On December 5, 2003 for all of Biff Warren's efforts, hard work and dedication to and for the youth in Niwot Youth Sports, the Nimbus field site name was changed to the Biff Warren Baseball Complex. The site was originally acquired in 1992 as a result of the efforts of NYS Baseball President Dan Knollenberg, Baseball Director Biff Warren, and Softball Director Jim Martinsen in cooperation with Left Hand Water District President Leroy Schlagel and Manager Jim Dickey. Construction of the field began in 1993 with a group of volunteers, including Greg Hagen.

Located near the Left Hand Water District Offices on Nimbus Road at the intersection with Left Hand Creek, the site is owned by Left Hand Water District which leases it to Niwot Youth Sports at nominal cost. The District also allows use of its holding pond for the ditch water used to irrigate the fields. The site was offered to Niwot Youth Sports to replace the old Johnson Fields site in Niwot.

Greg Hagen Field

Greg Hagen Field was dedicated August 11, 1996, as a memorial to Greg Hagen who died tragically in an auto accident in 1993 at the age of 39. Greg's wife Nancy, his son Andrew and his daughter Chelsea established a memorial fund in Greg's memory through Niwot Youth Sports. Hagen Field is the largest NYS field, with fences of almost 300 feet. Dugouts were completed in 1996 by Eagle Scout Sam O'Donnell, and grass and irrigation were added in the fall of 1997 with the assistance of the Colorado Rockies and a group of dedicated volunteers, including Tim and Sheryl Shuminsky, Gregg and Joe Hangge, and Biff and Susan Warren. Other contributions were received from Jay Anderson (sign), Rock Creek Landscape (irrigation system), and BMC West (lumber). Greg Hagen's parents have established a $10,000 endowment fund through NYS to provide funds for maintenance of the field. The field is used primarily by NYS Seniors baseball players ages 13-15.

Kevin Ritz Field

Kevin Ritz Field was dedicated September 25, 1997, in recognition of donations of over $41,000.00 to Niwot Youth Sports by the Colorado Rockies and Kevin Ritz through the Robert R. McCormick Tribute Foundation’s Youth Field Program. Ritz Field is a miniature of Coors Field with similar outfield fence configuration, a warning track and grass infield. The field was named in honor of the pitcher Kevin Ritz, who holds the Rockies’ record for victories in a season with 17. Niwot Youth Sports Executive Director Tim Shuminsky, along with Baseball President Bill Lambert, President-Elect Joe and Lori DeMerssman, Baseball Director Phil Garcia, and Fields Coordinators Gregg Hangge and Rick Kurcab were instrumental in obtaining the Rockies grant and organizing and supervising the effort. Other donations of concrete and dugout lumber were received from Tracy Nissen of Total Concrete and Wickes Lumber. The field is used primarily by Niwot Youth Sports baseball players ages 9 to 12.

Columbine Field

Columbine Field was dedicated to the lives of the students and teacher who died at Columbine High School in Littleton will be installed. The field was initially constructed by Niwot Youth Sports volunteers in 1993 who built a backstop and dugouts. The field was graded and a temporary outfield fence was installed. In 1999, the Port Arthur Foundation, established by a Niwot area family who wishes to remain anonymous, offered to donate funds to allow completion of the field. An irrigation system, sod, and new infield dirt were added in early 1999 making the field playable by May. Gregg Hangge and Joe Hangge installed the new outfield fence with the help of other area youth. The field is large enough for use by 12 year olds as well as younger players. Kathy Peterson, Dick Smith, and Todd Petry of Left Hand Water District were instrumental in arranging for use of water for the new sod.

Bob Spencer Equipment Building

The storage and equipment building at Nimbus Fields was donated by Bob Spencer and R.A. Spencer Construction in 1998. Mr. Spencer coordinated construction of the building and obtained donations from various subcontractors. Tracy Nissen of Total Concrete, Inc., donated the concrete foundation. Gregg Hangge of Niwot Youth Sports designed the building and painted it. The building has allowed Niwot Youth Sports to maintain Hagen, Ritz, and Columbine Fields at minimal cost.