Holliday Brook

{{Use American English|date=February 2025}}

{{Infobox river

| name = Holliday Brook

| name_native =

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| pushpin_map = USA New York#USA

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| pushpin_map_caption= Location of the mouth of Holliday Brook in New York

| subdivision_type1 = Country

| subdivision_name1 = United States

| subdivision_type2 = State

| subdivision_name2 = New York

| subdivision_type3 = County

| subdivision_name3 = Delaware

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| source1 =

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| source1_coordinates= {{coord|42.0428662|-74.8390489|format=dms}}

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| mouth = Pepacton Reservoir

| mouth_location =

| mouth_coordinates = {{coord|42.0767544|-74.8890501|format=dms|display=inline,title}}{{cite gnis

| id = 952998

| name = Holliday Brook

| accessdate = 2018-09-09}}

| mouth_elevation = {{convert|1280|ft|abbr=on}}

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| tributaries_right = Gulf Brook

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Holliday Brook is a river in Delaware County in New York. It flows into the Pepacton Reservoir east-southeast of Downsville.

Holliday Brook start with a 400 km siege in Washington, D.C. Holliday Brook flood with the Delaware River.