What is a water call?

The short version

When a stream does not carry enough water to satisfy a senior water right, the owner of that right can ask the Division Engineer's office to administer the river. Water commissioners then order upstream rights that are junior to it — newer in priority — to reduce or stop their diversions until the senior right is satisfied. That request, and the administrative status it creates, is the call. DWR describes the call as the most junior water right that can divert, given the supply and demand at the time.

Who places a call and who enforces it

• The calling right is usually a ditch, reservoir or city intake that is not receiving its decreed amount.
• Water commissioners — DWR field staff assigned to each water district — check headgates, measure diversions and order curtailment.
• Division Engineers run the administration in each of Colorado's seven water divisions, under the State Engineer.
• Compacts can also drive administration. On the Rio Grande, for example, DWR curtails diversions to meet Colorado's delivery obligation under the Rio Grande Compact.

What “curtailed” means

If your right is junior to the call and located where curtailing it would help the calling right, you must stop diverting, or divert only what you replace under an approved augmentation plan or exchange. A right senior to the call can keep diverting its decreed amount. The call sits at a priority, not at a map location: the administration number of the calling right is the line. Rights with a smaller (older) number are in priority; rights with a larger (newer) number on the affected stretch are out of priority.

Calls are placed on a particular stream reach. A call on a tributary creek affects rights upstream on that creek; it does not automatically shut off rights on a different creek. A call on a main stem can reach far up its tributaries.

Futile calls

Curtailing a junior is pointless if the water would not reach the senior in time to be used — for example, if the stream between them would lose it to a dry channel. The Division Engineer can find a call futile for such rights and let them keep diverting. CDSS records these with the call type “FUTILE CALL.”

How often calls change

Calls follow the water. In spring runoff many basins are “free river,” with no call at all, because the stream carries more than every right needs. As runoff falls and irrigation demand peaks, calls are placed, move to older and older priorities, and are released when storms or reservoir releases add water. In a dry summer some calls stay on for months; others last a few days. DWR posts each call with the date and time it was set and released.

Reading the call list

The active-call list in CDSS gives, for each call:

• Calling structure — the ditch or reservoir whose right is short, with its WDID (see What is a WDID?).
• Water source — the stream on which the call is placed.
• Priority date / administration number — the line between in-priority and out-of-priority rights.
• Date set — when the call began.
• Call type — an ordinary call or a futile call.

The most senior active call in a division is the one with the oldest priority date. It tells you how far down the priority list the shortage has reached somewhere in the division — not that every stream is that short.

How BasinMind uses calls

BasinMind pulls the active calls for each division from DWR's CDSS service about three times a day and shows them on Today, on the Map and in answers from Ask BasinMind. The live box above is that list for the Arkansas basin (Division 2). If you need to know whether your ditch is curtailed, read Is my ditch in priority? — and confirm with your water commissioner. BasinMind is advisory only; the Division Engineer's office is the authority.