Enhancing and Protecting Water Quality

brown trout in the water

The qual­i­ty of the water in our water­shed is vital to the 9 mil­lion New York State res­i­dents who depend on it for con­sump­tion, and to the peo­ple liv­ing in the water­shed who enjoy and depend on healthy streams. Water qual­i­ty ben­e­fits the local econ­o­my through rev­enues gen­er­at­ed by fish­ing, white­wa­ter, and oth­er stream-based recre­ation­al activ­i­ties. Water qual­i­ty is vital for the plants and ani­mals that share our water­shed, and is part of the nat­ur­al beau­ty of this place.

While over­all water qual­i­ty in the Ashokan Water­shed is good, the major water qual­i­ty con­cern affect­ing drink­ing water is tur­bid­i­ty. Sec­ondary water qual­i­ty issues are nutri­ent enrich­ment, inva­sive species, habi­tat alter­ation, and the poten­tial loss of cold water as a result of cli­mate change. There may be impacts from pol­lu­tants that orig­i­nate in stream­side areas, such as fuel oil tanks, sep­tic sys­tems, and runoff from roads.

Tur­bid­i­ty is the cloudi­ness or hazi­ness of water result­ing from sed­i­ment sus­pend­ed in the water col­umn. In the Ashokan water­shed, sus­pend­ed sed­i­ments are most­ly clay and silt par­ti­cles that enter the stream through erod­ing stream chan­nels and hill­slopes. Tur­bid­i­ty is what caus­es our watershed’s streams to run a red­dish-brown or “choco­late” col­or after heavy rain­storms. The clay par­ti­cles can har­bor virus­es and bac­te­ria mak­ing it more dif­fi­cult to effec­tive­ly treat the water for drink­ing use. If tur­bid­i­ty lev­els are ele­vat­ed for long peri­ods of time, it may adverse­ly affect local wildlife such as fish. Local­ized depo­si­tion of the silt par­ti­cles can clog the spaces between rocks in streambeds and reduce habi­tat for aquat­ic insects.

Stream Corridor Assessments

AWSMP address­es water qual­i­ty issues by per­form­ing stream cor­ri­dor assess­ment to diag­nose stream con­di­tions and iden­ti­fy ero­sion haz­ards and water qual­i­ty impair­ments. Stream assess­ments sup­port the devel­op­ment of stream man­age­ment plans and pro­vide the data nec­es­sary to com­plete stream restora­tion and sta­bi­liza­tion projects.

Geo­log­ic sources of tur­bid­i­ty exposed by erod­ing stream banks are mapped and cat­a­logued in com­put­er data­bas­es. This infor­ma­tion is used to under­stand the dis­tri­b­u­tion and nature of tur­bid­i­ty sources. The results of data analy­sis are used to pri­or­i­tize fur­ther assess­ment or rec­om­mend treat­ment options. AWSMP spon­sors research by the U.S. Geo­log­i­cal Sur­vey (USGS) to mon­i­tor tur­bid­i­ty and sus­pend­ed sed­i­ment load­ing in sev­er­al of the major streams of the water­shed. We are also work­ing with the NYS Geo­log­i­cal Sur­vey to map the glacial geol­o­gy of the watershed.

A major source of tur­bid­i­ty in today’s streams is the lega­cy of sed­i­ment left behind dur­ing the Ice Age. Sed­i­ment deposits are sub­se­quent­ly dis­turbed by erod­ing and unsta­ble stream chan­nels and hill­slopes. While ero­sion and depo­si­tion are nat­ur­al process­es oper­at­ing over large timescales, human devel­op­ment with­in stream cor­ri­dors can exac­er­bate ero­sion and intro­duce con­t­a­m­i­nants to the sys­tem. The appli­ca­tion of best man­age­ment prac­tices in set­tled areas can help to mit­i­gate these effects.

Restoration and Stabilization Projects

After sites with chron­ic sources of tur­bid­i­ty are iden­ti­fied through assess­ments, dif­fer­ent lev­els of man­age­ment inter­ven­tion are eval­u­at­ed. The options for stream man­age­ment range from doing noth­ing (where insta­bil­i­ty is caus­ing no prob­lems), to allow­ing nat­ur­al process­es to resolve the prob­lem, to assist­ed self-recov­ery and full restora­tion. In some reach­es, minor lev­els of man­age­ment inter­ven­tion can resolve an issue, such as ripar­i­an plant­i­ngs, slight bank grad­ing, or the con­struc­tion of iso­lat­ed struc­tures. Where full restora­tion of steam func­tion and capac­i­ty is required, man­age­ment may include exten­sive reshap­ing of the channel’s form. Engi­neer­ing sur­vey, design and con­struc­tion work are required for this lev­el of intervention.

Restora­tion and sta­bi­liza­tion projects are designed to reduce the long-term, chron­ic intro­duc­tion of fine sed­i­ment sources to the stream. AWSMP pro­vides pro­fes­sion­al ser­vices and fund­ing for the design and imple­men­ta­tion of these projects, work­ing in coop­er­a­tion with landown­ers and munic­i­pal­i­ties. For more infor­ma­tion on com­plet­ed and ongo­ing restora­tion and sta­bi­liza­tion projects, see the Projects & Fund­ing section.