U ovom smo radu istraživali vezu između broja svojti unutar triju redova vodenih kukaca: vodencvjetova (Ephemeroptera), obalčara (Plecoptera) i tulara (Trichoptera), ukupnog broja svojti (EPT), kao i udjela EPT jedinki u zajednici bentoskih makrobeskralješnjaka (EPT[%]) te metala otopljenih u vodi i fizikalno-kemijskih pokazatelja. Prisustvo EPT zajednice s velikim brojem svojti i velikim udjelom u ukupnoj zajednici bentoskih makrobeskralješnjaka se obično povezuje s dobrom kvalitetom slatkovodnih ekosustava. Svi podaci su prikupljeni u sklopu programa sustavnog praćenja stanja površinskih voda tijekom 8 godina (2010.-2017.). Ukupno je analizirano 247 uzoraka bentoskih makrobeskralješnjaka na 172 postaje uzorkovanja, a svi uzorci prikupljeni su koristeći AQEM metodu uzorkovanja. Voda za određivanje koncentracije otopljenih metala i osnovnih fizikalno-kemijskih pokazatelja uzorkovana je u godini kad je prikupljen uzorak bentoskih makrobeskralješnjaka, a svi navedeni pokazatelji mjereni su standardnim analitičkim metodama za analizu kakvoće površinskih voda (ISO norme). Pronađena je negativna veza EPT zajednice (broj svojti vodencvjetova (E), obalčara (P), tulara (T) i ukupno (EPT), te udio jedinki EPT u ukupnom uzorku (EPT [%])  s fizikalno-kemijskim pokazateljima, kao što su to npr.:  temperatura i P = -0,528, električna vodljivost i P = -0,491,  ukupna tvrdoća i EPT = -0,493) te slaba negativna veza s alkalitetom i ukupnom suspendiranom tvari. Spearmanov koeficijent korelacije ukazuje i na statistički značajnu negativnu povezanost između  i koncentracije mangana s P i T (-0,540, -0,380 slijedom) te arsena s EPT[%] (-0,421). S ostalim metalima (bakar, cink, kadmij, krom, nikal, olovo, živa i željezo) korelacije su slabe do beznačajne. Rezultati ovog istraživanja ukazuju da bi uporaba EPT kao bioindikatora mogla biti važna strategija pri određivanju zagađenja manganom i arsenom u vodenom okolišu.. The paper investigates the relationship between the number of taxa within three orders of aquatic insects -  Ephemeroptera (mayflies), Plecoptera (stoneflies) and Trichoptera (caddisflies), the total taxa (EPT) and EPT individuals in thebenthic macroinvertebrate community (EPT[%]), including dissolved metals in the water and physico-chemical parameters. The presence of EPT community with numerous taxa and a large share in the totalmacroinvertebrate community is usually associated with good water quality of freshwater ecosystems. All collected data used in this study originate from the national monitoring programme of surface water quality within a period of 8 years (2010 - 2017). In total, 247 samples of benthic macroinvertebrates from 172 sampling stations were analysed. All samples were collected according to the AQEM sampling protocol. The water used for determining the concentrations of dissolved metals and basic physico-chemical parameters was sampled in the same year when the samples of macrozoobenthos were collected, and all mentioned parameters were measured according to standard analytical methods for analysing surface water quality (ISO standards). The statistical analysis showed a significant negative correlation of the EPT assemblage (number of taxa of Ephemeroptera (E), Plecoptera (P), Trichoptera (T) and altogether (EPT), as well as the share of EPT individuals in the sample (EPT [%]) with physico-chemical parameters, such as temperature and (P) = -0.528, electric conductivity and (P) = -0.485, total hardness and EPT = -0.493, including a weak negative correlation with alkalinity and total suspended solids. The Spearman's coefficient of the correlation indicated a statistically significant negative correlation of Manganese with P and T (-0.540 and -0.380, respectively) and of Arsenic with EPT[%] (-0.421). The correlations with other metals (Copper, Zinc, Cadmium, Chrome, Nickel, Lead, Mercury and Iron) were weak to insignificant. The results of the present study suggest that the use of EPT as bioindicators may be an important strategy for detecting Manganese and Arsenic pollution in aquatic environments.