Boulder and Left Hand Ditch


Boulder & Left Hand Ditch

Established: December 1, 1873

Priority Number: 36

Acres under ditch: 4000 originally

Water Source: Boulder Creek

Boulder & Left Hand Ditch shares the headgate in downtown Central Park with Boulder & White Rock Ditch and North Boulder Farmers Ditch. The three flow together down the old channel of the Boulder Slough to 21st Street, where Boulder & White Rock divides off. The remaining two ditches wind through the Goss Grove neighborhood, pass the Dairy, dive under Circuit City and Target, and then re-emerge behind Earl’s Saw Shop. At Foothills Parkway and Pearl, the two ditches divide, but continue traveling together, side-by-side for several more miles, before they go their separate ways.

Boulder & Left Hand owns the Twin Lakes Reservoirs in Gunbarrel, and Hayden Lake near the Boulder airport. Boulder & White Rock Ditch carries Boulder & Left Hand water into Hayden Lake, where it is stored, and then released later in the season into Boulder & Left Hand Ditch. Boulder & Left Hand carries water to farms out as far as Longmont, to 287 and Plateau Rd, and to Hwy 52 and 79th.

Our complex interrelated water system makes it possible for Boulder & Left Hand users to access water from North Boulder Farmers Ditch and Six Mile Reservoir. They can also use C-BT water via the Boulder Supply Canal. Access to multiple water sources gives farms more certainty in our arid land.

Why do Boulder & Left Hand and North Boulder Farmers run parallel for so many miles? Why go to all the back-breaking labor of digging two separate ditches when one ditch could water the whole area?

According to Richard Behrmann, the answer has to do with limitations in water measuring technology in the 1870s. At that time, there was no accurate way to determine how much water a lateral headgate was taking. The sizes of headgates could be regulated, but that was just half of the equation. The flow going through a particular sized headgate would still vary widely. Farmers knew this intuitively, from their own experience. And so they knew that their upstream neighbors could be taking more than their share of water.

This is why the Boulder & Left Hand Ditch decided to dig their own separate ditch, just uphill from the more senior North Boulder Farmers Ditch, to guarantee that they could get ALL of their own water out to their users, way out east.


This piece of binder paper is the 1967 agreement between Boulder & Left Hand and Boulder & White Rock, to build the divider gate at 21st Street. The ditches had worked together well for a long time, their boards and shareholders overlapped, and business could be conducted with a handshake and without lawyers.  Scan courtesy of Boulder and Left Hand Ditch Company.

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