The 7-day, 10-year flow (7Q10) is the most commonly used statistical low-flow index in Rhode Island for water-resources planning and management. Flow-duration values are also important indicators of low flows. Methods for estimating the 7Q10flow and flowduration values of streams in Rhode Island at partial-record sites and ungaged sites are based on the knowledge that low flows are sustained almost entirely by the discharge of water from adjacent aquifers.Discharge was determined at 25 low-flow partial-record sites. Relations were developed between base-flow discharges at the partial-record sites and daily mean discharges at eight continuous-record stations. The 7Q10 and flow-duration values at each partialrecord site were established by transferring the 7Q10flow and the selected flow-duration values from the selected continuous-record station through the regression line.A regression equation was developed relating the percentage of underlying stratified drift and till in the contributing drainage area to the 7Q10flow at 21 long-term continuousrecord sites in and around Rhode Island. Coarse-grained stratified drift yields significantly more water to streams during low flow than does till. The regression equation is 7Q10 flow = 0.67 (area of stratified drift) + 0.03 (area of till). The standard error of estimate is 2.6 cubic feet per second, which is equivalent to 40 percent of the mean value, and the correlation coefficient is 0.97.

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