River Boyne Water Quality Management Plan - EPA

River Boynr Wnar Qunlily Managemrnr PlanBoyne clmnnel from Yellow River to Trim; downstream of the Yellow River. D.O. levels inthe Boyne chan17el appear to be relatively satisfactoiyRiver Boyne between Trim and Navan; this section of river was surveyed in the surrtmer of1989 at low flow. Variations from 65% - 144% satzrration D.?. were recorded atNewtownbridge; 48% - 158% saturation upstrearn of the conflue17ce with the KnightsbrookRiver and 62% 7 144% satzrration at Bective bridge. More recently in November, 1993, avalue of 16.1 nig/l showed significant supersaturation at Bective. ~Macrophyte and algalgrowth is extensive in these areas, particzrlarly between the ozrflall from Trim wastewater[reurnlent worh andBective bridge. Under critical low flow conditions in summer time, thissection of river wrrs shown to be marginal for compliance, with a risk of unsatisfactoryconditions. This requires litnitation of nutrient input and organic load to this section. In thedownstream section approaching Navan, dissolved oxygen levels were sotisfactoiy, exceeding60% saturation at all stages. Any nutrient load arising in the riverSkane does not appear tobe influencir~g conditions in the River BoyneRiver Boyne downstream of Navnn; D.O. levels nieaszrred downstreant of Navan showedvalues of 44% saturation at Broadboyne bridge on the 22nd Jirly, 1989 and 54% saturatiori011 the 18th July, at the same site, both recorded in the early niorning. Therefore, this area. . 4:was shown to be marginal for contpliance under cr~tc$al conditions. Extensive surveys;iroived that dissoh~ed oxygen levels less than 61nq/I $$were present in the stretch of rivertetweni Nwan town cnd Bmadboytze Bridge (~p$iiiiately 6.4kt1t) for o sign@cn~it periodof tinie. More recent data indi;ates a nior~y< ernte range from 7.1-i5.8 mg/l 02, The&cr of Nuvac weir would tend to bri@.&.O. levels dowristrean7 of the weir towardssaturrrtion level, providing snfe D.O. l&?)orfis~t in this area. Downsh.eum to Droghedo,&b S'D. 0. levels in the river oppear to be@~$ralIy satisfactory\ :&'o BlccAwater (Longwoo(/) River; w t surveys in May, 1989 recorded o D.0. ojc5.4~ag/l 02 hithe viciriiry of Blockwater ~i-&e and Johnstown Bridge zrrider eorly nior~ting conditions.This showls this river to be&;arginal for compliance with salmonid standards. Recent datashows a generally sotisjactoiy range of valuesFor inspection purposes only.Consent of copyright owner required for any other use.Kitinegad River; a niini~num D.O. value of 4.lntgfl02 was recorded in this river downstreamof Kinriegad in 1989. Associated growths of macrophytes and algae were noted in the areaconsistent with this low result. Recent critical values recorded were 4.4 mg/l in August, 1990,5.4 mgfl in August, 1991 and 3.9 mg/l in May 1995Atlrboy River, sinrilar results were recorded on the Athboy River in the region ofAthboy witha minimum value of 4.0nig/l02 in an area of extensive niacrophyte and algal growth. Recenrdata showed a range from 7 - I4 rng/l.Skane River; a minimuni value of 4.5nig/l 02 was recorded irr rhe ajernoon of 29th May,I990 017 this river, indicating depressed dissolved oxygen values, associated with organicloading. Recent data shows occasio~ialow values at Drumree (6.0, 5.9, 4.7, 4.2, 5.1 mg/l).These levels are irnsatisfactoiyEPA Export 26-07-2013:17:27:01