Hydrohistorian
Lesson C4 · The Ledger · records & administration
Is the river getting harder to divert from?
“The river is getting harder to divert from” is the thing every ditch rider says and almost nobody has put a number on. The call record can: how many days a year is this district under any call at all? More days under call means more of the year when being junior means being dry.
Days under call — Clear Creek district, by year
Bar = share of the calendar year with at least one call in force that can lawfully reach this district (calls naming only other districts dropped; calls stating no district kept — unstated means unknown, and DWR only began stating districts around 2015, so early years lean on the kept-unknowns). “Tightest” is the most senior controlling priority that year reached. Saturated bars are themselves a finding: on a fully-appropriated Front Range creek, some call senior to almost everything can stand essentially year-round.
Reading it honestly
Two cautions before concluding a trend. Recording practice changed — recent decades are recorded more completely than the 1970s, so part of any rise is bookkeeping. And days-under-call measures administration, not water: a wet year with an aggressive senior can out-call a dry year with patient ones. This is the same discipline as lesson B4 — deliberately shown as per-year values rather than a single “tightening index,” because a composite would bury exactly the caveats that matter.
What this does not let you conclude
Days-under-call counts district-scoped calls in our snapshot; calls administered from other districts that reach in, and anything before the record’s start, are not in the bars — and administration intensity is evidence about scarcity, not a measure of streamflow. Advisory reading aid on public data — never an administrative or legal conclusion, and never a substitute for DWR administration or an engineer’s analysis. Our methodology has not yet had outside expert review: how this is built.