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Home My WebLink AboutVer _COMPLETE FILE_19961031 State of North Carolina Department of Environment, Health and Natural Resources Division of Water Quality Ja mes B. Hunt, Jr., G ove mor Jonathan B. Howes, Secretary A. Preston Howard, Jr., P.E., Director November 4,1996 Alice L. Anderson NCDEHNR Coastal Mosquito Mgmt. 5447 Highway 70 West 205 Country-Aire Suites Morehead City, NC 28557 Re: Conway Stream Channelization Project Dear Ms. Anderson: On October 10, 1996 Jean Manuele with the US Army Corps of Engineers (USACOE) Raleigh Field Office, Kevin Moody with the US Fish and Wildlife Service, and myself met with you and Bob Bridges with the Town of Conway to discuss further channelization of a small stream on the southwest side of Conway. At that meeting you requested that written comments be forwarded to you and that you would review them with Town officials. During our site visit we looked at the channelized portion of the stream which begins behind residences along US 158 and at the lower end of the channelization on the west side of NC 35 south of Conway. Mr. Bridges indicated that the approximately 1 mile long channelization project was done about 15 years ago and drains about 1500 acres. He also indicated that there had been some flooding of the stream from the record breaking rainfall associated with Hurricane Bertha and Hurricane Fran. Mr. Bridges expressed the Town's desire to do further excavation in the existing stream channel and to extend the channelization another 1000 feet south. The major concern seemed to be the flooding that occurred after heavy rains. Neither you or Mr. Bridges indicated that there was a real mosquito problem. The water of Doolittle Millpond to which this stream flows carnes a classification of B NSW which identifies it as protected for primary recreation as well as fishing, aquatic life, and wildlife uses, and as nutrient sensitive waters of the Chowan River Basin. At the upper end, the channelized stream flows through a residential section of Conway and is about 6 feet lower than the surrounding grade with banks up to 15 feet wide at the top. A wide spoil benn separates the stream from its floodplain of bottomland hardwoods. Side ditches with culverts under the berm have been cut through the floodplain forest. There was little evidence that the stream overflows the channelized banks at this point. At the lower end of the channelization, the shallow stream is up to 10 feet in width with wider banks and a lower benn on the west side of the stream. Here the stream does show signs of occasional overflow back into the floodplain forest. The land use adjacent to the floodplain through this section is farm fields. At the end of the channelization project, the stream spreads out more into the wetland floodplain forest which is dominated by mature hardwood species including tulip poplar, black gum, and swamp chestnut oak. Using the Division's wetland evaluation method, this floodplain forest has rating of 78% with significant functions in water storage, bank stabilization, and pollutant removal. Environmental Sciences Branch . 4401 Reedy Creek Road Telephone 919-733-9960 An Equal Opportunity Affirmative Action Employer Raleigh, North Carolina 27607 FAX # 733-9959 50% recycledllO% post consumer paper Unfortunately for the Town's proposal, the Division now discourages the channelization of streams and seeks to preserve or restore floodplain wetlands similar to those along this stream. The value of these wetland systems to store water, remove pollutants, and protect water quality downstream has been clearly documented. Any extension of the channelization project would clearly impact the bottomland hardwood forest through drainage and the spoil material and would seriously degrade the existing functions protecting water quality. Further channelization would not be allowed under current water quality rules. As for the deepening or widening of the existing channelized stream, the Division may allow some limited removal of sediments to improve drainage through the residential areas although I don't see where it is particularly needed. The largest constriction to storm water flow along the channel is the farm road crossing south of Town. With only one culvert, this crossing slows water flow through the floodplain and would back water up during extremely heavy rainfall events. The placement of more culverts or a bridge a this crossing would do more to improve flow than deepening the channel. It also appears that much of sediment in the channel and in the wetland forest is soil that has washed in from the surrounding farm fields. Improved erosion control practices on the adjacent farmlands might reduce the amount of sedimentation in the stream. In summary, the Division feels that the flooding that occurred this summer and fall was due to record breaking rainfalls and not to drainage problems along the stream. Further excavation or channelization of the stream that would further impact the adjacent wetlands or downstream water quality would not be allowed. The Division would support improvements in the road crossing discussed earlier and may allow limited excavation in the residential section if the need can be clearly shown. If you have any questions concerning this matter please feel free to contact me at (919) 733-1786. Sincerely, ,;1 - /Jc Itt~~ Peter B. Colwell Environmental Specialist cc: John Dorney, DWQ Central Office Jean Manuele, USACOE Raleigh Field Office Kevin Moody, Us Fish And Wildlife Service Danny Smith, DWQ Raleigh Regional Office Project Name COvtlA/a V County !Jell" {IA W,tM",..l:PI/! / Wetland Area 10+ Name of evaluator #,{; ~/lA/'.e (I Nearest Road tlJc, 33- acres Wetland Width 300 feet Date /0/7// '16 Wetland Location _;m pond or lake ~ on perennial stream on intermittent stream within interstream divide other Soil series _ predominantly organic - humus, muck, or peat _ predominantly mineral - non-sandy _ predominantly sandy Hydraulic factors _ steep topography _ slitched or channelized .ktotal wetland width ~ 1 00 feet Adj acent land use (within 1/2 mile upstream, upslope, or radius) _ forested/natural vegetation - % _ agriculture, urban/suburban:lQ.. % _ impervious surface 2- % Dominant vegetation (1) fer! lAo/l~ (2) J It C:UWl (3) 5wo. WI' C /;verl'1. f.{ f 04 ~ _ semipermanently to permanently jlooded or inundated ~ seasonally flooded or inundated _ intermittanly flooded or temporary surface water no evidence of flooding or surface water '1 '-I S :5 1If3 J Flooding and wetness Wetland ty;>e (select one)* . ~Bottom1and hardwood forest Pine savanna Headwater forest Freshwater marsh _ Swamp forest _ Bog/fen Wet flat _ Ephemeral wetland Pocosin _ Carolina Bay _ Bog forest Other , ____~______*_t~~!~!~~g_~~!.~J!l_9~<2!E.~~.P.E~~~t!2_~~~!J~~'!~~~1.!/PE~~~~.9!_~!!-~~~~~~!~------------------------- weight x 4.00 = x 4.00 = * x 5.00 = ' x 2.00 = x 4.00 = x 1. 00 = R A T I N G Water storage Bank/Shoreline stabilization Pollutant removal Wildlife habitat Aquatic life value RecreationlEducation 1'..,....'.........1 ~~~~i~~~~.~~~~~~~~~~ !\\\HI~.~IM I..."..'.......'..j m~~~~III~~l~~~~[ Wetland Rating :\Ij~~~j~~jjtjj~~~:j:~~~~~~j~~~~~~~\~j~j~~j::~~~j\j:j!t ...~~..... . ........... ,,--_.... ............ j~ij:~j~\: :~:~:j:~:tj:::lli: :;:i=::.t:;:;=;:::: :::::::::::::::::::::::: W * Add 1 point if in sensitive watershed and > 1 0% nonpoint disturbance within 1/2 mile upstream, __________~J2~L~~~~~!~~iy~------------------------------------------------------------------------------------------