points at 1.4477%. The yield on 30-year bonds, which hit a session low of 2.047%, was last at 2.0701%. "I think a lot of it has to do with quarter end (portfolio rebalancing), probably some duration needs associated with the flip in the calendar (to July), and then a little bit of caution on Friday"s jobs numbers," said Ben Jeffery, U.S. rates strategist at BMO Capital Markets. The closely watched U.S. Labor Department"s report is expected to show that private payrolls along with government hiring increased by 700,000 in June, after rising by 559,000 in May, according to a Reuters poll of economists. The unemployment rate is forecast to have fallen to 5.7%, from 5.8% in May. Ahead of the government"s report, the ADP National Employment Report on Wednesday showed private payrolls increased by 692,000 jobs last month, topping the 600,000 rise forecast by economists polled by Reuters. Data for May was revised lower to show 886,000 jobs were added instead of the initially reported 978,000. Eased inflation fears kept yields from climbing despite the strong jobs data, according to Kathy Jones, chief fixed income strategist at the Schwab Center for Financial Research in New York. "You would think a 700,000 nonfarm payroll number would be cause for people to start sending yields up because real yields are so low and even nominal yields relative to the growth rate in the economy that we"re looking for are very low," she said. Federal Reserve Bank of Dallas President Robert Kaplan said on Wednesday that while there might not be "explosive headline numbers" in jobs reports, the labor force continues to improve. He also called for tapering of the Fed"s $120 billion in monthly asset purchases to start sooner than yearend. Meanwhile, volume in the Fed"s overnight reverse repurchase operation hit a record high for a second-straight day at $992 billion, up from $841.2 billion on Tuesday. "I would expect some of what"s happened today is quarter end- and month end-related, so we might see a temporary decline," said John Canavan, lead analyst at Oxford Economics. "But the trend is still towards higher demand, and I still think we"re likely to exceed $1 trillion at some point in the not-too-distant future." While volume has been building since March, it grew further after the Fed earlier this month raised the rate it pays on reverse repurchase agreements to 0.05% from 0% as part of technical adjustments to keep the effective federal funds rate from falling too low. The two-year Treasury yield was last less than a basis point lower at 0.2486%. A closely watched part of the yield curve that measures the gap between yields on two- and 10-year Treasury notes was last 2.5 basis points flatter at 119.57 basis points. June 30 Wednesday 3:11PM New York / 1911 GMT Price Current Net Yield % Change (bps) Three-month bills 0.045 0.0456 -0.005 Six-month bills 0.055 0.0558 0.000 Two-year note 99-193/256 0.2486 -0.003 Three-year note 99-102/256 0.4551 -0.008 Five-year note 100 0.875 -0.016 Seven-year note 100-56/256 1.2173 -0.027 10-year note 101-160/256 1.4477 -0.032 20-year bond 104-20/256 2.0002 -0.030 30-year bond 106-196/256 2.0701 -0.027 DOLLAR SWAP SPREADS Last (bps) Net Change (bps) U.S. 2-year dollar swap 7.75 0.00 spread U.S. 3-year dollar swap 10.75 0.00 spread U.S. 5-year dollar swap 7.00 0.00 spread U.S. 10-year dollar swap -2.75 0.00 spread U.S. 30-year dollar swap -31.50 -0.25 spread (Reporting by Karen Pierog; Editing by Nick Zieminski and Jonathan Oatis) Our Standards: The Thomson Reuters Trust Principles.