Rivermatics

USGS Streamgage 06730500

Boulder Creek at Mouth near Longmont, CO

Boulder Creek at Mouth near Longmont, CO is USGS streamgage 06730500 in Colorado, monitoring river discharge in hydrologic subbasin 10190005. It sits on the Boulder Creek, alongside 1 other gauge Rivermatics tracks on the same river. It drains a watershed of about 447 square miles. Discharge records at this site go back to 1927. Typical flow runs near 11.1 cfs in July and 58.4 cfs in April, with the higher of the two arriving in April. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.

View live conditions & forecast →

Gauge details

State
Colorado
Drainage area
447 sq mi
Gauge elevation
4,884 ft
Subbasin (HUC-8)
10190005
Coordinates
40.13878, -105.02022
USGS site number
06730500
Records begin
1927-04-01 (99 years)
Rivermatics forecast
14-day flow outlook

14-day flow forecast

Based on observations through for Boulder Creek at Mouth near Longmont, CO. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.

Forecast daily mean discharge in cubic feet per second, by date
Date Low p10 Expected p50 High p90 Range
0.6 0.8 1
0.4 0.7 1.1
0.3 0.7 1.2
0.3 0.7 1.8
0.3 0.7 2
0.3 1 3.8
0.3 1.2 5.2
0.3 1.1 4.3
0.3 1 3.5
0.2 0.9 3.2
0.2 0.9 3.2
0.1 0.8 2.9
0.1 0.7 2.8
0.1 0.7 2.8

All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.

Typical flow by month

Long-term daily discharge percentiles from the USGS record (up to 99 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.

Historical monthly discharge percentiles in cubic feet per second
Month Low p10 Typical p50 High p90 Range
January 15.9 52.1 80.8
February 15.2 50.6 82.9
March 13.9 48 104.5
April 5.5 58.4 209.1
May 3.5 98.9 474
June 4 108.1 617.3
July 1.9 11.1 157
August 1.3 5.6 47.2
September 1.4 7.4 49.5
October 1.6 26.2 84.2
November 3.2 46.1 88.4
December 7.3 53.4 83.6

All values in cubic feet per second (cfs).

Common questions

When does Boulder Creek at Mouth near Longmont, CO normally run highest?
June, on the long-term record. The median daily flow that month is about 108.1 cfs, against 5.6 cfs in August, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
What is a normal flow for Boulder Creek at Mouth near Longmont, CO?
It depends on the month. In January, half of days historically fall near 52.1 cfs, with the middle 80% of days between 15.9 and 80.8 cfs. The month-by-month table on this page gives the full range.
How long has Boulder Creek at Mouth near Longmont, CO been measured?
Discharge records at USGS site 06730500 begin in 1927, about 99 years, covering roughly 9,193 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
Is there a flow forecast for Boulder Creek at Mouth near Longmont, CO?
Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
Where is Boulder Creek at Mouth near Longmont, CO?
The gauge sits at 40.13878, -105.02022, in Colorado, in hydrologic subbasin 10190005, at an elevation of about 4,884 feet, draining roughly 447 square miles.
Can I use Boulder Creek at Mouth near Longmont, CO data for flood or safety decisions?
No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.

Upstream and downstream on the Boulder Creek

Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Boulder Creek in full.

Other gauges in this subbasin