caused by the inclusion of large non-contributing districts in the measured drainage area, by lack of information concerning water diverted for any use, or by inability to interpret the effect of artifical regulation of the flow of the river above the station. "Second-feet per square mile" and "run-off (depth in inches)" are therefore not computed if such errors appear probable.

The table of monthly discharge gives only a general idea of the flow at the station and should not be used for other than preliminary estimates; the tables of daily discharge allow more detailed studies of the variation in flow. It should be borne in mind, however, that the observations in each succeeding year may be expected to throw new light on data previously published.

GAGING STATION RECORDS

HUDSON RIVER BASIN

HUDSON RIVER NEAR INDIAN LAKE

Location. About 1 mile below the mouth of Cedar river, 11⁄2 miles above the mouth of Indian river and 6 miles northeast of Indian Lake village, Hamilton county.

Drainage area.-418 square miles (measured on U. S. G. S. topographic maps).

Records available.-August 30, 1916, to September 30, 1917.

Gage.- Gurley printing water stage recorder on right bank. Inspected by John A. Bolton.

Discharge measurements. Made from cable about 100 yards below gage, or by wading.

Channel and control. Solid ledge overlain with coarse gravel; probably permanent.

Extremes of discharge.- Maximum stage during year from water stage recorder, 9.87 feet at 11 A. M. June 12 (discharge, 13,500 second-feet); minimum stage from water stage recorder, 1.62 feet from 10 A. M. to 10 P. M. October 13 (discharge, 109 second-feet).

Ice. Stage-discharge relation probably somewhat affected by ice. Regulation. Large diurnal fluctuation due to logging operations during the spring months. Seasonal distribution of flow slightly affected by storage. Accuracy. Stage-discharge relation practically permanent; affected by ice from December to March and by logs during the latter part of June. Rating curve fairly well defined between 75 and 600 second-feet and well defined between 600 and 6,000 second-feet. Operation of water stage recorder satisfactory. Daily discharge ascertained by applying mean daily gage height to rating table except when fluctuation required mean of hourly discharge. Results good.

Cooperation.-Station established and maintained by the United States Geological Survey in cooperation with the Conservation Commission.

Discharge measurements of Hudson River near Indian Lake, during the year ending September 30, 1917

Daily discharge in second-feet, of Hudson river near Indian Lake, for the year ending September 30, 1917

NOTE.- Discharge October 10, 20, 21, November 11, 14, 21, 22, 27, 30, April 19 to June 12, and September 21 is mean of twenty-four hourly discharge values. Discharge December 14 to April 2 determined, because of ice, from discharge measurements, weather records and study of gage height graph. Discharge June 13 to September 30 determined from special log jam rating because of log jam on control.

Monthly discharge of Hudson River near Indian Lake, for the year ending September 30, 1917 [Drainage area, 418 square miles]

Location. At the two-span steel highway bridge in the village of North Creek, Warren county, immediately above the mouth of North creek.

Drainage area.- 804 square miles.

Records available.- September 21, 1907, to September 30, 1917.

Gage.- Chain, at upstream side of left span of the bridge; datum unchanged; read by William Alexander.

Discharge measurements.— Made from the upstream side of the highway bridge.

Channel and control.- Heavy gravel; fairly permanent.

Extremes of discharge.- Maximum stage recorded during year, 10.6 feet at noon June 12 (discharge about 21,000 second-feet); minimum stage recorded 2.35 feet at 4:30 P. M., November 21 (discharge 360 second-feet).

1907-1917: Maximum stage recorded 12.0 feet during the evening of March 27, 1913 (discharge about 30,000 second-feet); minimum stage, 2.05 feet at 7:05 A. M., September 30, 1913 (discharge 168 second-feet). Ice.- Stage-discharge relation affected by ice.

Regulation. The numerous lakes and ponds in the basin of the upper Hudson have a decided effect on the low water flow especially the reservoir at Indian Lake. Many of the reservoirs are used to make flood waves in the spring in connection with log driving.

Accuracy.-Stage-discharge relation practically permanent; affected by ice from December to March, inclusive. Rating curve well defined between 250 and 6,000 second-feet. Gage read to half tenths twice daily. Daily discharge ascertained by applying mean daily gage heights to rating table. Results good during open water period; fairly good during period when stage-discharge relation is affected by ice.

Cooperation.-Station established and maintained by the United States Geological Survey in cooperation with the Conservation Commission.

Discharge measurements of Hudson River at North Creek during the year ending September

Daily discharge, in second-feet, of Hudson River at North Creek, for the year ending September

NOTE.- Discharge, December 16 to March 27, estimated because of ice, from discharge measurements, weather records and study of gage height graph.

Monthly discharge of Hudson River at North Creek, for the year ending September 30, 1917 [Drainage area, 804 square miles]

Location. At the Delaware and Hudson railroad bridge near the Thurman railroad station, Warren county about one-half mile below the mouth of Schroon river and about 13 miles above the month of Sacandaga river. Drainage area.-- 1,550 square miles.

Records available.— September 1, 1907, to September 30, 1917.

Gage.— Chain, at upstream side near center of left span; datum unchanged; read by S. H. Spencer.

Discharge measurements.— Made from upstream side of bridge.

Channel and control.- Sand and gravel; fairly permanent. Logs occasionally lodge on a small island on the control.

Extremes of discharge.— Maximum stage recorded during year, 9.45 feet at about 4 P. M., June 12 (discharge 24,800 second-feet); minimum stage recorded, 2.08 feet at about 7 A. M., November 22 (discharge about 480 secondfeet).

1907-1917: Maximum stage, 12.5 feet during the late evening of March 27, 1913, determined by leveling from flood marks (discharge about 46,000 second-feet); minimum stage recorded, 2.12 feet at 8:55 A. M. and 6:20 P. M., September 30, 1913 (discharge about 290 second-feet).

Ice.- Stage-discharge relation seriously affected by ice. Discharge determined from records at North Creek and Riverbank.

Regulation. Discharge is regulated to some extent by the storage reservoirs at Indian Lake and Schroon Lake and the mills on the Schroon river. Accuracy. Stage-discharge relation practically permanent; affected by ice during large part of the period from December to March, inclusive. Rating curve well defined between 550 and 20,000 second-feet. Gage read to hundredths twice daily. Daily discharge ascertained by applying mean daily gage height to rating table. Results good. Estimated results during frozen period fair.