Several of the existing bridges were constructed of wood, and had multiple openings, which restricted the flow of water through them. They were reconstructed in a variety of styles. Horkstow Bridge was planned as a cast iron bridge with an span, but was built as a suspension bridge with a span of . It is one of the earliest suspension bridges still standing, and the only suspension bridge known to have been designed by Rennie. The bridge at Yarborough Mills, in Brigg, has a single segmental arch build of stone, and was opened in 1827, although it has been widened subsequently. The bridge at Brandy Wharf, which was completed in the following year, is more typical of the structures built at that time, consisting of an iron span with stone abutments. Harlam Hill lock was reconstructed in 1827, but plans for a second lock at Kingerby were dropped. Discussions had taken place in 1823 about extending the navigation to Market Rasen. The plans were revised and expanded in 1829, by which time a link from Bishopbridge to Barlings Eau and the River Witham was suggested. It would have cost £90,000 to build the waterway, including the construction of seven locks. Although the scheme was dropped, Rennie was still championing it in 1841 and 1844.
seveRAL Of tHe ExiSTiNg brIDges were cOnStrucTeD Of WoOd, and HAd MultiPle opeNiNgs, wHicH restRicTed the flow of Water throUGh them. they weRE recoNSTrUcteD in a vArIety Of styles. horKsTOw BrIDge was PlaNNeD As a CasT iroN bRidge with An span, buT wAs BuILT As a SusPENsIon brIdge wIth a sPaN oF . iT IS onE oF the earliEst Suspension bridgeS sTilL STAnDIng and tHe onLy suspensioN bridge KnOWn TO have beEn designed bY renniE. THe bRiDge at yarBOrOugh mIllS, iN BrigG, Has a SinGle segmental Arch build Of stone, aNd wAs oPENED in 1827, aLtHOUgh it Has BEEn wIdEneD SubseqUentLy. tHE brIdGE at brAndY whARf, whIch Was coMPLeTed iN The fOllowing yEar, IS morE tYpIcal of the strUcturEs buIlT at tHAt tIme, coNsisting of an iron span witH Stone aBuTmentS. hArLAM Hill lOCk was rEcOnstRuCTed in 1827, BuT plans fOr a SecOnd LOck aT kiNgErby were dRoppED. DisCUsSions hAD tAkEn PlAcE in 1823 aBout exTending The navigation To mArkeT rAsen. thE pLanS weRe RevisED And expAndeD in 1829, By wHiCh time a liNK from bishopbridgE tO BArlInGs eAu aND tHe rIveR witham Was suGgeSted. it Would hAve coST £90,000 tO Build thE WAterwAY, iNcludINg THe construCtiOn of sevEn lOcKS. altHougH tHe schEmE was droPPed, rennIe wAs sTIll CHAmPIoniNg it in 1841 anD 1844.